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WO2026020161A1 - Activatable il-12 constructs and related compositions and methods - Google Patents

Activatable il-12 constructs and related compositions and methods

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Publication number
WO2026020161A1
WO2026020161A1 PCT/US2025/038373 US2025038373W WO2026020161A1 WO 2026020161 A1 WO2026020161 A1 WO 2026020161A1 US 2025038373 W US2025038373 W US 2025038373W WO 2026020161 A1 WO2026020161 A1 WO 2026020161A1
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WIPO (PCT)
Prior art keywords
amino acids
activatable
polypeptide
fusion protein
construct
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/US2025/038373
Other languages
French (fr)
Inventor
Na CAI
Erwan LE SCOLAN
Nicole G. LAPUYADE
Michael B. Winter
Olga Vasiljeva
Madan M. Paidhungat
Dylan L. Daniel
Bruce HOWNG
Trang T. T. VU
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cytomx Therapeutics Inc
Original Assignee
Cytomx Therapeutics Inc
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Filing date
Publication date
Application filed by Cytomx Therapeutics Inc filed Critical Cytomx Therapeutics Inc
Publication of WO2026020161A1 publication Critical patent/WO2026020161A1/en
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
    • C07K14/52—Cytokines; Lymphokines; Interferons
    • C07K14/54—Interleukins [IL]
    • C07K14/5434—IL-12
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K45/00—Medicinal preparations containing active ingredients not provided for in groups A61K31/00 - A61K41/00
    • A61K45/06—Mixtures of active ingredients without chemical characterisation, e.g. antiphlogistics and cardiaca
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
    • C07K14/52—Cytokines; Lymphokines; Interferons
    • C07K14/54—Interleukins [IL]
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
    • C07K14/52—Cytokines; Lymphokines; Interferons
    • C07K14/54—Interleukins [IL]
    • C07K14/5428—IL-10
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
    • C12N15/09—Recombinant DNA-technology
    • C12N15/11—DNA or RNA fragments; Modified forms thereof; Non-coding nucleic acids having a biological activity
    • C12N15/62—DNA sequences coding for fusion proteins
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K38/00—Medicinal preparations containing peptides
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/30—Non-immunoglobulin-derived peptide or protein having an immunoglobulin constant or Fc region, or a fragment thereof, attached thereto
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/50—Fusion polypeptide containing protease site
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/70—Fusion polypeptide containing domain for protein-protein interaction
    • C07K2319/74—Fusion polypeptide containing domain for protein-protein interaction containing a fusion for binding to a cell surface receptor
    • C07K2319/75—Fusion polypeptide containing domain for protein-protein interaction containing a fusion for binding to a cell surface receptor containing a fusion for activation of a cell surface receptor, e.g. thrombopoeitin, NPY and other peptide hormones

Definitions

  • IL12 is a heterodimeric molecule composed of an alpha chain (the p35 subunit) and a beta chain (the p40 subunit) covalently linked by a disulfide bridge to form the biologically active 70 kDa dimer.
  • IL12 elicits strong antitumor effects by stimulating unmodified immune cells, including T cells and natural killer (NK) cells.
  • NK natural killer
  • IL12 strongly induces IFN- ⁇ from unmodified NK cells and activated T cells.
  • IL12 therapy in humans is often accompanied by undesired side effects including toxicity,flu-like symptoms, nausea, vomiting, diarrhea, low blood pressure, arrhythmia, and death.
  • no IL12-based therapeutic products have been approved for clinical application.
  • the present disclosure provides activatable interleukin 12 (IL12) fusion proteins and activatable IL12 constructs (“AICs”) that include one or more novel structural formats and/or masking moieties.
  • IL12 activatable interleukin 12
  • AICs activatable IL12 constructs
  • the present disclosure provides activatable interleukin 12 (IL12) fusion proteins comprising one or more polypeptide chains.
  • AICs activatable IL12 constructs
  • N' is an amino terminus of the activatable IL12 fusion protein
  • C' is a carboxy terminus of the activatable IL12 fusion protein.
  • At least one of L1 and L2 comprises a cleavable moiety (CM).
  • L2 comprises a CM.
  • L1 comprises a CM.
  • L1 does not contain a CM.
  • the activatable IL12 fusion protein can have 1.5-fold to about 1000-fold, or about 2-fold to about 100-fold, or about 100-fold to about 1000-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM-MM- DD1-N' or N'-p40-p35-CM-MM-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-MM-CM1-p40-p35-CM2-DD1-N' or N'-MM-CM1-p40-p35-CM2- DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-CM1-DD1- N' or N'-p40-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM- 2 CYTX-115-PCT 4862-0152WO1 CM2-p35-CM3-DD2-N' or N'-MM-CM2-p35-CM3-DD2-C'.
  • the activatable IL12 construct can have about 50-fold to about 1000-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay.
  • the disclosures are intended to include the subunits arranged in either order from N-terminus to C-terminus.
  • any of the polypeptides according to the present disclosures are intended to include a structural arrangement comprising N'-p40-p35-C' as well as a structural arrangement comprising N'-p35-p40-C'.
  • DD1 is more proximal to the p35 domain than to the p40 domain.
  • the activatable IL12 construct can have about 10- fold to about 50-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay.
  • the present disclosure provides an activatable IL12 fusion protein comprising a first polypeptide chain comprising from N-terminus to C-terminus: MM-LR1-IL12 ⁇ -IL12′′-LR2- EM; or IL12 ⁇ -IL12′′-LR1-MM-LR2-EM.
  • the present disclosure provides an activatable IL12 fusion protein or an activatable IL12 construct comprising: a first IL12 subunit and a second IL12 subunit; a first linking region (LR1) and a second linking region (LR2); a half life extension moiety (EM), and a masking moiety (MM); wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM), wherein the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the MM by the LR1 and the MM is coupled to the EM by the LR2, or wherein the first IL12 subunit is coupled to the MM by the LR1, the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the EM by the LR2.
  • CM cleavable moiety
  • the present disclosure provides an activatable IL12 construct comprising a dimer of: i) a first polypeptide comprising a) and a second polypeptide comprising a); ii) a first polypeptide comprising b) and a second polypeptide comprising b); iii) a first polypeptide comprising c) and a second polypeptide comprising c); iv) a first polypeptide comprising d) and a second polypeptide comprising d); v) a first polypeptide comprising a) and a second polypeptide comprising b); vi) a first polypeptide comprising a) and a second polypeptide comprising c); vii) a first polypeptide comprising a) and a second polypeptide comprising d); viii) a first polypeptide comprising b) and a second polypeptide comprising c); ix) a first polypeptide comprising b) and a second polypeptide compris
  • the present disclosure provides a (recombinant) cell carrying the nucleic acid encoding the activatable IL12 fusion protein or the activatable IL12 construct of any one or combination of aspects disclosed herein.
  • the cell is a prokaryotic cell.
  • the cell is a eukaryotic cell.
  • the eukaryotic cell is a mammalian cell.
  • the present disclosure provides a method of producing the activatable IL12 fusion protein or the activatable IL12 construct of any one or combination of aspects disclosed herein comprising: a) culturing a cell of any one or combination of aspects disclosed here in a liquid culture medium to produce the activatable IL12 fusion protein or the activatable 6 CYTX-115-PCT 4862-0152WO1 IL12 construct; and b) recovering the activatable IL12 fusion protein or the activatable IL12 construct from the cell or the liquid culture medium.
  • FIG.1A is a schematic of ProC2020.
  • FIG. 1B is a schematic of ProC1910–1915. The key shown to the right of FIGs 1A-1B applies to all of FIGs.1A-1H.
  • FIG. 1C shows a schematic of ProC1726
  • FIG. 1D shows a schematic of ProC1977–ProC1982 and ProC2695–ProC2705 and ProC1725
  • FIG. 1E shows a schematic of ProC1727
  • FIG. 1F shows a schematic of ProC670
  • FIG. 1G shows a schematic of ProC671, and FIG.
  • FIG. 1H shows a schematic of an AIC comprising p40-p35-CM-MM-CM-DD, wherein the DD is dimerized with a second polypeptide that is a DD.
  • FIG. 1I shows a schematic of an AIC with two polypeptide chains comprising p40-p35-CM-MM-CM-DD, wherein the DDs are dimerized.
  • FIG. 1J shows a schematic of an AIC comprising p40-p35-CM-MM-CM-DD, wherein the MM is a split MM with an internal linker comprising a CM within the MM sequence according to the structure: MM’-CM- MM”, and wherein the DD is dimerized with a second polypeptide that is a DD.
  • FIG. 1H shows a schematic of an AIC comprising p40-p35-CM-MM-CM-DD, wherein the DD is dimerized with a second polypeptide that is a DD.
  • FIG. 1K shows a schematic of an AIC with a first polypeptide chain comprising p40-p35-CM-MM-CM-DD, wherein the MM is a split MM with an internal linker comprising a CM within the MM sequence according to the structure: MM’-CM-MM”, and a second polypeptide chain with a second MM and a CM comprising the structure MM-CM-DD, and wherein the DDs are dimerized.
  • the MM in the first polypeptide construct in Fig. 1K is not a split mask. Examples of this alternative construct are in AICs ProC5805 through ProC5808. [0026] FIG.
  • FIG. 2 shows a polyacrylamide gel electrophoresis (PAGE) image of the indicated constructs before and after treatment with MMP14.
  • FIG. 3 shows a PAGE image of the indicated constructs before and after treatment with MMP14.
  • FIG. 4 shows a PAGE image of the indicated constructs before and after treatment with MMP14.
  • FIG. 5 shows PAGE images of the indicated constructs before and after treatment with uPA.
  • FIG. 6 shows IL12 activity vs. concentration curves for the indicated AICs and rhIL12.
  • FIG. 7 shows IL12 activity vs.
  • FIG. 8 shows IL12 activity vs. concentration curves for the indicated AICs and rhIL12.
  • FIG. 9 shows IL12 activity vs. concentration curves for the indicated AICs and rhIL12.
  • FIG. 10 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes) and rhIL12.
  • FIG. 11 shows PAGE images of the indicated constructs before and after treatment with MMP9.
  • FIG. 12 shows PAGE images of the indicated constructs before and after treatment with MMP9. [0037] FIG.
  • FIG. 13 shows PAGE images of the indicated constructs before and after treatment with MMP2 and MMP9.
  • FIG. 14 shows PAGE images of the indicated constructs before and after treatment with MMP9.
  • FIG. 15 shows PAGE images of the indicated constructs before and after treatment with MMP2.
  • FIG. 16 shows PAGE images of the indicated constructs before and after treatment with MMP2.
  • FIG. 17 shows PAGE images of the indicated construct before and after treatment with MMP2.
  • FIG.18 shows IL12 activity vs. concentration curves for the indicated AIC both activated (cleaved) (open shapes) and uncleaved (dark shapes).
  • FIG. 19 shows IL12 activity vs.
  • FIG. 20 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes).
  • FIG. 21 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes).
  • FIG. 22 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes).
  • FIG. 23 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes).
  • FIG.24 shows IL12 activity vs. concentration curves for the indicated AIC both activated (cleaved) (open shapes) and uncleaved (dark shapes).
  • FIG. 25 shows anti-tumor activity for the indicated AICs in MC38 syngeneic tumor model.
  • FIG. 26 shows plasma cytokine levels on day 2 in MC38 tumor-bearing animals treated with IL12 AICs.
  • FIG. 25 shows anti-tumor activity for the indicated AICs in MC38 syngeneic tumor model.
  • FIG. 27 shows plasma cytokine levels on day 5 in MC38 tumor-bearing animals treated with IL12 AICs.
  • FIG. 28 shows plasma alanine transaminase (ALT) and alanine aminotransferase (AST) levels on day 12 in MC38 tumor-bearing animals treated with AICs.
  • FIG. 29 shows exemplary configurations of AICs and exemplary lengths of amino acids between the depicted elements.
  • FIG. 30 shows exemplary AICs: ProC1725, ProC1726, ProC1727, and ProC2020. [0055] FIG.
  • FIG. 31 shows exemplary AICs: ProC760, ProC1910 to ProC1915, ProC671, ProC1977 to ProC1982, and ProC2695 to ProC2705.
  • FIG.32 shows exemplary AICs: ProC5152, ProC5153, ProC5150, ProC5151, ProC5585, ProC5586, ProC5587, ProC5866, ProC5581, ProC5580, ProC5589, and ProC5588.
  • FIG. 33 shows exemplary AICs: ProC5333, ProC5334, ProC5745, ProC5867, ProC5746, ProC5868, ProC5747, ProC5874, ProC5581, and ProC5882.
  • Consisting and its derivatives, as used herein, are intended to be closed terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but exclude the presence of other unstated features, elements, components, groups, integers and/or steps.
  • Consisting essentially of is intended to specify the presence of the stated features, elements, components, groups, integers, and/or steps as well as those that do not materially affect the basic and novel characteristic(s) of features, elements, components, groups, integers, and/or steps.
  • Reference to any one of these transition terms i.e., “comprising,” “consisting,” or “consisting essentially” provides direct support for replacement to any of the other transition term not specifically used.
  • a list of constructs, molecules, method steps, kits, or compositions described with respect to a fusion protein, construct, composition, or method is intended to and doesfind direct support for embodiments related to fusion proteins, constructs, compositions, formulations, and methods 11 CYTX-115-PCT 4862-0152WO1 described in any other part of this disclosure, even if those fusion proteins, constructs, method steps, active agents, kits, or compositions are not re-listed in the context or section of that embodiment or aspect.
  • the terms “cleavable moiety” and “CM” are used interchangeably herein to refer to a polypeptide, the amino acid sequence of which comprises a substrate for a protease.
  • cleavable moieties that are suitable for use in the activatable IL12 fusion proteins and AICs herein include any of the protease substrates that are known the art. Illustrative cleavable moieties are described in more detail below. [0069]
  • the terms “masking moiety” or “MM” are used interchangeably herein to refer to a peptide or protein that, when positioned proximal to the p35 and/or p40 domain of IL12, interferes with binding of the IL12 to its receptor, thereby reducing or inhibiting one or more activities of an activatable IL12 fusion protein or construct of the present disclosure.
  • a MM when positioned proximal to IL12 in an activatable IL12 fusion protein or AIC, a MM interferes with binding of the IL12 to its binding partner (e.g., its receptor).
  • “Masking efficiency” refers to the activity (e.g., EC50) of the (uncleaved) activatable IL12 fusion proteins and AICs divided by the activity of a control interleukin-12, wherein the control interleukin-12 may be a cleavage product of the activatable IL12 fusion protein or AIC, or alternatively, a recombinant IL12.
  • An activatable IL12 fusion protein or AIC having a reduced level of at least one interleukin-12 activity has a masking efficiency that is greater than 1.5, 2, 3, 4, 5, 6, 7, 8, 9, or 10.
  • the activatable IL12 fusion proteins or AICs described herein have a masking efficiency that is greater than 10, greater than 100, greater than 1000, or greater than 5000.
  • the activatable IL12 fusion protein or AIC has a masking efficiency that is about 10 to about 1000, or about 10 to about 500, or about 50 to about 250, or about 50 to about 100, as measured by the ratio of the EC50 of the (uncleaved) activatable IL12 fusion protein or AIC to the EC50 of control interleukin12 in IL-2/IL-15 responsive HEK293 cells.
  • a masking efficiency that is about 10 to about 1000, or about 10 to about 500, or about 50 to about 250, or about 50 to about 100, as measured by the ratio of the EC50 of the (uncleaved) activatable IL12 fusion protein or AIC to the EC50 of control interleukin12 in IL-2/IL-15 responsive HEK293 cells.
  • continuous in the context of an amino acid sequences means two or more adjacent amino acids in the same order from the N- to C-terminal direction.
  • Activatable when used in reference to a activatable IL12 fusion protein or construct, refers to an activatable IL12 fusion protein or construct that exhibits afirst level of one or more activities, whereupon exposure to a condition that causes cleavage of one or more cleavable moieties results in the generation of an activatable IL12 fusion protein or construct that exhibits a 12 CYTX-115-PCT 4862-0152WO1 second level of the one or more activities, where the second level of activity is greater than thefirst level of activity.
  • activities include any of the exemplary activities of an interleukin-12 described herein or known in the art.
  • an activatable interleukin 12 (IL12) fusion protein comprises one or more polypeptide chains and an activatable IL12 construct (“AIC”) comprises two polypeptide chains.
  • “Mature cytokine polypeptide” refers herein to a cytokine polypeptide that lacks a signal sequence.
  • a cytokine polypeptide e.g., an interleukin-12 polypeptide
  • the activatable IL12 fusion proteins or constructs of the present disclosure may include a mature IL12 sequence in some aspects.
  • the activatable IL12 fusion proteins or constructs of the present disclosure may include a mature IL12 sequence and, additionally, a signal sequence. In some aspects, the activatable IL12 fusion proteins or constructs of the present disclosure may include sequences disclosed herein, including or lacking the signal sequences recited herein.
  • the terms “dimerization domain” and “DD” are used interchangeably herein to refer to one member of a pair of dimerization domains, wherein each member of the pair is capable of binding to the other via one or more covalent or non-covalent interactions.
  • Thefirst DD and the second DD may be the same or different. Exemplary DDs suitable for use as DD1 and or DD2 are described in more detail herein below.
  • a polypeptide such as a cytokine (e.g., IL12) or an Fc domain
  • cytokine e.g., IL12
  • Fc domain may be a “wild-type” polypeptide (i.e., a naturally-existing polypeptide) or a “variant” of the wild-type polypeptide.
  • a variant may be a polypeptide modified by substitution, insertion, deletion and/or addition of one or more amino acids of the wild-type polypeptide, provided that the variant retains the basic function or activity of the wild-type polypeptide.
  • a variant may have altered (e.g., increased or decreased) function or activity compared with the wild-type polypeptide.
  • the variant may be a functional fragment of the wild-type polypeptide.
  • the term “functional fragment” means that the sequence of the polypeptide (e.g., IL12) may include fewer amino acids than the full-length polypeptide sequence, but sufficient polypeptide chain length to confer activity (e.g., IL12 activity).
  • the term “at least [a certain] % identical to” in the context of two or more nucleic acid or amino acid sequences means that the two or more sequences have nucleotides or amino acid residues in common in the given percent when compared and aligned for maximum 13 CYTX-115-PCT 4862-0152WO1 correspondence over a comparison window or designated sequences of nucleic acids or amino acids (i.e.
  • sequences have at least 90 percent (%) identity). Percent identity of nucleic acid or amino acid sequences can be measured using a BLAST sequence comparison algorithm with default parameters, or by manual alignment and visual inspection (see e.g. blast.ncbi.nlm.nih.gov/Blast.cgi). Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared.
  • the % sequence identity of a given amino acid sequence A to, with, or against a given amino acid sequence B is calculated as follows: 100 times the fraction X/Y where X is the number of amino acid residues scored as identical matches by the sequence in that program’s alignment of A and B, and where Y is the total number of amino acid residues in B. It will be appreciated that where the length of amino acid sequence A is not equal to the length of amino acid sequence B, the % sequence identity of A to B will not equal the % sequence identity of B to A.
  • polypeptide and “recombinant polypeptide” are used interchangeably herein to refer to a polymer of amino acids that exists in a form that is not found in nature.
  • a “protein” can be a polymer of amino acids, but can also be a complex of two or more polymers of amino acids assembled into a quaternary structure.
  • Polypeptides employed herein may be encoded by cDNA, recombinant RNA, recombinant DNA, or a polynucleotide of synthetic origin or some combination thereof.
  • isolated polypeptide means a polypeptide of cDNA, recombinant RNA, or synthetic origin, or some combination thereof, which by virtue of its origin, or source of derivation, the “isolated polypeptide” is substantially free of endogenously expressed constituents of a host cell, such as a mammalian cell or, in the case of a cell-free expression system, substantially free of cell- free expression reagents and does not occur in nature.
  • the isolated polypeptide may be disposed in a complex comprising two or more polypeptides including wherein the complex comprises IL12.
  • a “polynucleotide” as used herein shall mean a polymer of nucleotides, such as, for example, a deoxyribonucleic acid (DNA), cDNA, a ribonucleic acid (RNA), a polynucleotide of synthetic origin, and the like, or some combination thereof.
  • nucleic acid sequence encoding a protein includes all nucleotide sequences that are degenerate versions of each other and thus encode the same amino acid sequence. Persons of ordinary skill in the art can convert amino acid sequences to derive sequences of nucleic acids encoding the amino acid sequences using automated tools (for example, bioinformatics.org/sms2/rev_trans.html).
  • N-terminally when referring to a position of afirst domain or sequence relative to a second domain or sequence in a polypeptide primary amino acid sequence, means that thefirst domain or sequence is located closer to the N-terminus of the polypeptide primary amino acid sequence than the second domain or sequence.
  • first domain or sequence there may be additional sequences and/or domains between thefirst domain or sequence and the second domain or sequence.
  • C-terminally when referring to a position of afirst domain or sequence relative to a second domain or sequence in a polypeptide primary amino acid sequence, means that thefirst domain or sequence is located closer to the C-terminus of the polypeptide primary amino acid sequence than the second domain or sequence.
  • Exogenous refers to any material introduced from or originating from outside a cell, a tissue, or an organism that is not produced by or does not originate from the same cell, tissue, or organism in which it is being introduced.
  • linker refers to amino acid sequences that connect or link two polypeptide sequences, e.g., that link two polypeptide domains. Exemplary linkers are described in more detail below.
  • transduced,” “transfected,” or “transformed” refer to a process by which an exogenous nucleic acid is introduced or transferred into a cell.
  • a “transduced,” “transfected,” or “transformed” cell is one that has been transduced, transfected, or transformed with exogenous nucleic acid (e.g., a vector) that includes an exogenous nucleic acid encoding any of the activatable IL12 fusion proteins or constructs described herein.
  • exogenous nucleic acid e.g., a vector
  • Nucleic acid refers to a deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), or a combination thereof, in either a single- or double-stranded form.
  • nucleic acid Unless specifically limited, the term encompasses nucleic acids containing known analogues of natural nucleotides that have similar binding properties as the reference nucleotides. Unless otherwise indicated, a particular nucleic acid sequence also implicitly encompasses complementary sequences as well as the sequence explicitly indicated.
  • the nucleic acid is DNA. In some aspects of any of the nucleic acids described herein, the nucleic acid is RNA.
  • the phrase “specifically binds” means that the activatable IL12 fusion protein or construct binds to its receptor or target and does not react with other polypeptides, or binds at much lower affinity, e.g., about or greater than 10 -6 M.
  • Activatable IL12 Fusion Proteins refers to ameliorating at least one symptom of a disorder.
  • AICs activatable IL12 fusion proteins or constructs (AICs) that comprise an interleukin 12 (IL12), a cleavable moiety (CM), and a masking moiety (MM), in which the IL12 comprises an IL12 ⁇ (p35) domain and an IL12 ⁇ (p40) domain.
  • IL12 interleukin 12
  • CM cleavable moiety
  • MM masking moiety
  • the p40 domain comprises the sequence: IWELKKDVYVVELDWYPDAPGEMVVLTCDTPEEDGITWTLDQSSEVLGSGKTLTIQVK EFGDAGQYTCHKGGEVLSHSLLLLHKKEDGIWSTDILKDQKEPKNKTFLRCEAKNYSGR FTCWWLTTISTDLTFSVKSSRGSSDPQGVTCGAATLSAERVRGDNKEYEYSVECQEDSA CPAAEESLPIEVMVDAVHKLKYENYTSSFFIRDIIKPDPPKNLQLKPLKNSRQVEVSWEY PDTWSTPHSYFSLTFCVQVQGKSKREKKDRVFTDKTSATVICRKNASISVRAQDRYYSS SWSEWASVPCS (SEQ ID NO: 312).
  • the p40 domain comprises the sequence: MWELEKDVYVVEVDWTPDAPGETVNLTCDTPEEDDITWTSDQRHGVIGSGKTLTITVK EFLDAGQYTCHKGGETLSHSHLLLHKKENGIWSTEILKNFKNKTFLKCEAPNYSGRFTCS WLVQRNMDLKFNIKSSSSSPDSRAVTCGMASLSAEKVTLDQRDYEKYSVSCQEDVTCP TAEETLPIELALEARQQNKYENYSTSFFIRDIIKPDPPKNLQMKPLKNSQVEVSWEYPDS WSTPHSYFSLKFFVRIQRKKEKMKETEEGCNQKGAFLVEKTSTEVQCKGGNVCVQAQD RYYNSSCSKWACVPCRVRS (SEQ ID NO: 1531).
  • the p35 domain comprises the sequence: 16 CYTX-115-PCT 4862-0152WO1 RNLPVATPDPGMFPCLHHSQNLLRAVSNMLQKARQTLEFYPCTSEEIDHEDITKDKTST VEACLPLELTKNESCLNSRETSFITNGSCLASRKTSFMMALCLSSIYEDLKMYQVEFKTM NAKLLMDPKRQIFLDQNMLAVIDELMQALNFNSETVPQKSSLEEPDFYKTKIKLCILLHA FRIRAVTIDRVMSYLNAS (SEQ ID NO: 313).
  • the p35 domain comprises the sequence: RVIPVSGPARCLSQSRNLLKTTDDMVKTAREKLKHYSCTAEDIDHEDITRDQTSTLKTCL PLELHKNESCLATRETSSTTRGSCLPPQKTSLMMTLCLGSIYEDLKMYQTEFQAINAALQ NHNHQQIILDKGMLVAIDELMQSLNHNGETLRQKPPVGEADPYRVKMKLCILLHAFSTR VVTINRVMGYLSSA (SEQ ID NO: 1530).
  • the activatable IL12 fusion proteins and AICs of the present disclosure contain masking moieties (MMs) that interfere with the binding of IL12 to its receptor.
  • the MMs bind specifically to the p40 and/or p35 domain of the IL12. In certain aspects, the MMs bind specifically to the p40 domain in the IL12.
  • the activatable IL12 fusion proteins and AICs also contain a CM, which, when cleaved, results in the MM being untethered from the rest of the activatable IL12 fusion protein or AIC, thus making the IL12 accessible to activate immune cells.
  • activatable IL12 fusion proteins and AICs exhibit a reduced level of at least one activity of IL12, but after exposure to an activation condition (e.g., protease activity, such as in a tumor microenvironment) that causes cleavage of the CM(s), the cleavage product of the activatable IL12 fusion proteins and AICs exhibit substantially restored IL12 activity.
  • an activation condition e.g., protease activity, such as in a tumor microenvironment
  • the activatable IL12 fusion proteins or constructs (AICs) that comprise an interleukin 12 (IL12) may be a chimeric fusion protein, e.g., one of p35 or p40 IL12 subunits is human and the other is derived from a species other than human (e.g., mouse).
  • activatable IL12 fusion proteins or constructs (AICs) specified as chimeric may also be the fully human equivalent.
  • the activatable IL12 fusion protein has a structure according to the formula N'-DD-L1-MM-L2-IL12-C'.
  • the activatable IL12 fusion protein has a structure according to the formula C'-DD-L1-MM-L2-IL12-N'.
  • the activatable IL12 fusion protein has a structure according to the formula N'-DD-L1-IL12-L2-MM-C'. 17 CYTX-115-PCT 4862-0152WO1 [0095]
  • each “-” between elements is a direct or indirect linkage (e.g., via a linker peptide).
  • the elements directly abut each other in amino acid sequence.
  • the elements are connected by a linker amino acid sequence.
  • the activatable IL12 fusion protein has a structure according to the formula C'-DD-L1-IL12-L2-MM-N'.
  • L1 is afirst linker or is absent
  • L2 is a second linker
  • DD is a dimerization domain
  • MM is a masking moiety
  • N' is the amino terminus
  • C' is the carboxy terminus of the activatable IL12 fusion protein
  • at least one of L1 and L2 comprises a CM.
  • L2 comprises a CM.
  • L1 comprises a CM.
  • L1 does not contain a CM.
  • L1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • L1 may comprise 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids.
  • L2 comprises about 20 to about 60 amino acids, about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids.
  • L2 may comprise 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 amino acids.
  • the activatable IL12 fusion protein or AIC has about 100-fold to about 1000-fold (e.g., about 200-fold, about 300-fold, about 400 fold, about 500- fold, about 600-fold, about 700-fold, about 800-fold, or about 900-fold) less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay.
  • activatable IL12 fusion protein and AICs according to these structural formulae are shown in FIGs. 1A-1K.
  • the activatable IL12 fusion protein or AIC has a first polypeptide with a structure comprising C'-DD1-L1-MM-CM-IL12-N' and a second polypeptide comprising a DD2 dimerized to the DD1, or a first polypeptide with a structure comprising N'-DD1-L1-MM-CM- IL12-C' and a second polypeptide comprising DD2 dimerized to the DD1.
  • an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM-MM- DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. See, for example, Fig. 1A.
  • an exemplary AIC has a first polypeptide having a structural 18 CYTX-115-PCT 4862-0152WO1 arrangement of C'-p40-p35-CM-MM-DD1-N' and a second polypeptide having a structural arrangement of C'-DD2-N'.
  • the AIC has a first polypeptide having a structural arrangement of C'-p35-p40-CM-MM-DD1-N' or N'-p35-p40-CM-MM-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'.
  • the positions of the p35 and p40 subunits are reversed.
  • the CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2).
  • the activatable IL12 fusion protein or AIC has a first polypeptide comprising C'-DD1-CM1-IL12- CM2-MM-N' or a first polypeptide comprising N'-DD1-CM1-IL12-CM2-MM-C', and a second polypeptide comprising DD2 dimerized to the DD1,
  • an exemplary AIC has a first polypeptide having a structural arrangement of N'-MM-CM1-p40-p35-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. See, for example, Fig. 1B.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-MM-CM1- p40-p35-CM2-DD1-N' and a second polypeptide having a structural arrangement of C'-DD2-N'.
  • the AIC has a first polypeptide having a structural arrangement of C'-MM-CM1- p35-p40-CM2-DD1-N' or N'-MM-CM1-p35-p40-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'.
  • the positions of the p35 and p40 subunits are reversed.
  • the activatable IL12 fusion protein or AIC comprises a first half life extension moiety (EM1), a second half life extension moiety (EM2), a first linking region (LR1), a second linking region (LR2), and a third linking region (LR3).
  • the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure N'-EM1-LR1-IL12’-C' or C'- EM1-LR1-IL12’-N'; and a second polypeptide having a structure N'-EM2-LR2-IL12”-LR3-MM- C' or C'-EM2-LR2-IL12”-LR3-MM-N'.
  • EM1 is a DD and EM2 is a DD. In some aspects, EM1 and EM2 are dimerized. In some aspects, LR1, LR2, and LR3 each independently comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids amino acids.
  • the activatable IL12 fusion protein or AIC comprises a first polypeptide having a structural arrangement of C'-IL12’-CM1- DD1-N' or N'-IL12’-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM-CM2-IL12”-CM3-DD2-N' or N'-MM-CM2-IL12”-CM3-DD2-C'.
  • the 19 CYTX-115-PCT 4862-0152WO1 IL12 ⁇ is the first IL12 subunit and the IL12′′ is the second IL12 subunit.
  • an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-CM1-DD1-C' and a second polypeptide having a structural arrangement of N'-MM-CM2-p35-CM3-DD2-C'. See, for example, Fig. 1C.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-CM1-DD1-N' and a second polypeptide having a structural arrangement of C'-MM-CM2-p35-CM3-DD2-N'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35-CM1-DD1-N' or N'-p35-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM-CM2-p40-CM3-DD2-N' or N'- MM-CM2-p40-CM3-DD2-C'.
  • the activatable IL12 fusion protein or AIC comprises a first half life extension moiety (EM1), a second half life extension moiety (EM2), a first linking region (LR1), a second linking region (LR2), and a third linking region (LR3).
  • the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure N'-EM1-LR1-IL12’-LR2- MM-C' or C'-EM1-LR1-IL12’-LR2-MM-N'; and a second polypeptide having a structure N'-EM2- LR3-IL12”-C' or C'-EM2-LR3-IL12”-N'.
  • LR1, LR2, and LR3 each independently comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids amino acids.
  • the activatable IL12 fusion protein or AIC has a first polypeptide having a structural arrangement of N'-MM-CM1-IL12′′-CM2-EM1-C' or C'-MM-CM1-IL12′′-CM2-EM1-N' and a second polypeptide having a structural arrangement of N'-IL12 ⁇ -CM3-EM2-C' or C'-IL12 ⁇ -CM3-EM2- N'.
  • the IL12 ⁇ is the first IL12 subunit and the IL12′′ is the second IL12 subunit.
  • EM1 and EM2 are dimerized.
  • an exemplary AIC has a first polypeptide having a structural arrangement of N'-MM-CM1-p40-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-p35-CM3-DD2-C'. See, for example, Fig. 1D.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'- MM-CM1-p40-CM2-DD1-N' and a second polypeptide having a structural arrangement of C'-p35- CM3-DD2-N'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-MM-CM1-p35-CM2-DD1-N' or N'-MM-CM1-p35-CM2-DD1-C' and a second polypeptide having a structural arrangement of C'-p40-CM3-DD2-N' or N'-p40-CM3-DD2-C'.
  • the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure comprising N'-DD1-L1-IL12-C' or C'-DD1-L1-IL12-N'; and a second polypeptide having a structure comprising N'-DD2-L2-MM-C' or C'-DD2-L2-MM-N'.
  • DD1 and DD2 are dimerized.
  • L1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • L1 may comprise 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids.
  • L2 comprises about 20 amino acids to about 60 amino acids, about 22 amino acids to about 58 amino acids, or about 24 amino acids to about 56 amino acids.
  • L2 may comprise 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 amino acids.
  • the activatable IL12 fusion protein or AIC has afirst polypeptide having a structural arrangement of C'-IL12-CM1-DD1-N' or N'-IL12-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM-CM2-DD2-N' or N'-MM-CM2-DD2-C'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM1-DD1- C' and a second polypeptide having a structural arrangement of N'-MM-CM2-DD2-C'. See, for example, Fig. 1E.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM1-DD1-N' and a second polypeptide having a structural arrangement of C'-MM-CM2-DD2-N'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35-p40-CM1-DD1-N' or N'-p35-p40-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM-CM2-DD2-N' or N'-MM-CM2- DD2-C'.
  • the positions of the p35 and p40 subunits are reversed.
  • FIG.1F shows an AIC with a first polypeptide having a structural arrangement of N'-p40- p35-CM1-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'.
  • an AIC comprises a first polypeptide having a structural arrangement of C'-p40- p35-CM1-DD1-N' and a second polypeptide having a structural arrangement of C'-DD2-N'.
  • FIG. 1G shows an AIC with a first polypeptide having a structural arrangement of N'-p40-CM1-DD1- C' and a second polypeptide having a structural arrangement of N'-p35-CM1-DD1-C'.
  • an AIC comprises a first polypeptide having a structural arrangement of C'-p40-CM1- DD1-N' and a second polypeptide having a structural arrangement of C'-p35-CM1-DD1-N'.
  • CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2).
  • the activatable IL12 fusion protein or AIC has a first polypeptide comprising C'-DD1-CM1-MM- CM2-IL12-N' or a first polypeptide comprising N'-DD1-CM1-MM-CM2-IL12-C', and a second polypeptide comprising DD2 dimerized to the DD1.
  • an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM1-MM-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. See, for example, Fig. 1H.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35- CM1-MM-CM2-DD1-N' and a second polypeptide having a structural arrangement of C'-DD2-N'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35- p40-CM1-MM-CM2-DD1-N' or N'-p35-p40-CM1-MM-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'.
  • the positions of the p35 and p40 subunits are reversed.
  • the activatable IL12 fusion protein or AIC comprises a first masking moiety (MM1), a second masking moiety (MM2), a third linker (L3), and a fourth linker (L4).
  • the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure N'-DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2-IL12-N', and a second polypeptide having a N'-DD2-L3-MM2-L4-IL12-C' or C'-DD2-L3-MM2-L4-IL12-N',
  • L1 and L3 each independently comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • L1 and L3 may independently comprise 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids.
  • L2 and L4 each independently comprise about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids.
  • L2 and L4 may independently comprise 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, or 54 amino acids.
  • the CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2), a third cleavable moiety (CM3), and a fourth cleavable moiety (CM4).
  • CM1 first cleavable moiety
  • CM2 second cleavable moiety
  • CM3 third cleavable moiety
  • CM4 fourth cleavable moiety
  • the activatable IL12 fusion protein or AIC has a first polypeptide comprising C'- DD1-CM1-MM1-CM2-IL12-N' and a second polypeptide comprising C'-DD2-CM3-MM2-CM4- 22 CYTX-115-PCT 4862-0152WO1 IL12-N', or a first polypeptide comprising N'-DD1-CM1-MM1-CM2-IL12-C' and a second polypeptide comprising N'-DD2-CM3-MM2-CM4-IL12-C'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM1-MM-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-p40-p35-CM3-MM-CM4-DD2-C'. See, for example, Fig. 1I.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM1-MM-CM2-DD1-N' and a second polypeptide having a structural arrangement of C'-p40-p35-CM3-MM-CM4-DD2-N'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35-p40-CM1-MM-CM2-DD1-N' or N'-p35- p40-CM1-MM-CM2-DD1-C' and a second polypeptide having a structural arrangement of C'-p35- p40-CM3-MM-CM4-DD2-N' or N'-p35-p40-CM3-MM-CM4-DD2-C'.
  • the positions of the p35 and p40 subunits are reversed.
  • the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure N'-DD1-L1-MM-L2-IL12-C' or C'-DD1-L1-MM-L2-IL12-N', and a second polypeptide having a structure comprising: N'-DD2-C' or C'-DD2-N'.
  • the MM comprises a first sequence (MM’) and a second sequence (MM”), and the MM further comprises the CM within the MM sequence according to the structure comprising: MM’-CM-MM”.
  • the CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2), and a third cleavable moiety (CM3).
  • the activatable IL12 fusion protein or AIC has a first polypeptide comprising C'-DD1- CM1-MM-CM2-IL12-N' and a second polypeptide comprising N'-DD2-C' or a first polypeptide comprising N'-DD1-CM1-MM-CM2-IL12-C' and a second polypeptide comprising N'-DD2-C'.
  • the MM comprises a first sequence (MM’) and a second sequence (MM”), and the MM further comprises the CM3 within the MM sequence according to the structure comprising: MM’-CM3-MM”.
  • an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM1-MM’-CM3-MM”-CM2-DD1-C' and a second polypeptide having a structural arrangement N'-DD2-C'. See, for example, Fig.1J.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM1- MM’-CM3-MM”-CM2-DD1-N' and a second polypeptide having a structural arrangement C'- DD2-N'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35-p40-CM1-MM’-CM3-MM”-CM2-DD1-N' or N'-p35-p40-CM1-MM’-CM3-MM”- 23 CYTX-115-PCT 4862-0152WO1 CM2-DD1-C' and a second polypeptide having a structural arrangement N'-DD2-C' or C'-DD2- N'.
  • the MM is a first cleavable moiety (MM1) and the activatable IL12 fusion protein or AIC further comprises a second masking moiety (MM2) and a third linker (LR3).
  • the activatable IL12 fusion protein or AIC has a first polypeptide comprising N'- DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2-IL12-N'; and a second polypeptide having a structure N'-DD2-L3-MM2-C' or C'-DD2-L3-MM2-N'.
  • the MM1 comprises a first sequence (MM’) and a second sequence (MM”), and the MM1 further comprises the CM within the MM1 sequence according to the structure comprising: MM1’-CM-MM1”.
  • L1 and L3 each independently comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • L1 and L3 may independently comprise 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids.
  • L2 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids.
  • L2 may comprise 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, or 54 amino acids.
  • the CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2), a third cleavable moiety (CM3), and a fourth cleavable moiety (CM4).
  • the first polypeptide comprises C'-DD1-CM1-MM1-CM2-IL12-N' and the second polypeptide comprises C’DD2-CM3-MM2-N’, or the first polypeptide comprises N'-DD1-CM1-MM1-CM2-IL12-C' and the second polypeptide comprises N’-DD2-CM3-MM2-N’.
  • the MM1 comprises a first sequence (MM1’) and a second sequence (MM1”), and wherein the MM1 optionally further comprises the CM4 within the MM1 according to the structure comprising: MM1’-CM4-MM1”.
  • an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40- p35-CM1-MM1’-CM4-MM1”-CM2-DD1-C' and a second polypeptide having a structural arrangement N'-MM2-CM3-DD2-C'. See, for example, Fig.1K.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM1-MM1’-CM4-MM1”- CM2-DD1-N' and a second polypeptide having a structural arrangement C'-MM2-CM3-DD2-N'.
  • an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35- 24 CYTX-115-PCT 4862-0152WO1 p40-CM1-MM1’-CM4-MM1”-CM2-DD1-N' or N'-p35-p40-CM1-MM1’-CM4-MM1”-CM2- DD1-C' and a second polypeptide having a structural arrangement N'-MM2-CM3-DD2-C' or C'- MM2-CM3-DD2-N'.
  • the MM is an anti-p40 scFv. In some aspects, the MM is an anti-p35 scFv.
  • the MM is an antibody that binds to each of p35 and p40. In some aspects, the MM is an antibody with a first binding domain that binds to p35 and a second binding domain that binds to p40.
  • the activatable IL12 fusion proteins described in the immediately preceding paragraph may exist as monomers, their DDs make it possible for them to exist as dimers as well. For example, in one aspect, they exist as heterodimers (i.e., not as homodimers).
  • FIG.1A depicts an AIC in which one monomer follows the formula N'-p40-L1- p35-CM-MM-L2-DD-C', while the other monomer is a solitary DD, i.e., the second monomer consists of a DD.
  • This construct is illustrative of a second polypeptide that comprises a DD but does not comprise and IL12, MM, or CM substituent.
  • dimeric AICs may comprise afirst and a second polypeptide, where thefirst polypeptide may comprise SEQ ID NO: 1 and the second polypeptide may comprise SEQ ID NO: 2; or thefirst polypeptide may comprise SEQ ID NO: 7 and the second polypeptide may comprise SEQ ID NO: 8; or thefirst polypeptide may comprise SEQ ID NO: 9 and the second polypeptide may comprise SEQ ID NO: 10; or thefirst polypeptide may comprise SEQ ID NO: 11 and the second polypeptide may comprise SEQ ID NO: 12; or thefirst polypeptide may comprise SEQ ID NO: 13 and the second polypeptide may comprise SEQ ID NO: 14; or thefirst polypeptide may comprise SEQ ID NO: 15 and the second polypeptide may comprise SEQ ID NO: 16; or thefirst polypeptide may comprise SEQ ID NO: 17 and the second polypeptide may comprise SEQ ID NO: 18.
  • the AIC is a dimer comprising afirst polypeptide with a structure N'- DD1-L1-p40-C' or C'-DD1-L1-p40-N', and a second polypeptide with a structure N'-DD2-L2-p35- L3-MM-C' or C'-DD2-L2-p35-L3-MM-N'.
  • the AIC is a dimer comprising afirst polypeptide with a structure N'- DD1-L1-p35-C' or C'-DD1-L1-p35-N' and a second polypeptide with a structure N'-DD2-L2-p40- L3-MM-C' or C'-DD2-L2-p40-L3-MM-N'.
  • each of L1, L2, and L3 independently comprises a CM; DD1 is afirst dimerization domain and DD2 is a second 25 CYTX-115-PCT 4862-0152WO1 dimerization domain, where DD1 and DD2 are dimerized; MM is an scFv or peptide masking moiety; N' is the AIC amino terminus; and C' is the AIC carboxy terminus.
  • the AIC has about 50-fold to about 1000-fold (e.g., about 100-fold, about 200-fold, about 300-fold, about 400 fold, about 500-fold, about 600-fold, about 700-fold, about 800-fold, or about 900-fold) less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay.
  • AICs according to these structural formulae are shown in FIGs. 1C and 1D.
  • AICs may comprise afirst and a second polypeptide, where thefirst polypeptide may comprise SEQ ID NO: 3 and the second polypeptide may comprise SEQ ID NO: 4; or thefirst polypeptide may comprise SEQ ID NO: 19 and the second polypeptide may comprise SEQ ID NO: 20; or thefirst polypeptide may comprise SEQ ID NO: 21 and the second polypeptide may comprise SEQ ID NO: 22; or thefirst polypeptide may comprise SEQ ID NO: 23 and the second polypeptide may comprise SEQ ID NO: 24; or thefirst polypeptide may comprise SEQ ID NO: 25 and the second polypeptide may comprise SEQ ID NO: 26; or thefirst polypeptide may comprise SEQ ID NO: 27 and the second polypeptide may comprise SEQ ID NO: 28; or thefirst polypeptide may comprise SEQ ID NO: 29 and the second polypeptide may comprise SEQ ID NO: 30; or thefirst polypeptide may comprise SEQ ID NO: 31 and the second polypeptide may comprise SEQ ID NO:
  • the AIC is a dimer comprising afirst polypeptide with a structure N'- DD1-L1-IL12-C' or C'-DD1-L1-IL12-N' and a second polypeptide with a structure N'-DD2-L2- 26 CYTX-115-PCT 4862-0152WO1 MM-C' or C'-DD2-L2-MM-N'.
  • each of L1 and L2 independently is a CM; DD1 is afirst dimerization domain and DD2 is a second dimerization domain; DD1 is more proximal to the p35 domain than to the p40 domain; DD1 and DD2 are dimerized; MM is an anti- p40 scFv; N' is the AIC amino terminus; and C' is the AIC carboxy terminus.
  • the AIC has about 10-fold to about 50-fold (e.g., about 20-fold, about 30-fold, or about 40-fold) less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay.
  • an AIC comprises afirst and a second polypeptide, where thefirst polypeptide comprises SEQ ID NO: 5 and the second polypeptide comprises SEQ ID NO: 6.
  • activatable IL12 fusion proteins or AICs of the present disclosure selectively activate upon exposure to diseased tissue, and not in normal tissue. Following activation of the activatable IL12 fusion protein or AIC upon cleavage of the CM(s), IL12 activity is restored indicating that released MM(s) are not bound to the IL12 after cleavage and do not interfere or compete with the IL12 for binding to its target.
  • an MM Before activation, the MM inhibits the IL12 from binding to its receptor. When activated (i.e., when the CM is cleaved by a protease), however, the MM does not substantially or significantly interfere with IL12 binding to its cognate receptor.
  • An MM may be coupled to the IL12 either directly or indirectly, e.g., via one or more linkers. Alternatively, an MM may be coupled, either directly or indirectly, to a component of the activatable IL12 fusion protein or AIC that is not the IL12. For example, the MM may be coupled, either directly or indirectly, with a DD.
  • the MM is positioned (e.g., proximal to the IL12 to be masked) so as to mask the IL12.
  • the activatable IL12 fusion protein or AIC is characterized by a reduction in at least one activity of IL12.
  • the at least one activity is the binding affinity (KD) of the IL12 for its cognate receptor as determined using surface plasmon resonance (e.g., performed in phosphate buffered saline at 25°C).
  • the at least one activity is the level of proliferation of T cells or NK cells.
  • the activatable IL12 fusion protein or AIC is characterized by at least a 2-fold reduction in at least one IL12 activity as compared to the control level of the at least one IL12 activity.
  • the activatable IL12 fusion protein or AIC is characterized by at least a 5-fold reduction in at least one activity of the IL12 as compared to the control level of the at least one activity of the IL12.
  • the activatable IL12 fusion protein or AIC is characterized by at least a 10-fold reduction in at least one activity of the IL12 as compared to the control level of the at least one activity of the IL12.
  • the activatable IL12 fusion protein or AIC is characterized by at least a 1- to 20-fold reduction, a 200- to 500-fold reduction, a 300- to 500-fold reduction, a 400- to 500-fold reduction, a 500- to 600-fold reduction, a 600- to 700-fold reduction, a 150- to 1000-fold reduction, a 100- to 1500- fold reduction, a 200- to 1500-fold reduction, a 300- to 1500-fold reduction, a 400- to 1500-fold reduction, a 500- to 1500-fold reduction, a 1000- to 1500-fold reduction, a 100- to 1000-fold reduction, a 200- to 1000-fold reduction, a 300- to 1000-fold reduction, a 400- to 1000-fold reduction, a 500- to 1000-fold reduction, a 100- to 500-fold reduction, a 20- to 50-fold reduction, a 30- to 50-fold reduction, a 40- to 50-fold reduction, a 100- to 400-fold reduction, a 200-fold reduction,
  • an activatable IL12 fusion protein or AIC of the present disclosure generates a cleavage product that comprises the at least one activity of the IL12.
  • the control level is an EC50 value of the wild type 28 CYTX-115-PCT 4862-0152WO1 mature IL12, and wherein ratio of EC50 (cleavage product) to EC50 (wild type control level) is less than about 10, or less than about 9, or less than about 8, or less than about 7, or less than about 6, or less than about 5, or less than about 4, or less than about 3, or less than about 2, or less than about 1.5, or equal to about 1.
  • the % activation of IL12 is at least about 10%. Percent activation is calculated as the EC50 of the recombinant IL-12 divided by the EC50 of the cleavage product times 100, where each EC50 is determined in accordance with the method of Example 3. In some aspects the % activation is at least about 15%, 20%, 25%, 30%, 40%, 45%, 50%, 60%, 70%, 75%, 80%, 85%, or 90%.
  • the control level of the at least one activity of the IL12 is the activity of the IL12 released from the activatable IL12 fusion protein or AIC following cleavage of the CM by the protease(s) (the “cleavage product”).
  • control level of the at least one activity of the IL12 is the activity of a corresponding wild type mature IL12 (e.g., recombinant wild type mature IL12).
  • incubation of the activatable IL12 fusion protein or AIC with the protease yields a cleavage product, where one or more activities of IL12 of the cleavage product are greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC (when uncleaved).
  • one or more activities of IL12 of the cleavage product are at least 1.5-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC.
  • one or more activities of IL12 of the cleavage product are at least 2-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC. In some aspects, one or more activities of IL12 of the cleavage product are at least 5-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC. In some aspects, one or more activities of IL12 of the cleavage product are at least 10-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC.
  • one or more 29 CYTX-115-PCT 4862-0152WO1 activities of IL12 of the cleavage product are at least 20-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC.
  • one or more activities of IL12 of the cleavage product are at least 1- to 20-fold greater, 2- to 20-fold greater, 3- to 20-fold greater, 4- to 20-fold greater, 5- to 20-fold greater, 10- to 20-fold greater, 15- to 20-fold greater, 1- to 15-fold greater, 2- to 15-fold greater, 3- to 15-fold greater, 4- to 15-fold greater, 5- to 15-fold greater, 10- to 15-fold greater, 1- to 10-fold greater, 2- to 10-fold greater, 3- to 10-fold greater, 4- to 10-fold greater, 5- to 10-fold greater, 1- to 5-fold greater, 2- to 5-fold greater, 3- to 5-fold greater, 4- to 5-fold greater, 1- to 4-fold greater, 2- to 4-fold greater, 3- to 4-fold greater, 1- to 3-fold greater, 2- to 3-fold greater, or 1- to 2-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC.
  • an activatable IL12 fusion protein or AIC may include a signal sequence.
  • Signal sequences are not particularly limited. Some non-limiting examples of signal sequences include, e.g., MRAWIFFLLCLAGRALA (SEQ ID NO: 99), MALTFALLVALLVLSCKSSCSVG (SEQ ID NO: 100), METDTLLLWVLLLWVPGSTG (SEQ ID NO: 288).
  • MRAWIFFLLCLAGRALA SEQ ID NO: 99
  • MALTFALLVALLVLSCKSSCSVG SEQ ID NO: 100
  • METDTLLLWVLLLWVPGSTG SEQ ID NO: 288).
  • the present disclosure includes activatable IL12 fusion proteins that consist of a single polypeptide chain. In some aspects, this single polypeptide chain possesses a DD, but nonetheless exists and functions in an undimerized state.
  • these activatable IL12 fusion proteins have: at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1; at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 7; at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least
  • the AICs comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 31 CYTX-115-PCT 4862-0152WO1 99%, or even 100% sequence identity to SEQ ID NO: 2
  • the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 3 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 4; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%
  • the AIC comprises afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 5 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 6.
  • the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1362 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 8; in some aspects, the AIC comprises: afirst polypeptide
  • a AIC polypeptide may comprise at least about 60%, at least about 65%, at least about 70%, at least about 75%, at 44 CYTX-115-PCT 4862-0152WO1 least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to a sequence according to SEQ ID NOs: 1–54 or 1532, 1533, 1536, 1537, 1540, 1541, 1544, 1545, 1548, 1550, 1552, 1553, 1556, 1557, 1560, 1561, 1564, 1565, 1568, 1569, 1572, 1573, 1576, 1577, 1580, 1581, 1584, 1585, 1588, 1590, 1592, 1593, 1596, 1597, 1600, 1601, 1604, 1605, 160
  • one or both of thefirst and second polypeptides each independently further comprise additional elements, such as, for example, one or more linkers, spacers, and the like.
  • additional elements are described below in more detail.
  • the AIC structure was discovered to be highly effective at reducing IL12 activity in a way that does not lead to substantially impaired activity after activation.
  • the IL12 activity in the AIC may be reduced by both the structure of the AIC (e.g., the dimer structure) and the MMs.
  • the activation condition for the AICs described herein is exposure to one or more proteases that cleave the MM from the IL12.
  • the one or more proteases may cleave the CM between the IL12 and the MM. Additionally or alternatively, the one or more proteases may cleave the CM between the IL12 and the DD.
  • the CM may also be provided within the MM sequence according to the structure MM’-CM-MM” such that MM’-CM-MM” has masking activity and the one or more proteases may cleave the CM within the MM. As demonstrated in the Examples, activation of the AIC resulted in substantial recovery of IL12 activity.
  • an AIC of the present disclosure when in the presence of a natural binding partner of the IL12 (e.g., its receptor), either no binding or substantially no binding of the IL12 to its natural binding partner is observed.
  • a natural binding partner of the IL12 e.g., its receptor
  • the mask efficiency assay may involve measurement of the affinity of IL12 binding to a cell surface displaying a candidate masking moiety by, for example, FACS.
  • Another non-limiting exemplary assay includes assessing the 45 CYTX-115-PCT 4862-0152WO1 ability of a masking moiety to inhibit IL12 binding to its binding partner at therapeutically relevant concentrations and times.
  • an immunosorbant assay to measure the time- dependent binding of proprotein binding to its binding partner has been developed as described in US20200308243, incorporated herein by reference.
  • Half-life extending moieties (EMs) [00132]
  • the activatable IL12 fusion protein or AIC of the present disclosure may include one or more EMs.
  • the EM sterically interferes with binding of the IL12 fusion protein or AIC to its target.
  • An EM may inhibit or block the activity of the IL12 due to its proximity and comparative size to the IL12.
  • Steric inhibition of the IL12 can be removed by spatially separating the IL12 from the EM, such as by cleaving the IL12 fusion protein or AIC at a site between the EM and the IL12.
  • the EM does not bind specifically to the IL12 fusion protein or AIC.
  • the EM upon cleavage of a CM in the IL12 fusion protein or AIC, the EM does not sterically interfere with binding of the IL12 fusion protein or AIC to the target.
  • the EM when the CM is cleaved, the EM can dissociate from IL12, and the IL12 can then activate its receptor.
  • the EM is selected from the group consisting of an albumin binding peptide, a fibrinogen binding peptide, a fibronectin binding peptide, a hemoglobin binding peptide, a transferrin binding peptide, an immunoglobulin domain binding peptide, and other serum protein binding peptides.
  • the EM is a soluble, globular protein.
  • the EM is a protein that circulates in the bloodstream.
  • the EM is selected from the group consisting of an albumin, a fibrinogen, a fibronectin, a hemoglobin, a transferrin, an immunoglobulin domain, and other serum proteins.
  • the EM comprises a polyalkylene glycol polymer (also known as polyalkylene oxides), e.g., a poly(ethylene glycol) (PEG)-containing moiety, hexa-hat GST (glutathione S-transferase) glutathione affinity, Calmodulin-binding peptide (CBP), latency associated protein (LAP), Strep-tag, Cellulose Binding Domain, Maltose Binding Protein, S-Peptide Tag, Chitin Binding Tag, Immuno-reactive Epitopes, Epitope Tags, E2Tag, HA Epitope Tag, Myc Epitope, FLAG Epitope, AU1 and AU5 Epitopes, Glu-Glu Epitope, KT3
  • PEG poly
  • the EM may contain an alpha- or omega-dihydroxylpoly(ethylene glycol), can also be represented as HO- PEG-OH, where it is understood that the term (“PEG”) or (“-PEG-”) represents the following structural unit: 46 CYTX-115-PCT 4862-0152WO1 —CH 2 CH 2 —(CH 2 CH 2 O) n —CH 2 CH 2 —, where n may range from about 1,000 to about 50,000.
  • PEG may be used as methoxy-PEG-OH, or mPEG, in which one terminus is the relatively inert methoxy group, while the other terminus is a hydroxyl group that is subject to ready chemical modification.
  • the EM is an albumin binding peptide comprising the amino acid sequence QRLMEDICLPRWGCLWEDDF (SEQ ID NO: 1424).
  • the EM comprises an albumin binding peptide fused to a flexible portion (FP1) having the sequence GSSGGSGGSGGSGGGSGGGSGG (SEQ ID NO: 1425).
  • one or more EMs include members of a pair, e.g., a dimerization domain (DD), as described herein.
  • one or more EMs include one or more Fc domains, as described herein.
  • AICs include EMs comprising a pair of Fc domains that form a homodimer, i.e., identical Fc domains interact with each other to form a dimer.
  • AICs include EMs comprising Fc domains that form a heterodimer, i.e., a dimer of Fc domains that are not identical in amino acid sequence.
  • an Fc domain comprises an Fc hinge domain, or sequence or truncation variant thereof. For example, for heterodimerization, a knobs- into-holes strategy is used.
  • knob and hole interaction will favor heterodimer formation, whereas the knob-knob and the hole-hole interaction will hinder homodimers formation due to the steric clash and deletion of favorable interactions, respectively.
  • one or more EMs each include a total of about 5 amino acids to about 250 amino acids, about 5 amino acids to about 200 amino acids, about 5 amino acids to about 180 amino acids, about 5 amino acids to about 160 amino acids, about 5 amino acids to about 140 amino acids, about 5 amino acids to about 120 amino acids, about 5 amino acids to about 100 amino acids, about 5 amino acids to about 80 amino acids, about 5 amino acids to about 60 amino acids, about 5 amino acids to about 40 amino acids, about 5 amino acids to about 20 amino acids, about 5 amino acids to about 10 amino acids, about 10 amino acids to about 250 amino acids, about 10 amino acids to about 200 amino acids, about 10 amino acids to about 180 amino acids, about 10 amino acids to about 160 amino acids, about 10 amino acids to about 140 amino acids, about 10 amino acids to about 120 amino acids, about 10 amino acids to about 100 amino acids, about 10 amino acids to about 80 amino acids, about 10 amino acids to about 60 amino acids, 47 CYTX-115-PCT 4862-0152WO1 about 10 amino acids to about 40 amino acids
  • the EM is C-terminal to p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, the EM is C-terminal to p40 subunit of IL12 in the activatable IL12 48 CYTX-115-PCT 4862-0152WO1 fusion protein or AIC. In one aspect, the EM is N-terminal to p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, the EM is N-terminal to p40 subunit of IL12 in the activatable IL12 fusion protein or AIC.
  • a linker is provided between the EM and the p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a linker is provided between the EM and the p40 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a CM is provided between the EM and the p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a CM is provided between the EM and the p40 subunit of IL12 in the activatable IL12 fusion protein or AIC.
  • a MM is provided between the EM and the p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a MM is provided between the EM and the p40 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a CM, a linker, and/or a MM is/are provided between the EM and the p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a CM, a linker, and/or a MM is/are provided between the EM and the p40 subunit of IL12 in the activatable IL12 fusion protein or AIC.
  • the activatable IL12 fusion protein or AIC of the present disclosure may include one or more DDs. Any of a variety of dimerization domains that are known in the art are suitable for use in the practice of the present invention.
  • Suitable DDs include both polymeric (e.g., a synthetic polymer, a polypeptide, a polynucleotide, and the like) and small molecule (non-polymeric moieties having a molecular weight of less than about 1 kDa, and sometimes less than about 800 Daltons) types of moieties.
  • the DD1 and the DD2 are members of a pair selected from the group of: barnase and barnstar; a PKA and an AKAP; adapter/docking tag molecules based on mutated Rnase I fragments; a pair of antigen-binding domains (e.g., a pair of single domain antibodies); soluble N-ethyl-maleimide sensitive factor attachment protein receptors (SNARE) modules based on interactions of the proteins syntaxin, synaptotagmin, synaptobrevin, and SNAP25; a single domain antibody (sdAb) and corresponding epitope; an antigen-binding domain (e.g., a single chain antibody such as a single chain variable fragment (scFv), a single domain antibody, and the like) and a corresponding epitope; coiled coil polypeptide structures (e.g., Fos- Jun coiled coil structures, acid/base coiled-coil helices, Glu
  • non-naturally occurring epitopes include, for example, a non-naturally occurring peptide, such as, for example, a poly-His peptide (e.g., a His tag, and the like).
  • a non-naturally occurring peptide such as, for example, a poly-His peptide (e.g., a His tag, and the like).
  • the DD1 and the DD2 are a pair of Fc domains.
  • an “Fc domain” refers to a contiguous amino acid sequence of a portion of a single heavy chain of an immunoglobulin that excludes its variable domains, e.g., the hinge, the CH2-CH3 domains of IgG, IgA, or IgD, or the CH2-CH3-CH4 domains of IgE or IgM and engineered variants thereof.
  • the pair of Fc domains is a pair of human Fc domains (e.g., a pair of wild type human Fc domains).
  • the human Fc domains are human IgG1 Fc domains (e.g., wildtype human IgG1 Fc domains), human IgG2 Fc domains (e.g., wildtype human IgG2 Fc domains), human IgG3 Fc domains (e.g., wildtype human IgG3 Fc domains), or human IgG4 Fc domains (e.g., wildtype human IgG4 Fc domains).
  • the human Fc domains comprise a sequence that is at least 80% identical (e.g., at least 82%, at least 84%, at least 85%, at least 86%, at least 88%, at least 90%, at least 92%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical) to SEQ ID NO: 2.
  • the pair of Fc domains comprises a knob mutant and a hole mutant of a Fc domain.
  • the knob and hole mutants may interact with each other to facilitate the dimerization.
  • the knob and hole mutants comprises one or more amino acid modifications within the interface between two Fc domains (e.g., in the CH3 domain).
  • the human Fc domains comprise the mutation N297Q, N297A, or N297G; in some aspects the human Fc domains comprise a mutation at position 234 and/or 235, for example L235E, or L234A and L235A (in IgG1), or F234A and L235A (in IgG4); in some aspects the human Fc domains are IgG2 Fc domains that comprise the mutations V234A, G237A, P238S, H268Q/A, V309L, A330S, or P331S, or a combination thereof (all according to EU numbering). Additional examples of engineered human Fc domains are known to those skilled in the art.
  • combinations of mutated amino acids are also known in the art, such as, but not limited to a combination of mutations in amino acids 234, 235, and 331, such as L234F, L235E, and P331S or a combination of amino acids 318, 320, and 322, such as E318A, K320A, and K322A.
  • engineered Fc domains include F243L/R292P/Y300L/V305I/P396 IgG1; S239D/I332E IgG1; S239D/I332E/A330L IgG1; S298A/E333A/K334A; in one heavy chain, L234Y/L235Q/G236W/S239M/H268D/D270E/S298A IgG1, and in the opposing heavy chain, D270E/K326D, A330M/K334E IgG; G236A/S239D/I332E IgG1; K326W/E333S IgG1; S267E/H268F/S324T IgG1; E345R/E430G/S440Y IgG1; N297A or N297Q or N297G IgG1; L235E IgG1; L234A/
  • the engineered Fc domain comprises one or more substitutions selected from the group consisting of N297A IgG1, N297Q IgG1, and S228P IgG4.
  • the dimerization domain is an IgG Fc region wherein the upper hinge residues have been deleted.
  • the Fc is a variant wherein N-terminal sequences EPKSCDKTHT (SEQ ID NO: 55), ERK, ELKTPLGDTTHT (SEQ ID NO: 56), or ESKYGPP (SEQ ID NO: 57) have been deleted.
  • the DD, or the DD1 and/or DD2 can further include a serum half-life extending moiety (e.g., polypeptides that bind serum proteins, such as immunoglobulin (e.g., IgG) or serum albumin (e.g., human serum albumin (I)).
  • a serum half-life extending moiety e.g., polypeptides that bind serum proteins, such as immunoglobulin (e.g., IgG) or serum albumin (e.g., human serum albumin (I)).
  • half-life extending moieties include hexa-hat GST (glutathione S-transferase) glutathione affinity, Calmodulin-binding peptide (CBP), Strep-tag, Cellulose Binding Domain, Maltose Binding Protein, S-Peptide Tag, Chitin Binding Tag, Immuno-reactive Epitopes, Epitope Tags, E2Tag, HA Epitope Tag, Myc Epitope, FLAG Epitope, AU1 and AU5 Epitopes, Glu-Glu Epitope, KT3 Epitope, IRS Epitope, Btag Epitope, Protein Kinase-C Epitope, and VSV Epitope.
  • CBP Calmodulin-binding peptide
  • Strep-tag Strep-tag
  • Cellulose Binding Domain Maltose Binding Protein
  • S-Peptide Tag Chitin Binding Tag
  • Immuno-reactive Epitopes Epitope Tags
  • DD1 and/or DD2 each include a total of about 5 amino acids to about 350 amino acids, about 5 amino acids to about 250 amino acids, about 5 amino acids to about 200 amino acids, about 5 amino acids to about 180 amino acids, about 5 amino acids to about 160 amino acids, about 5 amino acids to about 140 amino acids, about 5 amino acids to about 120 amino acids, about 5 amino acids to about 100 amino acids, about 5 amino acids to about 80 amino acids, about 5 amino acids to about 60 amino acids, about 5 amino acids to about 40 amino acids, about 5 amino acids to about 20 amino acids, about 5 amino acids to about 10 amino acids, about 10 amino acids to about 350 amino acids, about 10 amino acids to about 250 amino acids, about 10 amino acids to about 200 amino acids, about 10 amino acids to about 180 amino acids, about 10 amino acids to about 160 amino acids, about 10 amino acids to about 140 amino acids, about 10 amino acids to about 120 amino acids, about 10 amino acids to about 100 amino acids, about 10 amino acids to about 80 amino acids, about 10 amino acids to about 60 amino acids, about 10
  • DD1 and DD2 are each an Fc domain that comprises a portion of the hinge region that includes two cysteine residues, a CH2 domain, and a CH3 domain. In some aspects, DD1 and DD2 are each an Fc domain whose N-terminus is thefirst cysteine residue in the hinge region reading in the N- to C- direction (e.g., Cysteine 226 of human IgG1 or IgG4, using EU numbering).
  • thefirst monomer and/or the second monomer can each include a total of about 150 amino acids to about 800 amino acids, about 150 amino acids to about 750 amino acids, about 150 amino acids to about 700 amino acids, about 150 amino acids to about 650 amino 53 CYTX-115-PCT 4862-0152WO1 acids, about 150 amino acids to about 600 amino acids, about 150 amino acids to about 550 amino acids, about 150 amino acids to about 500 amino acids, about 150 amino acids to about 450 amino acids, about 150 amino acids to about 400 amino acids, about 150 amino acids to about 350 amino acids, about 150 amino acids to about 300 amino acids, about 150 amino acids to about 250 amino acids, about 150 amino acids to about 200 amino acids, about 200 amino acids to about 800 amino acids, about 200 amino acids to about 750 amino acids, about 200 amino acids to about 700 amino acids, about 200 amino acids to about 650 amino acids, about 200 amino acids to about 600 amino acids, about 200 amino acids to about 550 amino acids, about 200 amino acids to about 500 amino acids, about 200 amino acids to about.
  • the DD comprises an IgG Fc with a knob mutation, comprising the sequence: DSTHTCPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVD GVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPASIEKTISK AKGQPREPQVYTLPPCRDELTKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPP VLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO: 1505).
  • the DD comprises a human IgG Fc with a knob mutation, comprising the sequence: CPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEV HNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQP REPQVYTLPPCQEEMTKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLG (SEQ ID NO: 307).
  • the DD comprises an IgG Fc with a hole mutation comprising the sequence: DSTHTCPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVD GVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPASIEKTISK AKGQPREPQVCTLPPSRDELTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPV 55 CYTX-115-PCT 4862-0152WO1 LDSDGSFFLVSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSPG (SEQ ID NO: 1506).
  • the DD comprises a human IgG Fc with a hole mutation comprising the sequence: CPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEV HNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQP REPQVCTLPPSQEEMTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDG SFFLVSRLTVDKSRWQEGNVFSCSVMHEALHNRFTQKSLSLSLG (SEQ ID NO: 308).
  • the DD comprises a human IgG4 variant (S228P) with a truncated hinge region comprising the sequence: CPPCPAPEFLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEV HNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQP REPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDG SFFLYSRLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLS (SEQ ID NO: 310).
  • the DD comprises a human IgG4 variant (S228P) with a full hinge region comprising the sequence: ESKYGPPCPPCPAPEFLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWY VDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTIS KAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPP VLDSDGSFFLYSRLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLS (SEQ ID NO: 311).
  • the DD comprises a Human IgG1 sequence comprising: ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGG PSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQY NSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSR EEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDK SRWQQGNVFSCSVMHEALHNHYTQKSLSPG* (SEQ ID NO: 314), which may further comprise a lysine residue (K) at the C-terminus.
  • K lysine residue
  • the DD comprises a human IgG2 sequence comprising: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS 56 CYTX-115-PCT 4862-0152WO1 GLYSLSSVVTVPSSNFGTQTYTCNVDHKPSNTKVDKTVERKCCVECPPCPAPPVAGPSV FLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVQFNWYVDGVEVHNAKTKPREEQFNST FRVVSVLTVVHQDWLNGKEYKCKVSNKGLPAPIEKTISKTKGQPREPQVYTLPPSREEM TKNQVSLTCLVKGFYPSDISVEWESNGQPENNYKTTPPMLDSDGSFFLYSKLTVDKSRW QQGNVFSCSVMHEALHNHYTQKSLSPG* (SEQ ID NO: 315), which may further comprise a lysine residue (K) at the C
  • the DD comprises a human IgG3 sequence comprising: ASTKGPSVFPLAPCSRSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTQTYTCNVNHKPSNTKVDKRVELKTPLGDTTHTCPRCPEPKSC DTPPPCPRCPEPKSCDTPPPCPRCPEPKSCDTPPPCPRCPAPELLGGPSVFLFPPKPKDTLMI SRTPEVTCVVVDVSHEDPEVQFKWYVDGVEVHNAKTKPREEQYNSTFRVVSVLTVLHQ DWLNGKEYKCKVSNKALPAPIEKTISKTKGQPREPQVYTLPPSREEMTKNQVSLTCLVK GFYPSDIAVEWESSGQPENNYNTTPPMLDSDGSFFLYSKLTVDKSRWQQGNIFSCSVMH EALHNRFTQKSLSLSPG* (SEQ ID NO: 316), which may further comprise
  • the DD comprises a human IgG4 sequence comprising: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCPSCPAPEFLGGPSV FLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNST YRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEM TKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRW QEGNVFSCSVMHEALHNHYTQKSLSLSLG* (SEQ ID NO: 317), which may further comprise a lysine residue (K) at the C-terminus.
  • K lysine residue
  • activatable IL12 fusion proteins or AICs comprise one or more CMs.
  • a CM may be positioned between two components in an activatable IL12 fusion protein or AIC, e.g., between an IL12 and an MM, between an IL12 and a DD, and/or between an IL12 and another component in the activatable IL12 fusion protein or the AIC.
  • an MM is coupled with an IL12 via a CM, i.e., the CM is positioned between the IL12 and the MM.
  • a CM is positioned between an MM and an IL12, either directly or indirectly (e.g., via a linker). In some aspects, a CM is positioned between the IL12 and a DD, 57 CYTX-115-PCT 4862-0152WO1 either directly or indirectly (e.g., via a linker). In some aspects, the CM is positioned within the MM. [00161] Peptide or polypeptide sequences comprising any of a variety of protease substrate sequences may be employed as a CM in the activatable IL12 fusion proteins or AICs of the present disclosure. In some aspects, the CM comprises substrate(s) for two or more proteases.
  • the CM comprises a substrate for a protease that is upregulated during a disease condition, e.g., in diseased tissue.
  • the CMs herein comprise substrates for proteases that have been reported in a cancer, or in a number of cancers. See, e.g., La Roca et al., British J. Cancer 90(7):1414-1421, 2004.
  • Substrates suitable for use in the CM component employed herein include those which are more prevalently found in cancerous cells and tissue.
  • a CM comprises a substrate for a protease that is more prevalently found in diseased tissue associated with a cancer.
  • the cancer is selected from the group of gastric cancer, breast cancer, osteosarcoma, and esophageal cancer.
  • the cancer is breast cancer.
  • the cancer is a HER2-positive cancer.
  • the cancer is Kaposi sarcoma, hairy cell leukemia, chronic myeloid leukemia (CML), follicular lymphoma, renal cell cancer (RCC), melanoma, neuroblastoma, basal cell carcinoma, cutaneous T-cell lymphoma, nasopharyngeal adenocarcinoma, breast cancer, ovarian cancer, bladder cancer, BCG- resistant non-muscle invasive bladder cancer (NMIBC), endometrial cancer, pancreatic cancer, non-small cell lung cancer (NSCLC), colorectal cancer, esophageal cancer, gallbladder cancer, glioma, head and neck carcinoma, uterine cancer, cervical cancer, or testicular cancer, and the like.
  • CML chronic myeloid leukemia
  • the CM components comprise substrates for protease(s) that is/are more prevalent in tumor tissue.
  • the protease(s) may be produced by a tumor in a subject.
  • Suitable CMs for use herein include any of the protease substrates that are known the art.
  • the CM may comprise a substrate of a serine protease (e.g., u-type plasminogen activator, also known as “uPA” or urokinase), a matriptase (also referred to herein as MT-SP1 or MTSP1).
  • the CM may comprise a substrate of a matrix metalloprotease (MMP).
  • MMP matrix metalloprotease
  • the CM may comprise a substrate of cysteine protease (CP) (e.g., legumain).
  • CP cysteine protease
  • the CM may comprise a substrate for a disintegrin and a metalloproteinase (ADAM) or a disintegrin and a metalloproteinase with a thrombospondin motifs (ADAMTS) (e.g., ADAM8, ADAM9, ADAM10, ADAM12, ADAM15, ADAM17/TACE, 58 CYTX-115-PCT 4862-0152WO1 ADEMDEC1, ADAMTS1, ADAMTS4, ADAMTS5), an aspartate protease (e.g.
  • an aspartic cathepsin e.g., Cathepsin D, Cathepsin E
  • Caspase e.g., Caspase 1, Caspase 2, Caspase 3, Caspase 4, Caspase 5, Caspase 6, Caspase 7, Caspase 8, Caspase 9, Caspase 10, Caspase 14
  • cysteine cathepsin e.g., Cathepsin A, Cathepsin B, Cathepsin C, Cathepsin G, Cathepsin K, Cathepsin L, Cathepsin S, Cathepsin V/L2, Cathepsin X/Z/P
  • a cysteine proteinase e.g., Cruzipain, Legumain, Otubain-2
  • a Chymase DESC1, DPP-4, FAP, an Elastase, FVIIa, FiXA, Fxa, FXIa
  • the protease substrate in the CM may comprise a polypeptide sequence that is not substantially identical (e.g., no more than 90%, 80%, 70%, 60%, or 50% identical) to any polypeptide sequence that is naturally cleaved by the same protease.
  • CM comprises or consists of a sequence selected from SEQ ID NOs: 58- 60, 101-242, 244-282, 318-1354, and 1388-1423.
  • CM comprises PXGL, wherein X is any amino acid.
  • CM comprises GRS, PRS, SRS, or RS.
  • CM comprises a sequence selected from ISSGLLSS (SEQ ID NO: 144), LSGRSNI (SEQ ID NO: 246), DHQSRSGPWGLL (SEQ ID NO: 428), PWGLHQSRS (SEQ ID NO: 649), PWGLSGRS (SEQ ID NO: 805), LSGRSPWGL (SEQ ID NO: 962), or DHQSRS (SEQ ID NO: 1278).
  • CM comprises or consists of an amino acid sequence according to SEQ ID NO: 1388, SEQ ID NO: 1389, SEQ ID NO: 1394, SEQ ID NO: 1399, SEQ ID NO: 1404, SEQ ID NO: 1409, SEQ ID NO: 1414, or SEQ ID NO: 1419.
  • the CM comprises a sequence selected from: SEQ ID NO: 1390, SEQ ID NO: 1391, SEQ ID NO: 1392, SEQ ID NO: 1393, SEQ ID NO: 1395, SEQ ID NO: 1396, SEQ ID NO: 1397, SEQ ID NO: 1398, SEQ ID NO: 1400, SEQ ID NO: 1401, SEQ ID NO: 1402, SEQ ID NO: 1403, SEQ ID NO: 1405, SEQ ID NO: 1406, SEQ ID NO: 1407, SEQ ID NO: 1408, SEQ ID NO: 1410, SEQ ID NO: 1411, SEQ ID NO: 1412, SEQ ID NO: 1413, 59 CYTX-115-PCT 4862-0152WO1 SEQ ID NO: 1415, SEQ ID NO: 1416, SEQ ID NO: 1417, SEQ ID NO: 1418, SEQ ID NO: 1420, SEQ ID NO: 1421, SEQ ID NO: 1422, or SEQ ID NO: 1423.
  • the CMs each independently comprise one of the foregoing sequences.
  • the CM comprises a sequence selected from: SEQ ID NO: 1390, SEQ ID NO: 1391, SEQ ID NO: 1392, or SEQ ID NO: 1393.
  • the CM comprises a sequence selected from: SEQ ID NO: 1395, SEQ ID NO: 1396, SEQ ID NO: 1397, or SEQ ID NO: 1398.
  • the CM comprises a sequence selected from: SEQ ID NO: 1400, SEQ ID NO: 1401, SEQ ID NO: 1402, or SEQ ID NO: 1403.
  • the CM comprises a sequence selected from: SEQ ID NO: 1405, SEQ ID NO: 1406, SEQ ID NO: 1407, or SEQ ID NO: 1408. [00173] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1410, SEQ ID NO: 1411, SEQ ID NO: 1412, or SEQ ID NO: 1413. [00174] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1415, SEQ ID NO: 1416, SEQ ID NO: 1417, or SEQ ID NO: 1418.
  • the CM comprises a sequence selected from: SEQ ID NO: 1420, SEQ ID NO: 1421, SEQ ID NO: 1422, or SEQ ID NO: 1423.
  • the CM comprises a sequence selected from: SEQ ID NO: 1390, SEQ ID NO: 1395, SEQ ID NO: 1400, SEQ ID NO: 1405, SEQ ID NO: 1410, SEQ ID NO: 1415, or SEQ ID NO: 1420.
  • CM comprises or consists of a sequence of SEQ ID NO: 5 or SEQ ID NO: 59.
  • the CM comprises or consists of a sequence of encompassed by the consensus of sequence of any one of SEQ ID NOs: 317–327, 329–335, 340–347, 352–363, 371– 378, 394–401, 410–419, 425–433, 436–449, 453–456, 458–469, 473, 475–482, 485–495 disclosed in WO2015048329, which is incorporated by reference herein in its entirety, and SEQ ID NOs: 1– 162, 268–306 disclosed in WO2015116933, which is incorporated by reference herein in its entirety.
  • the CM comprises or consists of a sequence of any one of SEQ ID NOs: 14–52, 126–154. 159, 315–316, 328, 336–339, 348–351, 364–370, 379–393, 402–409, 420–424, 434–435, 450–452, 457, 470–472, 474, 483, 484 disclosed in WO2015048329, SEQ ID NOs: 163– 60 CYTX-115-PCT 4862-0152WO1 267, 307–384, 402–445, 665–683 disclosed in WO2015116933, SEQ ID NOs: 20–21, 411, 480– 482, 351–369, 18, 71, 370–380, 412–415, 468, 547–554, 319–346 disclosed in WO2016118629, which is incorporated by reference herein in its entirety, and SEQ ID NOs: 1–16, 50–56, 60
  • the CM of a cysteine protease comprises or consists of the sequence of AAN, SAN, or SEQ ID NO: 60.
  • CMs also include those in the sequence listing filed herewith, and those described in WO 2010/081173, WO2021207669, WO2021207657, WO2021142029, WO2021061867, WO2020252349, WO2020252358, WO2020236679, WO2020176672, WO2020118109, WO2020092881, WO2020086665, WO2019213444, WO2019183218, WO2019173771, WO2019165143, WO2019075405, WO2019046652, WO2019018828, WO2019014586, WO2018222949, WO2018165619, WO2018085555, WO2017011580, WO2016179335, WO2016179285, WO2016179257, WO2016149201, WO2024/03
  • the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 1354, SEQ ID NO: 805, SEQ ID NO: 1278, and SEQ ID NO: 144. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 318-1347 and 1388-1423. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 318-331. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 332-400. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 401-794.
  • the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 795-1274. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1275-1347. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1388-1423.
  • CMs that are suitable for use in the AICs described herein, include substrates for Pro-urokinase (e.g., SEQ ID NOs: 101-102), TGF ⁇ (e.g., SEQ ID NO: 103), plasminogen (e.g., SEQ ID NO: 104), Staphylokinase (e.g., SEQ ID NOs: 105-106).
  • the CM comprises or consists of a combination of the example sequences discussed above, a C-terminal truncation variant of the example sequences discussed above, or an 61 CYTX-115-PCT 4862-0152WO1 N-terminal truncation variant of the example sequences discussed above.
  • Truncation variants of the aforementioned amino acid sequences that are suitable for use in a CM are any that retain the recognition site for the corresponding protease. These include C-terminal and/or N-terminal truncation variants comprising at least 3 contiguous amino acids of the above-described amino acid sequences, or at least 4, or at least 5, or at least 6, or at least 7 amino acids of the foregoing amino acid sequences that retain a recognition site for a protease.
  • the truncation variant of the above-described amino acid sequences is an amino acid sequence corresponding to any of the above, but that is C- and/or N-terminally truncated by 1 to about 10 amino acids, 1 to about 9 amino acids, 1 to about 8 amino acids, 1 to about 7 amino acids, 1 to about 6 amino acids, 1 to about 5 amino acids, 1 to about 4 amino acids, or 1 to about 3 amino acids, and which: (1) has at least three amino acid residues; and (2) retains a recognition site for a protease.
  • the truncated CM is an N-terminally truncated CM.
  • the truncated CM is a C-terminally truncated CM. In some aspects, the truncated C is a C- and an N-terminally truncated CM.
  • the CM may comprise a total of 3 amino acids to 25 amino acids. In some aspects, the CM may comprise a total of 3 to 25, 3 to 20, 3 to 15, 3 to 10, 3 to 5, 5 to 25, 5 to 20, 5 to 15, 5 to 10, 10 to 25, 10 to 20, 10 to 15, 15 to 25, 15 to 20, or 20 to 25 amino acids.
  • the CM is specifically cleaved by at least a protease at a rate of about 0.001–1500 ⁇ 10 4 M -1 s -1 or at least 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2.5, 5, 7.5, 10, 15, 20, 25, 50, 75, 100, 125, 150, 200, 250, 500, 750, 1000, 1250, or 1500 ⁇ 10 4 M -1 s -1 .
  • the rate may be measured as substrate cleavage kinetics (k cat /K m ) as disclosed in WO2016118629.
  • the CM comprise a total of about 3 amino acids to about 25 amino acids. In some aspects, the CM comprise a total of about 3 amino acids to about 25 amino acids, about 3 amino acids to about 20 amino acids, about 3 amino acids to about 15 amino acids, about 3 amino acids to about 10 amino acids, about 3 amino acids to about 5 amino acids, about 5 amino acids to about 25 amino acids, about 5 amino acids to about 20 amino acids, about 5 amino acids to about 15 amino acids, about 5 amino acids to about 10 amino acids, about 10 amino acids to about 25 amino acids, about 10 amino acids to about 20 amino acids, about 10 amino acids to about 15 amino acids, about 15 amino acids to about 25 amino acids, about 15 amino acids to about 20 amino acids, or about 20 amino acids to about 25 amino acids.
  • the activatable IL12 fusion protein or AIC comprises multiple CMs that comprise substrates for different proteases.
  • the CM1 and the CM2 in a dimer comprise substrates for different proteases.
  • the CM1 and the CM2 in a dimer comprise substrates for the same protease.
  • Linkers [00184] As described herein, in various aspects the DD and IL12 and/or the IL12 and MM structural elements in the activatable IL12 fusion proteins or AICs are linked via one or more linkers.
  • flexible linker is used herein to refer to a polypeptide that facilitates formation and maintenance of a structure in the activatable IL-12 fusion protein or AIC in circumstances where such structure would otherwise be conformationally constrained, and where inclusion of such flexible linker imparts sufficient flexibility to facilitate the inhibition of binding of a binding partner (e.g., an IL12 receptor) and/or cleavage of a CM by a protease.
  • a binding partner e.g., an IL12 receptor
  • An activatable IL12 fusion protein or AIC may comprise one or more additional components including one or more linkers, and the like.
  • thefirst polypeptide can include a linker disposed between IL12 and the CM.
  • IL12 directly abuts the CM.
  • the DD1 of the first polypeptide, the DD2 of the second polypeptide, or both may be linked to another component, for example, a CM, an MM, or an IL12 subunit (e.g., p35, p40, or both, and when both are present p35 and p40 may be in either order from N-terminus to C-terminus) by a linker.
  • the DD1 and the DD2 comprise an Fc domain.
  • Illustrative Fc hinge domains include, for example, an IgG1 hinge (SEQ ID NO: 73 PKSCDKTHTCPPCPAPELLG and the like), truncated IgG1 hinge (e.g., SEQ ID NO: 1730 DKTHTCPPCPAPELLG and the like), an IgG4 hinge (e.g., SEQ ID NO: 74 63 CYTX-115-PCT 4862-0152WO1 SKYGPPCPPCPAPEFLG; SEQ ID NO: 1731 ESKYGPPCPPCPAPEFLG, and the like), a truncated IgG4 hinge (e.g., SEQ ID NO: 1732 GPPCPPCPAPEFLG, and the like).
  • IgG1 hinge SEQ ID NO: 73 PKSCDKTHTCPPCPAPELLG and the like
  • truncated IgG1 hinge e.g., SEQ ID NO: 1730 DKTHTCPPCPAPELLG and the like
  • the linker has a total length of 1 amino acid to about 15 amino acids.
  • the CM1 and the DD1 directly abut each other in thefirst polypeptide.
  • the CM1 and any linkers disposed between the CM1 and DD1 have a combined total length of 3 to 30, 3 to 25, or 3 to 23, or 3 to 20, or 3 to 18, 3 to 15 amino acids, or 3 to 10 amino acids, or 3 to 7 amino acids.
  • the second polypeptide comprises a linker disposed between the DD2 and the CM2.
  • the DD2 and the CM2 directly abut each other in the second polypeptide.
  • the linker has a total length of 1 amino acid to about 15 amino acids.
  • the linker comprises a sequence of G; GG; or GGGS (SEQ ID NO: 61).
  • the CM2 e.g., any of the cleavable moieties described herein
  • the DD2 e.g., any of the DDs described herein
  • the CM2 and any linkers disposed between the CM2 and DD2 have a combined total length of 3 to 30, 3 to 25, or 3 to 23, or 3 to 20, or 3 to 18, 3 to 15 amino acids, or 3 to 10 amino acids, or 3 to 7 amino acids.
  • one or moreflexible linkers are introduced into the activable IL12 fusion protein or AIC to provideflexibility at one or more of the junctions between domains, between moieties, between moieties and domains, or at any other junctions where a linker would be beneficial.
  • aflexible linker is inserted to facilitate formation and maintenance of a structure in the activable IL12 fusion protein or AIC.
  • linkers described herein can provide the desiredflexibility to facilitate the inhibition of the binding of a binding partner (e.g., an IL12 receptor), or to facilitate cleavage of a CM by a protease.
  • a binding partner e.g., an IL12 receptor
  • linkers are included in the activable IL12 fusion protein or AIC that are all or partiallyflexible, such that the linker can include aflexible linker as well as one or more portions that confer lessflexible structure to provide for a desired activable IL12 fusion protein or AIC three-dimensional structure.
  • Some linkers may include cysteine residues, which may form disulfide bonds and reduceflexibility of the construct.
  • linker length is determined by counting, in a N- to C-terminal direction, the number of amino acids from the N-terminus of the linker adjacent to the C-terminal amino acid of the preceding component, to the C-terminus of the linker adjacent to the N-terminal amino acid of the following component (i.e., where the linker length does not include either the C-terminal amino acid of the preceding component or the N-terminal amino acid of the following component).
  • linker length is determined by counting the number of amino acids from the N-terminus of the linker adjacent to the C-terminal amino acid of the preceding component to C-terminus of the linker adjacent to thefirst cysteine of an Fc hinge region (i.e., where the linker length does not include the C-terminal amino acid of the preceding component or thefirst cysteine of the Fc hinge region).
  • the DD comprises an Fc hinge region that has amino acid residues prior to the first cysteine of the Fc hinge region, that portion of the Fc hinge region is considered a linker and is included in the computation of linker length.
  • a linker includes a total of about 1 amino acid to about 25 amino acids (e.g., about 1 amino acid to about 24 amino acids, about 1 amino acid to about 22 amino acids, about 1 amino acid to about 20 amino acids, about 1 amino acid to about 18 amino acids, about 1 amino acid to about 16 amino acids, about 1 amino acid to about 15 amino acids, about 1 amino acid to about 14 amino acids, about 1 amino acid to about 12 amino acids, about 1 amino acid to about 10 amino acids, about 1 amino acid to about 8 amino acids, about 1 amino acid to about 6 amino acids, about 1 amino acid to about 5 amino acids, about 1 amino acid to about 4 amino acids, about 1 amino acid to about 3 amino acids, about 1 amino acid to about 2 amino acids, about 2 amino acids to about 25 amino acids, about 2 amino acids to about 24 amino acids, about 2 amino acids to about 22 amino acids, about 2 amino acids to about 20 amino acids, about 2 amino acids to about 18 amino acids, about 2 amino acids
  • the linker includes a total of about 1 amino acid, about 2 amino acids, about 3 amino acids, about 4 amino acids, about 5 amino acids, about 6 amino acids, about 7 amino acids, about 8 amino acids, about 9 amino acids, about 10 amino acids, about 11 amino acids, about 12 amino acids, about 13 amino acids, about 14 amino acids, about 15 amino acids, about 16 amino acids, about 17 amino acids, about 18 amino acids, about 19 amino acids, about 20 amino acids, about 21 amino acids, about 22 amino acids, about 23 amino acids, about 24 amino acids, or about 25 amino acids.
  • a linker is rich in glycine (Gly or G) residues.
  • the linker is rich in serine (Ser or S) residues. In some aspects, the linker is rich in glycine and serine residues. In some aspects, the linker has one or more glycine-serine residue pairs (GS) (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more GS pairs). In some aspects, the linker has one or more Gly-Gly-Gly-Ser (GGGS; SEQ ID NO: 61) sequences (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more GGGS sequences).
  • GS glycine-serine residue pairs
  • GGGS Gly-Gly-Gly-Ser
  • the linker has one or more Gly-Gly-Gly-Gly-Ser (GGGGS; SEQ ID NO: 62) sequences (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more GGGGS sequences).
  • the 67 CYTX-115-PCT 4862-0152WO1 linker has one or more Gly-Gly-Ser-Gly (GGSG; SEQ ID NO: 63) sequences (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more GGSG sequences).
  • a linker includes any one of or a combination of one or more of: G, GG, GSSGGSGGSGG (SEQ ID NO: 64), GGGS (SEQ ID NO: 61), GGGSGGGS (SEQ ID NO: 65), GGGSGGGSGGGS (SEQ ID NO: 66), GGGGSGGGGSGGGGS (SEQ ID NO: 67), GGGGSGGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 68), GGGGSGGGGS (SEQ ID NO: 69), GGGGS (SEQ ID NO: 62), GS, GGGGSGS (SEQ ID NO: 70), GGGGSGGGGSGGGGSGS (SEQ ID NO: 71), GGSLDPKGGGGS (SEQ ID NO: 72), PKSCDKTHTCPPCPAPELLG (SEQ ID NO: 73), SKYGPPCPPCPAPEFLG (SEQ ID NO: 74), GKSSGSGSESKS (SEQ ID NO: 75), GST
  • Non-limiting examples of linkers can include a sequence that is at least 70% identical (e.g., at least 72%, at least 74%, at least 75%, at least 76%, at least 78%, at least 80%, at least 82%, at least 84%, at least 85%, at least 86%, at least 88%, at least 90%, at least 92%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical) to GGGS (SEQ ID NO: 61), GSSGGSGGSGG (SEQ ID NO: 64), GGGGSGGGGSGGGGS (SEQ ID NO: 67), GGGGSGS (SEQ ID NO: 70), GGGGSGGGGSGGGGSGS (SEQ ID NO: 71), GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 79), GGSLDPKGGGGS (SEQ ID NO: 72), and GSTSGSGKPGSSEGST (SEQ ID NO: 80).
  • GGGS S
  • the linker includes a sequence selected from the group of: GGSLDPKGGGGS (SEQ ID NO: 72), GGGGSGGGGSGGGGSGS (SEQ ID NO: 71), GGGGSGS (SEQ ID NO: 70), GS, (GS)n, (GGS)n, (GSGGS)n (SEQ ID NO: 81) and (GGGS)n (SEQ ID NO: 61), GGSG (SEQ ID NO: 63), GGSGG (SEQ ID NO: 82), GSGSG (SEQ ID NO: 83), GSGGG (SEQ ID NO: 84), GGGSG (SEQ ID NO: 85), GSSSG (SEQ ID NO: 86), GGGGSGGGGSGGGGS (SEQ ID NO: 67), GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 79), GSTSGSGKPGSSEGST (SEQ ID NO: 226), (GGGGS)n (SEQ ID NO: 216), wherein n is
  • the linker includes a sequence selected from the group consisting of: GGSLDPKGGGGS (SEQ ID NO: 219), GGGGSGGGGSGGGGSGS (SEQ ID NO: 218), GGGGSGS (SEQ ID NO: 217), and GS.
  • the linker includes a sequence selected from the group of: GGGGSGGGGSGGGGS (SEQ ID NO: 213), GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 235), and GSTSGSGKPGSSEGST (SEQ ID 68 CYTX-115-PCT 4862-0152WO1 NO: 80).
  • the linker includes a sequence selected from the group of: GGGGSGGGGSGGGGS (SEQ ID NO: 67) or GGGGS (SEQ ID NO: 62). In some aspects, the linker comprises a sequence of GGGS (SEQ ID NO: 61). In some aspects, the linker comprises a single glycine residue (G), or a sequence of two glycine residues (GG). In some aspects, the linker includes a sequence selected from SEQ ID NOs 61-98.
  • an activable IL12 fusion protein or AIC can include one, two, three, four, five, six, seven, eight, nine, or ten linker sequence(s) (e.g., the same or different linker sequences of any of the exemplary linker sequences described herein or known in the art).
  • a linker comprises sulfo-SIAB, SMPB, and sulfo-SMPB, wherein the linkers react with primary amines sulfhydryls.
  • a MM-DD linking region is the stretch of amino acid residues between the C-terminus of the MM and the amino acid residue that is N-terminally adjacent to the proximal point of interaction between the dimerization domains (i.e., the MM-DD linking region does not include the C-terminal amino acid of the MM or the N- terminal amino acid of the DD that forms the proximal point of interaction to the DD of the corresponding second monomer).
  • the MM- DD linking region is the stretch of amino acid residues between the C-terminus of the MM and the first N-terminal cysteine residue that participates in the disulfide linkage of the Fc (e.g., Cysteine 226 of an IgG1 or IgG4 Fc domain, according to EU numbering).
  • the MM-DD linking region is the stretch of amino acid residues following the C-terminus of the MM until the last amino acid.
  • the MM-DD linking region of the biotin-containing monomer is the stretch of amino acid residues between the C-terminus of the MM and the biotin molecule
  • the MM-DD linking region of the streptavidin-containing monomer is the stretch of amino acid residues between the C-terminus of the MM and the streptavidin molecule.
  • the MM-DD linking region comprises no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids, e.g., 4 to 54, 12 to 21, 17 to 21, or 28 to 54, or 12, 17, 21, 28, or 54 amino acids.
  • the DD is an Fc and the MM-DD linking region is at least 7 amino acids, counting from the first amino acid after Cys226 (Cysteine 226 of an IgG1 or IgG4 Fc domain, 69 CYTX-115-PCT 4862-0152WO1 according to EU numbering) in the N-terminal direction.
  • the DD is an Fc and the MM-DD linking region is 7 to 300 amino acids, 95 to 300 amino acids, 135 to 300 amino acids, 60 to 241 amino acids, or the MM-DD linking region is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101,
  • the DD is an Fc and the IL12-DD linking region (including a flexible linker, or including one or more flexible linkers and one or more CMs, or including one or more flexible linkers, a MM, and one or more CMs) is the stretch of amino acid residues between the C-terminus of the IL12 subunit and the amino acid residue that is N-terminally adjacent to the proximal point of interaction between the dimerization domains (i.e., the IL12-DD linking region does not include the C-terminal amino acid of the IL12 or the N-terminal amino acid of the DD that forms the proximal point of interaction to the DD of the corresponding second monomer).
  • the IL12-DD linking region is the stretch of amino acid residues between the C-terminus of the IL12 and the first N-terminal cysteine residue that participates in the disulfide linkage of the Fc (e.g., Cysteine 226 of an IgG1 or IgG4 Fc domain, according to EU numbering).
  • the IL12-DD linking region is 40 to 300 amino acids, 95 to 300 amino acids, 135 to 300 amino acids, 60 to 241 amino acids, or the IL12-DD linking region is at least 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118
  • the IL12-DD linking region is 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 70 CYTX-115-PCT 4862-0152WO1 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125,
  • a MM-EM linking region is the stretch of amino acid residues between the C-terminus of the MM and the N-terminus of the EM.
  • the MM-EM linking region is the stretch of amino acid residues between the C-terminus of the MM and the first N-terminal residue of the HSA.
  • an activatable IL12 fusion protein or an activatable IL12 construct according to aspects disclosed herein does not include a MM-EM linking region.
  • the C-terminal residue of the MM may be conjugated directly to the N-terminal residue of the EM.
  • the MM-EM linking region is 1 to 300 amino acids, 95 to 300 amino acids, 135 to 300 amino acids, 60 to 241 amino acids, or the linking region is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105,
  • the MM-EM linking region comprises no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acids, or the linking region may be absent (i.e., comprise a direct bond), e.g., 0 to 60, 4 to 54, 12 to 21, 17 to 21, or 28 to 54, or 12, 17, 21, 28, or 54 amino acids.
  • the linking region (flexible linker or flexible linker and CM) between the EM or DD and the p35 subunit of IL12 comprises no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids.
  • the DD is an Fc and the linking region between the DD and the p35 subunit is the stretch of amino acid residues between the C-terminus of the p35 subunit and the amino acid residue that is N- terminally adjacent to the proximal point of interaction between the dimerization domains (i.e., the linking region between the DD and the p35 subunit does not include the C-terminal amino acid of the p35 subunit or the N-terminal amino acid of the DD that forms the proximal point of interaction to the DD of the corresponding second monomer).
  • the linking region between the DD and the p35 subunit is the stretch of amino acid residues between the C-terminus of the p35 subunit and the first N-terminal cysteine residue that participates in the disulfide linkage of the Fc (e.g., Cysteine 226 of an IgG1 or IgG4 Fc domain, according to EU numbering).
  • the linking region (flexible linker or flexible linker and CM) between the EM or DD and the p40 subunit of IL12 comprises no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids.
  • the DD is an Fc and the linking region between the DD and the p40 subunit is the stretch of amino acid residues between the C-terminus of the p40 subunit and the amino acid residue that is N- terminally adjacent to the proximal point of interaction between the dimerization domains (i.e., the linking region between the DD and the p40 subunit does not include the C-terminal amino acid of the p40 subunit or the N-terminal amino acid of the DD that forms the proximal point of interaction to the DD of the corresponding second monomer).
  • the linking region between the DD and the p40 subunit is the stretch of amino acid residues between the C-terminus of the p40 subunit and the first N-terminal cysteine residue that participates in the disulfide linkage of the Fc (e.g., Cysteine 226 of an IgG1 or IgG4 Fc domain, according to EU numbering).
  • the linking region (flexible linker or flexible linker and CM) between the MM and the p35 subunit of IL12 comprises 4 to 60, 12 to 55, 18 to 50, 29 to 43, or no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 72 CYTX-115-PCT 4862-0152WO1 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids.
  • the linking region (flexible linker or flexible linker and CM) between the MM and the p40 subunit of IL12 comprises 4 to 60, 12 to 55, 18 to 50, 29 to 43, or no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids.
  • a linker between the p40 domain and the p35 domain is 7, 8, 9, 10, 11, 12, 13, 14, or 15 amino acids in length, e.g., 7 amino acids or 15 amino acids.
  • the linking region (flexible linker or flexible linker and CM) between the MM and the IL12 is 25 to 47 amino acids in length (including any integer in the range of 25 to 47), e.g., 25, 38, or 47 amino acids.
  • the linking region (flexible linker or flexible linker and CM) between the MM and the DD is 25 to 47 amino acids in length (including any integer in the range of 25 to 47), e.g., 25, 38, or 47 amino acids.
  • the MM comprises a receptor polypeptide of the receptor for the IL12.
  • the receptor polypeptide of the receptor for the IL12 is an extracellular domain (ECD) of the receptor or a portion thereof. Extracellular domains of cytokine receptors have been identified in the literature, for example, in Wang, Xinquan, et al. “Structural biology of shared cytokine receptors.” Annual review of immunology 27 (2009): 29–60.
  • the MM comprises the full length IL12 receptor ECD.
  • the MM is a truncated version of the IL12 receptor ECD.
  • the MM is a concatemer of IL12 receptor polypeptide subsequences.
  • the MM may comprise one or more or two or more subsequences of an amino acid sequence corresponding to a polypeptide that binds to IL12 or a receptor polypeptide of the IL12 receptor, according to the method described, e.g., in WO 2024/216146, which is incorporated by reference in its entirety.
  • the present disclosure includes a CM between two receptor subsequences in a concatemeric MM.
  • the MM is a polypeptide that binds to IL12 but is not a receptor polypeptide or a subsequence of a receptor polypeptide.
  • the MM may be an antibody or antibody fragment (e.g., an antibody variable domain, a Fab fragment, a F(ab’) 2 73 CYTX-115-PCT 4862-0152WO1 fragment, an scFv, a single-chain antibody (scab), a variable domain of camelid-type nanobody (VHH), a domain antibody (dAb), a single domain heavy chain antibody, and a single domain light chain antibody), non-immunoglobulin proteins that mimic antibody binding and/or structure (e.g., anticalins, affilins, affibody molecules, affimers, affitins, alphabodies, avimers, adnectins, DARPins, fynomers, kunitz domain peptides
  • an antibody or antibody fragment e
  • the MM may be a peptide that binds to IL12 and interrupts IL12 binding to its target.
  • the MM is an amino acid sequence of about 200 to about 300 amino acids including any number of amino acids or range of amino acids within about 200 to about 300.
  • the MM is 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 29
  • Methods for screening candidate peptides to obtain MM peptides that selectively and/or specifically bind IL12 can include protein display methods and methods of screening candidate peptides described in, for example, US20200308243A1, WO2009025846A2 and WO2010081173, which are incorporated herein by reference in their entireties.
  • the MM includes a sequence disclosed in US Pat. 11,667,687, US Pat. 11,718,655, and US Pat. 11,634,467, which are incorporated herein by reference in their entireties for all purposes. Exemplary and non-limiting MMs are provided in Table 1 below.
  • the MM comprises an antibody or fragment thereof that binds to and reduces or inhibits one or more activities of IL12, such as, for example, an scFv, a single domain antibody, and the like.
  • the MM comprises an scFv.
  • the scFv binds to and reduces or inhibits one or more activities of the p40 subunit.
  • the scFv binds to and reduces or inhibits one or more activities of the p35 subunit.
  • the activatable IL12 fusion protein or AIC comprises an MM having a HCDR1 sequence comprising SYGMH (SEQ ID NO: 1355), a HCDR2 sequence comprising FIRYDGSNKYYADSVKG (SEQ ID NO: 1356), a HCDR3 sequence comprising HGSHDN 74 CYTX-115-PCT 4862-0152WO1 (SEQ ID NO: 1357), a LCDR1 sequence comprising SGSRSNIGSNTVK (SEQ ID NO: 1358), a LCDR2 sequence comprising YNDQRPS (SEQ ID NO: 1359), and LCDR3 sequence comprising QSYDRYTHPALL (SEQ ID NO: 1360).
  • the activatable IL12 fusion protein or AIC comprises an MM comprising SEQ ID NO: 1361, SEQ ID NO: 1362, or both.
  • the amino acid sequence of the MM comprises a CM.
  • the MM includes an internal linker comprising a CM within the MM sequence.
  • the MM comprising a CM within the MM has a structure comprising: MM’-CM-MM”, wherein “-” comprises a linker or a direct bond.
  • the linker (“-”) is about 2 amino acids to about 6 amino acids.
  • the MM is a concatenated sequence of two or more subsequences joined by a linker comprising a CM
  • MM’ comprises a first peptide
  • MM” comprises a second peptide so that the MM’ and the MM” are linked together by the CM and optionally one or more linkers to develop a single concatenated peptide as a masking moiety (MM).
  • MM’ and MM” do not independently function as masking moieties.
  • the two or more concatenated peptides linked by a linker comprising a CM may be different from each other or identical.
  • MM’ and MM” may be the same sequence or a different sequence.
  • the MM is a concatenated sequence of two or more IL12 receptor polypeptide subsequences that are identical, such that MM’ and MM” comprise the same subsequence, for example, the same IL12 receptor polypeptide subsequence.
  • the MM is a concatenated sequence of two or more polypeptide subsequences that are different.
  • the MM’ may be a subsequence corresponding to an N-terminal portion of the MM sequence and the MM” may be a subsequence corresponding to a C-terminal portion of the MM sequence so that MM’ and MM” are linked together by a CM and optionally one or more linkers to develop a single concatenated peptide as a masking moiety (MM).
  • the MM may comprise a variable light (VL) and variable heavy (VH) chain linked by a linker comprising a CM between the VL and VH chains.
  • the MM’ comprises a variable light (VL) chain and the MM” comprises a variable heavy (VH) chain, or the MM’ comprises the VH and the MM” comprises the VL
  • the MM is an scFv and comprises a CM between the VL and the VH with a structure comprising: VL-CM-VH or VH- CM-VL, wherein “-” comprises a linker or a direct bond.
  • the MM comprises a concatemer of IL 12 receptor polypeptide subsequences capable of binding to IL12 (e.g., a peptide or an extracellular domain (ECD)).
  • MM’ comprises a subsequence corresponding 75 CYTX-115-PCT 4862-0152WO1 to an N-terminal portion of an IL12 receptor amino acid sequence and MM” comprises a subsequence corresponding to a C-terminal portion of the IL12 receptor amino acid sequence so that the N-terminal portion (MM’) and the C-terminal portion (MM”) are linked together by the CM and optionally one or more linkers to develop a single concatenated peptide as a masking moiety (MM).
  • the MM may comprise a structure IL12R’-CM-IL12R”, wherein IL12R’ corresponds to a first stretch of amino acids corresponding to a IL12 receptor polypeptide and IL12R” corresponds to a second stretch of amino acids corresponding to a IL12 receptor polypeptide, and wherein the stretch of amino acids for IL12R’ and IL12R” may be partially overlapping or non-overlapping.
  • the MM is an amino acid sequence of less than 50 amino acids including any number of amino acids or range of amino acids within 1 to 50.
  • the MM is no more than 40 amino acids in length.
  • the MM is no more than 30 amino acids in length.
  • the MM is no more than 20 amino acids in length. In some aspects, the MM is no more than 19, 18, 17, 16, or 15 amino acids in length. In some aspects, the MM is at least 1, 2, 3, 4 amino acids. In some aspects, the MM is 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 amino acids. In some aspects, the MM is 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 29, or 40 amino acids in length. In some aspects, the MM is operably linked to the p40 subunit of IL12, while in other embodiments the MM is operably linked to the p35 subunit of IL12.
  • the MM is linked directly to an IL12 subunit, while in other aspects the MM is linked to an IL12 subunit via a linker, and placed into a functional relationship such that the MM is in a position to bind to the cytokine and inhibit the interaction between IL12 and its binding partner in the body of a subject.
  • Exemplary MMs are listed in Table 1. Table 1.
  • spacer refers to an amino acid residue or amino acid sequence incorporated at a free terminus of the mature activable IL12 fusion protein or AIC.
  • a spacer comprises one or more glutamine (Q) residues.
  • residues in the spacer minimize aminopeptidase and/or exopeptidase action to prevent cleavage of N- terminal amino acids.
  • Illustrative and non-limiting spacer amino acid sequences may comprise or consist of any of the following exemplary amino acid sequences: QGQSGS (SEQ ID NO: 87); GQSGS (SEQ ID NO: 88); QSGS (SEQ ID NO: 89); SGS; GS; S; QGQSGQG (SEQ ID NO: 90); GQSGQG (SEQ ID NO: 91); QSGQG (SEQ ID NO: 92); SGQG (SEQ ID NO: 93); GQG; QG; G; QGQSGQ (SEQ ID NO: 94); GQSGQ (SEQ ID NO: 95); QSGQ (SEQ ID NO: 96); QGQSG (SEQ ID NO: 97); QGQS (SEQ ID NO: 98); SGQ; GQ; and Q.
  • QGQSGS SEQ ID NO: 87
  • GQSGS SEQ ID NO: 88
  • QSGS SEQ ID NO: 89
  • spacer sequences are omitted.
  • This disclosure also provides methods and materials for including additional elements in any of the activatable IL12 fusion proteins or AICs described herein including, for example, a targeting moiety to facilitate delivery to a cell or tissue of interest, an agent (e.g., a therapeutic agent, an antineoplastic agent), a toxin, or a fragment thereof.
  • an agent e.g., a therapeutic agent, an antineoplastic agent
  • a toxin e.g., a fragment thereof.
  • the activatable IL12 fusion protein or AIC is conjugated to a cytotoxic agent, including, without limitation, a toxin (e.g., an enzymatically active toxin of bacterial, fungal, plant, or animal origin, or fragments thereof) or a radioactive isotope.
  • a cytotoxic agent including, without limitation, a toxin (e.g., an enzymatically active toxin of bacterial, fungal, plant, or animal origin, or fragments thereof), or a radioactive isotope.
  • Non-limiting exemplary cytotoxic agents that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: dolastatins and derivatives thereof (e.g., auristatin E, AFP, monomethyl auristatin D (MMAD), monomethyl auristatin F (MMAF), monomethyl auristatin E (MMAE), desmethyl auristatin E (DMAE), auristatin F, desmethyl auristatin F (DMAF), dolastatin 16 (DmJ), dolastatin 16 (Dpv), auristatin derivatives (e.g., auristatin tyramine, auristatin quinolone), maytansinoids (e.g., DM-1, DM-4), maytansinoid derivatives, duocarmycin, alpha-amanitin, turbostatin, phenstatin, hydroxyphenstatin, spongistatin 5, spongistat
  • Non-limiting exemplary enzymatically active toxins that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: diphtheria toxin, exotoxin A chain from Pseudomonas aeruginosa, ricin A chain, abrin A chain, modeccin A chain, alpha- sarcin, Aleuriies fordii proteins, dianfhin proteins, Phytoiaca Americana proteins (e.g., PAPI, PAPII, and PAP-8), momordica charantia inhibitor, curcin, crotirs, sapaonaria officinalis inhibitor, geionin, mitogeliin, restrictocin, phenomycin, neomycin, and tricothecenes.
  • diphtheria toxin exotoxin A chain from Pseudomonas aeruginosa
  • ricin A chain abrin A chain
  • modeccin A chain
  • Non-limiting exemplary anti-neoplastics that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: adriamycin, cerubidine, bleomycin, alkeran, velban, oncovin, fluorouracil, methotrexate, thiotepa, bisantrene, novantrone, thioguanine, procarabizine, and cytarabine.
  • Non-limiting exemplary antivirals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: acyclovir, vira A, and symmetrel.
  • Non-limiting exemplary antifungals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: nystatin.
  • Non-limiting exemplary conjugatable detection reagents that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include:fluorescein and derivatives thereof,fluorescein isothiocyanate (FITC).
  • Non-limiting exemplary antibacterials that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: aminoglycosides, streptomycin, neomycin, kanamycin, amikacin, gentamicin, and tobramycin.
  • Non-limiting exemplary 3beta,16beta,17alpha-trihydroxycholest-5-en-22-one 16-O-(2- O-4-methoxybenzoyl-beta-D-xylopyranosyl)-(1->3)-(2-O-acetyl-alpha-L-arabinopyranoside) (OSW-1) that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: s-nitrobenzyloxycarbonyl derivatives of O6-benzylguanine, topoisomerase inhibitors, hemiasterlin, cephalotaxine, homoharringionine, pyrrol Whyzodiazepine dimers (PBDs), functionalized pyrrolobenzodiazepenes, calcicheamicins, podophyiitoxins, taxanes, and vinca alkoids.
  • PBDs pyrroleauzodiazepine dimers
  • Non-limiting exemplary radiopharmaceuticals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: 123 I , 89 Zr, 125 I, 131 I, 99 mTc, 201 T1, 62 Cu, 18 F, 68 Ga, 13 N, 15 O, 38 K, 82 Rb, 111 In, 133 Xe, 11 C, and 99 mTc (Technetium).
  • Non-limiting exemplary heavy metals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: barium, gold, and platinum.
  • Non-limiting exemplary anti-mycoplasmals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: tylosin, spectinomycin, streptomycin B, ampicillin, sulfanilamide, polymyxin, and chloramphenicol.
  • Conjugation can include any chemical reaction that will bind the two molecules so long as the activatable IL12 fusion protein or AIC and the other moiety retain their respective activities.
  • Conjugation can include many chemical mechanisms, e.g., covalent binding, affinity binding, intercalation, coordinate binding, and complexation.
  • the preferred binding is covalent binding.
  • Covalent binding can be achieved either by direct condensation of existing side chains or by the incorporation of external bridging molecules.
  • Many bivalent or polyvalent linking 90 CYTX-115-PCT 4862-0152WO1 agents are useful in conjugating any of the activatable IL12 fusion proteins or AICs described herein.
  • conjugation can include organic compounds, such as thioesters, carbodiimides, succinimide esters, glutaraldehyde, diazobenzenes, and hexamethylene diamines.
  • the activatable IL12 fusion proteins or AICs can include, or otherwise introduce, one or more non-natural amino acid residues to provide suitable sites for conjugation.
  • an agent and/or conjugate is attached by disulfide bonds (e.g., disulfide bonds on a cysteine molecule) to the antigen-binding domain. Since many cancers naturally release high levels of glutathione, a reducing agent, glutathione present in the cancerous tissue microenvironment can reduce the disulfide bonds, and subsequently release the agent and/or the conjugate at the site of delivery.
  • the conjugate when the conjugate binds to its target in the presence of complement within the target site (e.g., diseased tissue, such as cancerous tissue), the amide or ester bond attaching the conjugate and/or agent to the linker is cleaved, resulting in the release of the conjugate and/or agent in its active form.
  • the conjugates and/or agents when administered to a subject, will accomplish delivery and release of the conjugate and/or the agent at the target site (e.g., diseased tissue, such as cancerous tissue).
  • These conjugates and/or agents are particularly effective for the in vivo delivery of any of the conjugates and/or agents described herein.
  • the linker is not cleavable by enzymes of the complement system.
  • the conjugate and/or agent is released without complement activation since complement activation ultimately lyses the target cell.
  • the conjugate and/or agent is to be delivered to the target cell (e.g., hormones, enzymes, corticosteroids, neurotransmitters, or genes).
  • the linker is mildly susceptible to cleavage by serum proteases, and the conjugate and/or agent is released slowly at the target site.
  • the conjugate and/or agent is designed such that the conjugate and/or agent is delivered to the target site (e.g., disease tissue, such as cancerous tissue) but the conjugate and/or agent is not released.
  • the conjugate and/or agent is attached to the activatable IL12 fusion protein or AIC either directly or via a non-cleavable linker.
  • exemplary non-cleavable linkers include amino acids (e.g., D-amino acids), peptides, or other organic compounds that may be modified to include functional groups that can subsequently be utilized in attachment to the activatable IL12 fusion protein or AIC by methods described herein.
  • the activatable IL12 fusion proteins or AICs include at least one point of conjugation for an agent. In some aspects, all possible points of conjugation are available for conjugation to an agent. In some aspects, the one or more points of conjugation include, without limitation, sulfur atoms involved in disulfide bonds, sulfur atoms involved in interchain disulfide bonds, sulfur atoms involved in interchain sulfide bonds but not sulfur atoms involved in intrachain disulfide bonds, and/or sulfur atoms of cysteine or other amino acid residues containing a sulfur atom.
  • an activatable IL12 fusion protein or AIC is modified to include one or more interchain disulfide bonds.
  • disulfide bonds in the activatable IL12 fusion proteins or AICs can undergo reduction following exposure to a reducing agent such as, without limitation, TCEP, DTT, or ⁇ -mercaptoethanol.
  • a reducing agent such as, without limitation, TCEP, DTT, or ⁇ -mercaptoethanol.
  • the reduction of the disulfide bonds is only partial.
  • partial reduction refers to situations where an activatable IL12 fusion protein or AIC is contacted with a reducing agent and a fraction of all possible sites of conjugation undergo reduction (e.g., not all disulfide bonds are reduced).
  • an activatable IL12 fusion protein or AIC is partially reduced following contact with a reducing agent if less than 99%, (e.g., less than 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10% or less than 5%) of all possible sites of conjugation are reduced.
  • the activatable IL12 fusion protein or AIC having a reduction in one or more interchain disulfide bonds is conjugated to a drug reactive with free thiols.
  • an activatable IL12 fusion protein or AIC is modified so that the therapeutic agents can be conjugated to the activatable IL12 fusion protein or AIC at particular locations on the activatable IL12 fusion protein or AIC.
  • an activatable IL12 fusion protein or AIC can be partially reduced in a manner that facilitates conjugation to the activatable IL12 fusion protein or AIC. In such cases, partial reduction of the activatable IL12 fusion protein or AIC occurs in a manner that conjugation sites in the activatable IL12 fusion protein or AIC are not reduced.
  • the conjugation 92 CYTX-115-PCT 4862-0152WO1 site(s) on the activatable IL12 fusion protein or AIC are selected to facilitate conjugation of an agent at a particular location on the protein construct.
  • Various factors can influence the “level of reduction” of the activatable IL12 fusion protein or AIC upon treatment with a reducing agent.
  • the ratio of reducing agent to an activatable IL12 fusion protein or AIC, length of incubation, incubation temperature, and/or pH of the reducing reaction solution can require optimization in order to achieve partial reduction of the activatable IL12 fusion protein or AIC with the methods and materials described herein.
  • Any appropriate combination of factors e.g., ratio of reducing agent to an activatable IL12 fusion protein or AIC, the length and temperature of incubation with reducing agent, and/or pH of reducing agent
  • An effective ratio of reducing agent to an activatable IL12 fusion protein or AIC can be any ratio that at least partially reduces the activatable IL12 fusion protein or AIC in a manner that allows conjugation to an agent (e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites).
  • the ratio of reducing agent to an activatable IL12 fusion protein or AIC will be in a range from about 20:1 to 1:1, from about 10:1 to 1:1, from about 9:1 to 1:1, from about 8:1 to 1:1, from about 7:1 to 1:1, from about 6:1 to 1:1, from about 5:1 to 1:1, from about 4:1 to 1:1, from about 3:1 to 1:1, from about 2:1 to 1:1, from about 20:1 to 1:1.5, from about 10:1 to 1:1.5, from about 9:1 to 1:1.5, from about 8:1 to 1:1.5, from about 7:1 to 1:1.5, from about 6:1 to 1:1.5, from about 5:1 to 1:1.5, from about 4:1 to 1:1.5, from about 3:1 to 1:1.5, from about 2:1 to 1:1.5, from about 1.5:1 to 1:1.5, or from about 1:1 to 1:1.5.
  • the ratio is in a range of from about 5:1 to 1:1. In some aspects, the ratio is in a range of from about 5:1 to 1.5:1. In some aspects, the ratio is in a range of from about 4:1 to 1:1. In some aspects, the ratio is in a range from about 4:1 to 1.5:1. In some aspects, the ratio is in a range from about 8:1 to about 1:1. In some aspects, the ratio is in a range of from about 2.5:1 to 1:1.
  • An effective incubation time and temperature for treating an activatable IL12 fusion protein or AIC with a reducing agent can be any time and temperature that at least partially reduces the activatable IL12 fusion protein or AIC in a manner that allows conjugation of an agent to an activatable IL12 fusion protein or AIC (e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites).
  • the incubation time and temperature for 93 CYTX-115-PCT 4862-0152WO1 treating an activatable IL12 fusion protein or AIC will be in a range from about 1 hour at 37 °C to about 12 hours at 37 °C (or any subranges therein).
  • An effective pH for a reduction reaction for treating an activatable IL12 fusion protein or AIC with a reducing agent can be any pH that at least partially reduces the activatable IL12 fusion protein or AIC in a manner that allows conjugation of the activatable IL12 fusion protein or AIC to an agent (e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites).
  • an agent e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites.
  • An agent can be modified in a manner to include thiols using a thiol- containing reagent (e.g., cysteine or N-acetyl cysteine).
  • a thiol- containing reagent e.g., cysteine or N-acetyl cysteine.
  • the activatable IL12 fusion protein or AIC can be partially reduced following incubation with reducing agent (e.g., TCEP) for about 1 hour at about 37 °C at a desired ratio of reducing agent to activatable IL12 fusion protein or AIC.
  • reducing agent e.g., TCEP
  • An effective ratio of reducing agent to activatable IL12 fusion protein or AIC can be any ratio that partially reduces at least two interchain disulfide bonds located in the activatable IL12 fusion protein or AIC in a manner that allows conjugation of a thiol-containing agent (e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites).
  • an activatable IL12 fusion protein or AIC is reduced by a reducing agent in a manner that avoids reducing any intrachain disulfide bonds.
  • an activatable IL12 fusion protein or AIC is reduced by a reducing agent in a manner that avoids reducing any intrachain disulfide bonds and reduces at least one interchain disulfide bond.
  • the activatable IL12 fusion protein or AIC can also include an agent conjugated to the activatable IL12 fusion protein or AIC.
  • the conjugated agent is a therapeutic agent.
  • the agent e.g., agent conjugated to an activatable IL12 fusion protein or AIC
  • is a detectable moiety such as, for example, a label or other marker.
  • the agent is or includes a radiolabeled amino acid, one or more biotinyl moieties that can be detected by marked avidin (e.g., streptavidin containing afluorescent marker or enzymatic activity that can be detected by optical or calorimetric methods), one or more radioisotopes or radionuclides, one or morefluorescent labels, one or more enzymatic labels, and/or one or more chemiluminescent agents.
  • detectable moieties are attached by spacer molecules.
  • the agent e.g., cytotoxic agent conjugated to an activatable IL12 fusion protein or AIC
  • the agent is linked to the activatable IL12 fusion protein or AIC using a carbohydrate moiety, sulfhydryl group, amino group, or carboxylate group.
  • the agent e.g., cytotoxic agent conjugated to an activatable IL12 fusion protein or AIC
  • the agent is conjugated to the activatable IL12 fusion protein or AIC via a cleavable conjugation linker and/or a CM (also referred to as a cleavable sequence).
  • the agent e.g., cytotoxic agent conjugated to an activatable IL12 fusion protein or AIC
  • the agent e.g., cytotoxic agent conjugated to an activatable IL12 fusion protein or AIC
  • the linker is a thiol-containing linker.
  • the linker is a non- cleavable linker.
  • an effective conjugation of an agent (e.g., cytotoxic agent) to an activatable IL12 fusion protein or AIC can be accomplished by any chemical reaction that will bind the agent to the activatable IL12 fusion protein or AIC while also allowing the agent and the activatable IL12 fusion protein or AIC to retain functionality.
  • an agent e.g., cytotoxic agent
  • any of the activatable IL12 fusion proteins or AICs conjugated to an agent a variety of bifunctional protein-coupling agents can be used to conjugate the agent to the activatable IL12 fusion protein or AIC including, without limitation, N-succinimidyl-3-(2- pyridyldithiol) propionate (SPDP), iminothiolane (IT), bifunctional derivatives of imidoesters (e.g., dimethyl adipimidate HCL), active esters (e.g., disuccinimidyl suberate), aldehydes (e.g., glutareldehyde), bis-azido compounds (e.g., bis (p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (e.g., bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (e.g., N-succinimidyl
  • a ricin immunotoxin can be prepared as described in Vitetta et al., Science 238: 1098 (1987).
  • a carbon-14-labeled 1-isothiocyanatobenzyl-3-methyldiethylene 95 CYTX-115-PCT 4862-0152WO1 triaminepentaacetic acid (MX-DTPA) chelating agent can be used to conjugate a radionucleotide to the activatable IL12 fusion protein or AIC. (See, e.g., WO94/11026).
  • MX-DTPA 1-isothiocyanatobenzyl-3-methyldiethylene 95 CYTX-115-PCT 4862-0152WO1 triaminepentaacetic acid
  • suitable linkers include: (i) EDC (1-ethyl- 3-(3-dimethylamino-propyl) carbodiimide hydrochloride; (ii) SMPT (4-succinimidyloxycarbonyl- alpha-methyl-alpha-(2-pridyl-dithio)-toluene (Pierce Chem. Co., Cat. (21558G); (iii) SPDP (succinimidyl-6 [3-(2-pyridyldithio) propionamido] hexanoate (Pierce Chem.
  • Sulfo-LC-SPDP sulfosuccinimidyl 6 [3-(2-pyridyldithio)-propianamide] hexanoate
  • sulfo-NHS N-hydroxysulfo-succinimide: Pierce Chem. Co., Cat. #24510 conjugated to EDC.
  • Additional cleavable conjugation linkers include, but are not limited to, SMCC, sulfo-SMCC, SPDB, or sulfo-SPDB.
  • the cleavable conjugation linkers and CMs described above contain components that have different attributes, thus leading to conjugates with differing physio-chemical properties.
  • sulfo-NHS esters of alkyl carboxylates are more stable than sulfo-NHS esters of aromatic carboxylates.
  • NHS-ester containing linkers are less soluble than sulfo-NHS esters.
  • the linker SMPT contains a sterically-hindered disulfide bond, and can form conjugates with increased stability. Disulfide linkages, are in general, less stable than other linkages because the disulfide linkage is cleaved in vitro, resulting in less conjugate available.
  • an agent can be conjugated to the activatable IL12 fusion protein or AIC using a modified amino acid sequence included in the amino acid sequence of the activatable IL12 fusion protein or AIC.
  • the protein construct can be designed for controlled placement and/or dosage of the conjugated agent (e.g., cytotoxic agent).
  • the activatable IL12 fusion protein or AIC can be modified to include a cysteine amino acid residue at positions that provide reactive thiol groups and does not negatively impact 96 CYTX-115-PCT 4862-0152WO1 protein folding and/or assembly and does not alter the target properties.
  • the activatable IL12 fusion protein or AIC can be modified to include one or more non-natural amino acid residues within the amino acid sequence of the activatable IL12 fusion protein or AIC to provide suitable sites for conjugation.
  • the activatable IL12 fusion protein or AIC can be modified to include enzymatically activatable peptide sequences within the amino acid sequence of the activatable IL12 fusion protein or AIC.
  • nucleic acids comprising sequences that encode the activatable IL12 fusion protein or thefirst polypeptide (e.g., any of thefirst polypeptides described herein) and the second polypeptide (e.g., any of the second polypeptides described herein) of any of the activatable IL12 fusion proteins or AICs described herein.
  • a pair of nucleic acids together encode thefirst polypeptide (or the protein portion of thefirst polypeptide) and the second polypeptide (or the protein portion of the second polypeptide).
  • the nucleic acid is a deoxyribonucleic acid (DNA).
  • the nucleic acid is a ribonucleic acid (RNA).
  • RNA ribonucleic acid
  • the polynucleotide sequence of the nucleic acid may be codon optimized for optimal expression from the desired host cell species.
  • Vectors [00253] Provided herein are vectors and sets of vectors including any of the nucleic acids described herein. One skilled in the art will be capable of selecting suitable vectors or sets of vectors (e.g., expression vectors) for making any of the activatable IL12 fusion proteins or AICs described herein, and using the vectors or sets of vectors to express any of the activatable IL12 fusion proteins or AICs described herein.
  • vector refers to a polynucleotide capable of inducing the expression of a recombinant protein (e.g., afirst or second polypeptide) in a cell (e.g., any of the cells described herein).
  • a “vector” is able to deliver nucleic acids and fragments thereof into a host cell, and includes regulatory sequences (e.g., promoter, enhancer, poly(A) signal). Exogenous 97 CYTX-115-PCT 4862-0152WO1 polynucleotides may be inserted into the expression vector in order to be expressed.
  • the term “vector” also includes artificial chromosomes, plasmids, retroviruses, and baculovirus Vectors. [00255] Methods for constructing suitable vectors that include any of the nucleic acids described herein, and suitable for transforming cells (e.g., mammalian cells) are well-known in the art.
  • Non-limiting examples of vectors include plasmids, transposons, cosmids, and viral vectors (e.g., any adenoviral vectors (e.g., pSV or pCMV vectors), adeno-associated virus (AAV) vectors, lentivirus vectors, and retroviral vectors), and any Gateway® vectors.
  • adenoviral vectors e.g., pSV or pCMV vectors
  • AAV adeno-associated virus
  • lentivirus vectors lentivirus vectors
  • retroviral vectors e.g., any Gateway® vectors.
  • the vector is an expression vector.
  • a pair of vectors together include a pair of nucleic acids that together encode thefirst polypeptide and the second polypeptide of any of the AICs described herein.
  • the pair of vectors is a pair of expression vectors.
  • Cells [00260] Also provided herein are recombinant host cells that comprise any of the nucleic acids, vector or sets of vectors described herein that encode an activatable IL12 fusion protein or an AIC. As used herein, the term “recombinant host cell” refers to a cell into which an exogenous polynucleotide has been introduced.
  • the exogenous polynucleotide is an expression vector.
  • a prokaryotic host cell is a genetically modified prokaryotic host cell (e.g., a bacterium), by virtue of introduction into a suitable prokaryotic host cell of a heterologous nucleic acid, e.g., an exogenous nucleic acid that is foreign to (not found in nature 98 CYTX-115-PCT 4862-0152WO1 in) the prokaryotic host cell, or a recombinant nucleic acid that is not normally found in the prokaryotic host cell; and a subject eukaryotic host cell is a genetically modified eukaryotic host cell, by virtue of introduction into a suitable eukaryotic host cell of a heterologous nucleic acid, e.g., an exogenous nucleic acid that is foreign to the eukaryotic host cell, or a recombinant nucleic acid that is not naturally found in the
  • Suitable methods of introducing any of the nucleic acids and/or vectors (e.g., any of the vectors or any of the sets of vectors described herein) described herein into a cell include any method that is known in the art.
  • Non-limiting examples of methods that can be used to introducing a nucleic acid into a cell include: lipofection, calcium phosphate transfection, cationic polymer transfection, viral transduction (e.g., adenoviral transduction, lentiviral transduction), nanoparticle transfection, and electroporation.
  • the introducing step includes introducing into a cell a vector or vectors (e.g., any of the vectors or sets of vectors described herein) that comprise(s) a nucleic acid encoding the polypeptide(s) that make up any of the activatable IL12 fusion proteins or AICs described herein.
  • the activatable IL12 fusion proteins or AICs can be produced by any cell, including a prokaryotic cell (e.g., a bacterial cell) or a eukaryotic cell.
  • eukaryotic cell refers to a cell having a distinct, membrane- bound nucleus.
  • Such cells include, for example, a mammalian cell, an insect cell, a fungal cell, a plant cell, and the like.
  • the eukaryotic cell is a yeast cell, such as Saccharomyces cerevisiae.
  • the eukaryotic cell is a higher eukaryote, such as a mammalian cell, an avian cell, a plant cell, an insect cell, and the like.
  • Non-limiting examples of mammalian cells include a rodent cell (e.g., a mouse cell, a rat cell, a hamster cell, such as a Chinese hamster ovary (CHO) cell, a non-human primate cell, a human cell, such as a human embryonic kidney cell(e.g., HEK293 cells), and the like.
  • the cell is a prokaryotic cell.
  • Exemplary prokaryotic cells include, for example, an E. coli cell, a Bacillus sp. cell, and the like.
  • Methods of Producing Activatable IL12 Fusion Proteins or Constructs include: (a) culturing any of the recombinant host cells described herein in a liquid culture medium under conditions sufficient to produce the activatable IL12 fusion protein or AIC; and (b) recovering the activatable IL12 fusion protein or AIC from the host cell and/or the liquid culture medium.
  • Methods of culturing cells are well known in the art. Cells can be maintained in vitro under conditions that favor cell proliferation, cell differentiation, and cell growth.
  • cells can be cultured by contacting a cell (e.g., any of the cells described herein) with a cell culture medium that includes the necessary growth factors and supplements sufficient to support cell viability and growth.
  • the method further includes isolating the recovered activatable IL12 fusion proteins or AIC.
  • methods of isolation include: ammonium sulfate precipitation, polyethylene glycol precipitation, size exclusion chromatography, ligand-affinity chromatography, ion-exchange chromatography (e.g., anion or cation), and hydrophobic interaction chromatography.
  • compositions and methods described herein may involve use of non-reducing or partially-reducing conditions that allow disulfide bonds to form between the dimerization domains to form and maintain dimerization of the AICs.
  • the method further includes formulating the activatable IL12 fusion proteins or AICs into a pharmaceutical composition.
  • formulations are known in the art and are described herein.
  • any of the activatable IL12 fusion proteins or AICs described herein can be formulated for any route of administration (e.g., intravenous, intratumoral, subcutaneous, intradermal, oral (e.g., inhalation), transdermal (e.g., topical), transmucosal, or intramuscular).
  • routes of administration e.g., intravenous, intratumoral, subcutaneous, intradermal, oral (e.g., inhalation), transdermal (e.g., topical), transmucosal, or intramuscular.
  • activatable IL12 fusion proteins or AICs produced by any of the methods described herein.
  • compositions e.g., pharmaceutical compositions
  • kits that include at least one dose of any of the compositions (e.g., pharmaceutical compositions) described herein.
  • the activatable IL12 fusion proteins or AICs disclosed herein include IL12 mutants.
  • mutants can be used that have advantageous properties compared to the wild type IL12, e.g., exhibit less aggregation compared to wild type IL12 or control activatable IL12 fusion protein or AIC that does not comprise the mutated IL12.
  • the present disclosure provides a method of producing an ACC comprising: culturing a cell comprising a polynucleotide encoding an activatable IL12 fusion protein or AIC herein in a liquid culture medium under conditions sufficient to produce the activatable IL12 fusion protein or AIC; purifying the activatable IL12 fusion protein or AIC using an affinity chromatography, wherein the purified polypeptide has a purity of at least about 40%; and recovering the activatable IL12 fusion protein or AIC from the cell or the liquid culture medium.
  • the purified polypeptide has a purity of at least 50%, 60%, 70%, 75%, 80%, 85%, 90%, or 95%.
  • the polypeptides are subjected to a Protein A affinity chromatography step, followed by preparative size exclusion chromatography (SEC) to prepare purified activatable IL12 fusion proteins.
  • SEC preparative size exclusion chromatography
  • the activatable IL12 fusion proteins are purified to 95% or more monomer as measured by analytical SEC.
  • the disclosures of US11,655,277, WO2023/050006, US Pat. 11,358,999, US Pat. 7,910,564, US Pat. 7,872,107, US Pat.7,833,754, US Pat.11,345,732, WO2017062953A1, US Pat.11,787,864 are incorporated herein by reference in their entireties for all purposes.
  • a disease e.g., a cancer (e.g., any of the cancers described herein)
  • a subject including administering a therapeutically effective amount of any of the activatable IL12 fusion proteins or AICs described herein to the subject.
  • the disorder being treated is a cancer.
  • the disorder being treated is an autoimmune disorder.
  • the disorder being treated is an inflammatory disorder.
  • subject refers to any mammal.
  • the subject is a feline (e.g., a cat), a canine (e.g., a dog), an equine (e.g., a horse), a rabbit, a pig, a rodent (e.g., a mouse, a rat, a hamster or a guinea pig), a non-human primate (e.g., a simian (e.g., a monkey (e.g., a baboon, a marmoset), or an ape (e.g., a chimpanzee, a gorilla, an orangutan, or a gibbon)), or a human.
  • a feline e.g., a cat
  • a canine e.g., a dog
  • an equine e.g., a horse
  • a rabbit e.g., a pig
  • a rodent e.g., a
  • the subject is a human. 101 CYTX-115-PCT 4862-0152WO1 [00275] In some aspects, the subject has been previously identified or diagnosed as having the disease (e.g., cancer, including, for example, any of the cancers described herein). [00276] As used herein, “treat” includes reducing the severity, frequency or the number of one or more (e.g., 1, 2, 3, 4, or 5) symptoms or signs of a disease (e.g., a cancer (e.g., any of the cancers described herein)) in the subject (e.g., any of the subjects described herein).
  • a cancer e.g., any of the cancers described herein
  • the disease is cancer
  • treating results in reducing cancer growth, inhibiting cancer progression, inhibiting cancer metastasis, or reducing the risk of cancer recurrence in a subject having cancer.
  • the disease is a cancer.
  • methods of treating a subject in need thereof e.g., any of the exemplary subjects described herein or known in the art
  • administering e.g., administering to the subject a therapeutically effective amount of any of the activatable IL12 fusion proteins or AICs described herein or any of the compositions (e.g., pharmaceutical compositions) described herein.
  • the subject has been identified or diagnosed as having a cancer.
  • Non-limiting examples of cancer include: solid tumor, hematological tumor, sarcoma, osteosarcoma, glioblastoma, neuroblastoma, melanoma, rhabdomyosarcoma, Ewing sarcoma, osteosarcoma, B-cell neoplasms, multiple myeloma, a lymphoma (e.g., B-cell lymphoma, B-cell non-Hodgkin’s lymphoma, Hodgkin’s lymphoma, cutaneous T-cell lymphoma), a leukemia (e.g., hairy cell leukemia, chronic lymphocytic leukemia (CLL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), acute lymphocytic leukemia (ALL)), myelodysplastic syndromes (MDS), Kaposi sarcoma, retinoblastoma, stomach cancer, urothelial carcinoma,
  • the cancer is a lymphoma.
  • the lymphoma is Burkitt’s lymphoma.
  • the subject has been identified or diagnosed as having familial cancer syndromes such as Li Fraumeni Syndrome, Familial Breast- Ovarian Cancer (BRCA1 or BRAC2 mutations) Syndromes, and others.
  • familial cancer syndromes such as Li Fraumeni Syndrome, Familial Breast- Ovarian Cancer (BRCA1 or BRAC2 mutations) Syndromes, and others.
  • BRCA1 or BRAC2 mutations Familial Breast- Ovarian Cancer
  • the disclosed methods are also useful in treating non-solid cancers.
  • Exemplary solid tumors include malignancies (e.g., sarcomas, adenocarcinomas, and carcinomas) of the various organ systems, such as those of lung, breast, lymphoid, gastrointestinal (e.g., colon), and genitourinary (e.g., renal, urothelial, or 102 CYTX-115-PCT 4862-0152WO1 testicular tumors) tracts, pharynx, prostate, and ovary.
  • Exemplary adenocarcinomas include colorectal cancers, renal-cell carcinoma, liver cancer, non-small cell carcinoma of the lung, and cancer of the small intestine.
  • Exemplary cancers described by the National Cancer Institute include: Acute Lymphoblastic Leukemia, Adult; Acute Lymphoblastic Leukemia, Childhood; Acute Myeloid Leukemia, Adult; Adrenocortical Carcinoma; Adrenocortical Carcinoma, Childhood; AIDS- Related Lymphoma; AIDS-Related Malignancies; Anal Cancer; Astrocytoma, Childhood Cerebellar; Astrocytoma, Childhood Cerebral; Bile Duct Cancer, Extrahepatic; Bladder Cancer; Bladder Cancer, Childhood; Bone Cancer, Osteosarcoma/Malignant Fibrous Histiocytoma; Brain Stem Glioma, Childhood; Brain Tumor, Adult; Brain Tumor, Brain Stem Glioma, Childhood; Brain Tumor, Cerebellar Astrocytoma, Childhood; Brain Tumor, Cerebral Astrocytoma/Malignant Glioma, Childhood; Brain Tumor, Ependym
  • exemplary cancers include diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL).
  • DLBCL diffuse large B-cell lymphoma
  • MCL mantle cell lymphoma
  • Metastases of the aforementioned cancers can also be treated or prevented in accordance with the methods described herein.
  • these methods can result in a reduction in the number, severity, or frequency of one or more symptoms of the cancer in the subject (e.g., as compared to the number, severity, or frequency of the one or more symptoms of the cancer in the subject prior to treatment).
  • the methods further include administering to a subject an additional therapeutic agent (e.g., one or more of the therapeutic agents listed in Table 2). Table 2.
  • Antibody Trade Name (antibody name) Target 105 CYTX-115-PCT 4862-0152WO1 BexxarTM (tositumomab) CD20 Gaz vaTM (obinutuzumab) CD20 106 CYTX-115-PCT 4862-0152WO1 (depatuxizumab mafodotin) EGFR (futuximab:modotuximab) EGFR 107 CYTX-115-PCT 4862-0152WO1 (teprotumumab) IGF1R SimulectTM (basiliximab) IL2R ) 108 CYTX-115-PCT 4862-0152WO1 CBT-501 (genolimzumab PD1 ABBV181 (budi alimab) PD1 109 CYTX-115-PCT 4862-0152WO1 EnbrelTM (etanercept) TNF-R (ma atumumab)
  • the composition comprises water and an activatable IL12 fusion protein or AIC of the present invention.
  • the composition comprises water and any of the nucleic acids of the present disclosure.
  • Such compositions are useful for transfecting cells.
  • pharmaceutical compositions that comprise any of the activatable IL12 fusion proteins or AICs described herein and one or more (e.g., 1, 2, 3, 4, or 5) pharmaceutically acceptable carriers (e.g., any of the pharmaceutically acceptable carriers described herein), diluents, or excipients.
  • the compositions e.g.
  • compositions that include any of the activatable IL12 fusion proteins or AICs described herein can be disposed in a sterile vial or a pre-loaded syringe.
  • the compositions e.g. pharmaceutical compositions
  • the compositions can be formulated for different routes of administration (e.g., intravenous, subcutaneous, intramuscular, intraperitoneal, or intratumoral).
  • any of the pharmaceutical compositions described herein can include one or more buffers (e.g., a neutral-buffered saline, a phosphate-buffered saline (PBS), amino acids (e.g., glycine), one or more carbohydrates (e.g., glucose, mannose, sucrose, dextran, or mannitol), one or more antioxidants, one or more chelating agents (e.g., EDTA or glutathione), one or more preservatives, and/or a pharmaceutically acceptable carrier (e.g., bacteriostatic water, PBS, or saline).
  • buffers e.g., a neutral-buffered saline, a phosphate-buffered saline (PBS)
  • amino acids e.g., glycine
  • carbohydrates e.g., glucose, mannose, sucrose, dextran, or mannitol
  • antioxidants e.g., one or more antioxidants
  • the phrase “pharmaceutically acceptable carrier” refers to any and all solvents, dispersion media, coatings, antibacterial agents, antimicrobial agents, isotonic and 110 CYTX-115-PCT 4862-0152WO1 absorption delaying agents, and the like, compatible with pharmaceutical administration.
  • Suitable carriers include, but are not limited to: water, saline, ringer’s solutions, dextrose solution, and about 5% human serum albumin.
  • any of the activatable IL12 fusion proteins or AICs described herein are prepared with carriers that protect against rapid elimination from the body, e.g., sustained and controlled release formulations, including implants and microencapsulated delivery systems.
  • Biodegradable, biocompatible polymers can be used, e.g., ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Methods for preparation of such pharmaceutical compositions and formulations are apparent to those skilled in the art.
  • the present disclosure also provides a composition (e.g., a composition produced during the process of making the activatable IL12 fusion protein or AIC), in which the purified activatable IL12 fusion protein or AIC is at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, or 95% pure.
  • kits that include any of the activatable IL12 fusion proteins or AICs described herein, any of the compositions that include any of the activatable IL12 fusion proteins or AICs described herein, or any of the pharmaceutical compositions that include any of the activatable IL12 fusion proteins or AICs described herein.
  • kits that include one or more second therapeutic agent(s) selected from Table 2 in addition to activatable IL12 fusion proteins or AICs described herein.
  • the second therapeutic agent(s) may be provided in a dosage administration form that is separate from the activatable IL12 fusion proteins or AICs.
  • the second therapeutic agent(s) may be formulated together with the activatable IL12 fusion proteins or AICs.
  • the kit comprises (1) an activatable IL12 fusion protein or AIC comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 1–54, and (2) a second therapeutic agent selected from Table 2.
  • kits described herein can include instructions for using any of the compositions (e.g., pharmaceutical compositions) and/or any of the activatable IL12 fusion proteins or AICs described herein.
  • the kits can include instructions for performing any of the methods described herein.
  • the kits can include at least one dose of any of the compositions (e.g., pharmaceutical compositions) described herein.
  • the kits can provide a syringe for administering any of the pharmaceutical compositions described herein.
  • Example 1 Production of Activatable IL12 Fusion Proteins and Constructs [00294] Activatable IL12 fusion proteins and AICs containing human IL12 (FIGs. 1A–1K) were prepared by recombinant methods.
  • polypeptides were prepared by transforming a host cell with a polynucleotide encoding the sequences of SEQ ID NOs: 1–54 and 1532, 1533, 1536, 1537, 1540, 1541, 1544, 1545, 1548, 1550, 1552, 1553, 1556, 1557, 1560, 1561, 1564, 1565, 1568, 1569, 1572, 1573, 1576, 1577, 1580, 1581, 1584, 1585, 1588, 1590, 1592, 1593, 1596, 1597, 1600, 1601, 1604, 1605, 1608, 1609, 1612, 1613, 1616, 1617, 1620, 1621, 1624, 1625, 1628, 1629, 1632, and 1633.
  • Supernatant harvested from recombinant host cells expressing the polypeptides may be subjected to a Protein A affinity chromatography step, followed by preparative size exclusion chromatography (SEC) to prepare purified activatable IL12 fusion proteins.
  • SEC preparative size exclusion chromatography
  • the purified products can be confirmed to be about 95% or more monomer by analytical SEC.
  • Table 6 provides a description of illustrative AICs. Table 6.
  • Example 3 In vitro evaluation of IL12 activity in reporter assay [00296] The activities of activatable IL12 constructs were tested in vitro using IL12 responsive HEK293 cells. The IL12-responsive HEK293 cells were generated by stable transfection with the human IL12Rb1 and IL12Rb2 genes, along with the genes of the IL12 signaling pathway.
  • the cells also feature an STAT4-inducible secreted embryonic alkaline phosphatase (SEAP) reporter gene.
  • SEAP embryonic alkaline phosphatase
  • DMEM GlutaMax TM media supplemented with 10% FBS, Pen/Strep, 10 ⁇ g/mL Puromycin, and 100 ⁇ g/mL of Normocin TM .
  • the addition of IL12 to these cells activates the STAT4 and subsequently induces the production of SEAP which can be readily assessed in the supernatant using QUANTI-Blue solution, a colorimetric detection for alkaline phosphatase activity.
  • IL12-responsive HEK293 cells were prepared at a concentration of 10 6 cells/mL in DMEM media supplemented with 10% FBS and 50 ⁇ L aliquots were pipetted into wells of a white flat-bottom 96-well plate (50,000 cells/well). The tested constructs were diluted in DMEM media supplemented with 10% FBS. Duplicate of three-fold serial dilutions were prepared from which 50 ⁇ L was added to each well. After 20–24 hours of incubation at 37°C, 20 ⁇ L of supernatant of the induced reporter cells was transferred to wells of aflat-bottom 96-well plate. 180 ⁇ L of resuspended QUANTI-Blue solution was added per well.
  • FIGs.6–9 show IL12 activity of constructs SEQ ID NOs.: 7 to 52 and SEQ ID NO: 1662 and 1663 (ProC670/ProC671) in HEK-Blue IL12 reporter assay. EC50 values are summarized in Table 3.
  • ProC1910, ProC1911, ProC1912, ProC1913, ProC1914, and ProC1915 was reduced 2.5- to 6-fold compared to unmasked counterpart ProC670 ( Figure 1F).
  • the activity of ProC1977, ProC1978, ProC1979, ProC1980, ProC1981, ProC1982, ProC2695, ProC2696, 117 CYTX-115-PCT 4862-0152WO1 ProC2697, ProC2698, ProC2699, ProC2700, ProC2701, ProC2702, ProC2703, ProC2704, and ProC2705 was 1- to 4-fold reduced compared to unmasked counterpart ProC671 (Figure 1G).
  • Table 3 Table 3.
  • EC50 HEK-Blue Reporter Assay rhIL12 ProC670 ProC1910 ProC1911 ProC1912 ProC1913 ProC1914 ProC1915 EC50 5379 259 1446 7256 8274 1301 7692 9923 00
  • Example 4 In vitro characterization of exemplary IL12 constructs [00299] In one reporter assay, the activities of certain IL12 constructs ProC2020, ProC1726, and ProC1727 were evaluated before and after activation with protease (FIG. 10).
  • the activity of ProC2020 was reduced at least 250-fold as compared to recombinant human IL12 (rhIL12) (PeproTech, Catalog #200-12H), and at least 150-fold as compared to the activated ProC2020.
  • the activity of ProC1726 was reduced at least 150-fold as compared to rhIL12 and at least 50-fold as compared to the activated ProC1726.
  • the activity of ProC1727 was reduced at least 40-fold as compared to rhIL12 and at least 15-fold as compared to the activated ProC1727.
  • EC50 values for rhIL12, ProC2020, ProC1726, ProC1727, ProC2020+MMP14, ProC1726+MMP14, ProC1727+MMP14 are provided below in Table 4.
  • the activities of certain IL12 constructs ProC5145, ProC5146, ProC5147, ProC5148, ProC5150, ProC5152, ProC5153, ProC5333, ProC5334, ProC5584, ProC5585, ProC5586, ProC5587, ProC5745, ProC5746, ProC5747 and ProC5748 were evaluated before and after activation with protease (FIGs.18–24).
  • ALT and AST levels were also assessed as measures of toxicity on day 12 (FIG. 28).
  • Sequences for exemplary Activatable IL12 fusion proteins and AICs are shown in Table 7, below.
  • the Italicized text corresponds to IL12 p40 and p35
  • the bold text corresponds to Brikianumab VL and VH
  • the underlined text corresponds to substrate
  • the italic and bold text corresponds to the IL12RB2 ECD fragment.
  • An activatable interleukin 12 (IL12) fusion protein comprising afirst polypeptide having a structure selected from: i) N'-DD-L1-MM-L2-IL12-C', ii) C'-DD-L1-MM-L2-IL12-N', iii) N'-DD-L1-IL12-L2-MM-C', or iv) C'-DD-L1-IL12-L2-MM-N', wherein: a) L1 is afirst linker or is absent; b) L2 is a second linker; c) DD is a dimerization domain; d) MM is a masking moiety; e) IL12 comprises an IL12 ⁇ (p35) domain and an IL12 ⁇ (p40) domain; f) N' is an amino terminus of the activatable IL12
  • Aspect 2 The activatable IL12 fusion protein of aspect 1, wherein the activatable IL12 fusion protein has 1.5-fold to about 1000-fold, or about 2-fold to about 100-fold, or about 100-fold to about 1000-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay.
  • Aspect 3 The activatable IL12 fusion protein of aspect 1 or 2, wherein the fusion protein comprises a second polypeptide comprising a second dimerization domain (DD2), and wherein the DD and the DD2 are dimerized.
  • DD2 dimerization domain
  • Aspect 5 The activatable IL12 fusion protein of any one of the preceding aspects, wherein the L2 comprises a CM, and the L1 is absent or the L1 does not comprise a CM.
  • Aspect. A The activatable IL12 fusion protein of any of the aspects disclosed herein, wherein L1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. [00312] Aspect. B.
  • Aspect C The activatable IL12 fusion protein of any one of aspects 3 to 4, having a structure comprising: i) C'-DD1-L1-MM-CM-IL12-N', and DD2; or ii) N'-DD1-L1-MM-CM-IL12-C', and DD2.
  • Aspect D Aspect D.
  • CM1 a first cleavable moiety
  • CM2 a second cleavable moiety
  • Aspect E The activatable IL12 fusion protein of aspect D, having a structure comprising: 299 CYTX-115-PCT 4862-0152WO1 i) C'-DD1-CM1-IL12-CM2-MM-N', and DD2; ii) N'-DD1-CM1-IL12-CM2-MM-C', and DD2; iii) C'-DD1-CM1-MM-CM2-IL12-N', and DD2; or vi) N'-DD1-CM1-MM-CM2-IL12-C', and DD2.
  • Aspect F The activatable IL12 fusion protein of aspect D, further comprising a third cleavable moiety (CM3).
  • Aspect G The activatable IL12 fusion protein of aspect F, having a structure comprising: i) C'-DD1-CM1-MM-CM2-IL12-N', and DD2; or ii) N'-DD1-CM1-MM-CM2-IL12-C', and DD2, wherein the MM comprises a first sequence (MM’) and a second sequence (MM”), and wherein the MM further comprises the CM3 within the MM sequence according to the structure comprising: MM’-CM3-MM”.
  • Aspect H Aspect H.
  • the activatable IL12 fusion protein of aspect 3 or aspect 4 comprising afirst polypeptide having a structure N'-DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2- IL12-N', and a second polypeptide having a N'-DD2-L3-MM2-L4-IL12-C' or C'-DD2-L3-MM2- L4-IL12-N', wherein MM1 is a first masking moiety, MM2 is a second masking moiety, L3 is a third linker, and L4 is a fourth linker. [00319] Aspect I.
  • the activatable IL12 fusion protein of aspect H wherein L1 and L3 comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • Aspect J The activatable IL12 fusion protein of aspect H or aspect I, wherein L2 and L4 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 300 CYTX-115-PCT 4862-0152WO1 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids.
  • Aspect K Aspect K.
  • CM1 a first cleavable moiety
  • CM2 a second cleavable moiety
  • CM3 a third cleavable moiety
  • CM4 a fourth cleavable moiety
  • CM4 a structure comprising: i) C'-DD1-CM1-MM1-CM2-IL12-N', and C'-DD2-CM3-MM2-CM4-IL12-N'; or ii) N'-DD1-CM1-MM1-CM2-IL12-C', and N'-DD2-CM3-MM2-CM4-IL12-C'.
  • activatable IL12 fusion protein of aspect 3 or aspect 4 comprising a first polypeptide having a structure N'-DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2-IL12- N'; and a second polypeptide having a structure N'-DD2-L3-MM2-C' or C'-DD2-L3-MM2-N', wherein MM1 is a first masking moiety, MM2 is a second masking moiety, and L3 is a third linker, wherein the MM1 comprises a first sequence (MM1’) and a second sequence (MM1”), and wherein the MM1 further comprises a second cleavable moiety (CM2) within the MM1 according to the structure comprising: MM1’-CM2-MM1”.
  • Aspect M The activatable IL12 fusion protein of aspect L, wherein L1 and L3 comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • Aspect N The activatable IL12 fusion protein of aspect L or aspect M, wherein L2 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids.
  • Aspect O Aspect O.
  • CM is a first cleavable moiety (CM1) and further comprising a second cleavable moiety (CM2), a third cleavable moiety (CM3), and a fourth cleavable moiety (CM4), and having a structure comprising: i) C'-DD1-CM1-MM1-CM2-IL12-N', and C’DD2-CM3-MM2-N’; or 301 CYTX-115-PCT 4862-0152WO1 ii) N'-DD1-CM1-MM1-CM2-IL12-C', and N’-DD2-CM3-MM2-N’ wherein the MM1 comprises a first sequence (MM1’) and a second sequence (MM1”), and wherein the MM1 further comprises the CM4 within the MM1 according to the structure comprising: MM1’-CM4-MM1”.
  • Aspect 6 The activatable IL12 fusion protein of any one of the preceding aspects, wherein at least one of the L1 and the L2 comprises a CM that is a substrate for a matrix metalloprotease (MMP) or a serine protease, or both.
  • MMP matrix metalloprotease
  • Aspect 7 The activatable IL12 fusion protein of aspect 6, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14.
  • Aspect 9 The activatable IL12 fusion protein of any one of the preceding aspects, wherein the MM is a Fab fragment or the MM is an scFv.
  • Aspect 10 The activatable IL12 fusion protein of any one of aspects 3 to 9, wherein the DD and the DD2 are covalently bound to each other via at least one disulfide bond thereby forming a dimer. [00331] Aspect 11.
  • Aspect 12 The activatable IL12 fusion protein of any one of the preceding aspects, wherein the DD is more proximal to the p35 domain than to the p40 domain.
  • Aspect 13 The activatable IL12 fusion protein of any one of the preceding aspects, wherein the DD is at the amino terminal end of thefirst polypeptide, and IL12 is at the carboxy terminal end of thefirst polypeptide.
  • Aspect 15 The activatable IL12 fusion protein of any one of aspects 1 to 12, wherein the L2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 58 to 98, 101 to 282, 318-1354, and 1388-1423 including any combination thereof. 302 CYTX-115-PCT 4862-0152WO1 [00336] Aspect 16.
  • the activatable IL12 fusion protein of any one of the preceding aspects wherein the MM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 283 to 287, and 290 to 306, 1355 to 1362, 1426-1433, or a combination thereof, e.g., in some aspects, the MM comprises CDRs comprising SEQ ID NOs: 1355-1360, or in some aspects, the MM comprises SEQ ID NOs: 1361, 1362, or both, and in some aspects, SEQ ID NOs: 1361 and 1362 are connected by a linker. [00338] Aspect 18. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the MM is less than 300 amino acids in length.
  • Aspect 19 The activatable IL12 fusion protein of any one of aspects 1 to 17, wherein the MM is about 400 to about 900 amino acids in length.
  • Aspect 20 The activatable IL12 fusion protein of any one of the preceding aspects, wherein the MM is an scFv comprising an amino acid sequence according to SEQ ID NO: 289.
  • Aspect 21 The activatable IL12 fusion protein of any one of the preceding aspects, wherein the MM is an scFv comprising a VL domain and a VH domain, and wherein the VL domain is proximal to the DD and VH is more proximal to the L2.
  • Aspect 22 Aspect 22.
  • Aspect 23 The activatable IL12 fusion protein of any one of the preceding aspects, wherein the activatable IL12 fusion protein has about 100-fold to about 500-fold less IL12 activity than a cleavage product of the activatable IL12 fusion protein in an IL12 reporter assay.
  • Aspect 25 The activatable IL12 fusion protein of any one of aspects 1 to 20, wherein the first polypeptide comprises SEQ ID NO: 1 and the second polypeptide comprises SEQ ID NO: 2.
  • An activatable IL12 construct comprising: afirst polypeptide having a structure N'-DD1-L1-p40-C' or C'-DD1-L1-p40-N', and a second polypeptide having a structure N'-DD2-L2-p35-L3-MM-C' or C'-DD2-L2-p35-L3-MM- N'; or ii) afirst polypeptide having a structure N'-DD1-L1-p35-C' or C'-DD1-L1-p35-N' and a second polypeptide having a structure N'-DD2-L2-p40-L3-MM-C' or C'-DD2-L2-p40- L3-MM-N', wherein: a) each of L1, L2, and L3 independently comprises a cleavable moiety (CM); b) DD1 is afirst dimerization domain and DD2 is a second dimerization domain, where
  • Aspect 28 The activatable IL12 construct of aspect 27, wherein the CM is a substrate for an MMP or a serine protease, or both.
  • Aspect 29 The activatable IL12 construct of aspect 27 or aspect 28, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14.
  • Aspect 30 The activatable IL12 construct of any one of aspects 27 to 29, wherein the DD1 is at the amino terminal end of each of thefirst polypeptide and the second polypeptide.
  • Aspect 32 The activatable IL12 construct of any one of aspects 27 to 31, wherein each of the L1, the L2, and the L3 independently comprises an amino acid sequence selected from the 304 CYTX-115-PCT 4862-0152WO1 group consisting of SEQ ID NOs: 58 to 98, 101 to 282, 318-1354, and 1388-1423, including any combination thereof.
  • Aspect 33 Aspect 33.
  • Aspect 35 The activatable IL12 construct of any one of aspects 27 to 33, wherein the MM is about 400 to about 900 amino acids in length.
  • Aspect 36 The activatable IL12 construct of any one of aspects 27 to 32, 34, and 35, wherein the MM is an scFv comprising an amino acid sequence according to SEQ ID NO: 289.
  • Aspect 37 The activatable IL12 construct of any one of aspects 27 to 36, wherein the scFv comprises a VL domain and a VH domain, and wherein the VL domain is more proximal to the L3 than to a terminus of the activatable IL12 construct.
  • Aspect 38 Aspect 38.
  • the activatable IL12 construct of any one of aspects 28 to 38, has about 50- fold to about 150-fold less IL12 activity than a cleavage product of the activatable IL12 construct in an IL12 reporter assay.
  • Aspect 40 Aspect 40.
  • L1 may comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • L21 may comprise about 20 amino acids to about 60 amino acids, about 22 amino acids to about 58 amino acids, or about 24 amino acids to about 56 amino acids.
  • the activatable IL12 construct of aspect 42 wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14.
  • Aspect 44 The activatable IL12 construct of any one of aspects 41 to 43, wherein the IL12 comprises a linker between the p35 domain and the p40 domain.
  • Aspect 45 The activatable IL12 construct of any one of aspects 41 to 44, wherein the DD1 is at the carboxy terminal end of thefirst polypeptide and the DD2 is at the carboxy terminal end of the second polypeptide.
  • Aspect 46 Aspect 46.
  • Aspect 47 The activatable IL12 fusion protein of any one of aspects 41 to 46, wherein the MM is less than 300 amino acids in length.
  • Aspect 48 The activatable IL12 construct of any one of aspects 41 to 46, wherein the MM is about 400 to about 900 amino acids in length.
  • Aspect 49 Aspect 49.
  • Aspect 50 The activatable IL12 construct of any one of aspects 41 to 49, has about 100- fold to about 5-fold to 20-fold less IL12 activity than a cleavage product of the activatable IL12 construct in an IL12 reporter assay.
  • Aspect 51 The activatable IL12 construct of any one of aspects 41 to 50, wherein thefirst polypeptide comprises SEQ ID NO: 5 and the second polypeptide comprises SEQ ID NO: 6.
  • Aspect 52 The activatable IL12 construct of any one of aspects 41 to 50, wherein thefirst polypeptide comprises SEQ ID NO: 5 and the second polypeptide comprises SEQ ID NO: 6.
  • a composition comprising the activatable IL12 fusion protein or the activatable IL12 construct of any one of the aspects disclosed herein, and a pharmaceutically acceptable carrier, or a container, vial, syringe, injector pen, or a kit comprising the activatable IL12 fusion protein or the activatable IL12 construct of any one of the aspects disclosed herein, and a pharmaceutically acceptable carrier.
  • a pharmaceutically acceptable carrier or a container, vial, syringe, injector pen, or a kit comprising the activatable IL12 fusion protein or the activatable IL12 construct of any one of the aspects disclosed herein, and a pharmaceutically acceptable carrier.
  • Aspect 55 A cell comprising the nucleic acid of aspect 53 or the vector of aspect 54.
  • Aspect 56 A method of producing the activatable IL12 fusion protein or thefirst polypeptide or the second polypeptide of the activatable IL12 construct of any one of the aspects disclosed herein, comprising culturing the cell of aspect 55 in a culture medium to produce the activatable IL12 fusion protein, thefirst polypeptide, or the second polypeptide; and recovering the activatable IL12 fusion protein, thefirst polypeptide, or the second polypeptide from the culture medium.
  • Aspect 57 Aspect 57.
  • Aspect 58 A method of treating a subject in need thereof, comprising administering the activatable IL12 fusion protein or the activatable IL12 construct of any one of the aspects disclosed herein to the subject.
  • Aspect 59 The method of aspect 58, wherein the subject has a cancer, an autoimmune disorder, an inflammatory disorder, or an infectious disease.
  • Aspect 60 Aspect 60.
  • Aspect 61 The method of any one of aspects 58 to 60, further comprising administering a second therapeutic agent.
  • Aspect 62. The method of aspect 61, wherein the second therapeutic agent is a checkpoint inhibitor, an anti-neoplastic agent, or a cytotoxic agent.
  • the second therapeutic agent is an antibody against PD-L1, an antibody against PD-1, an antibody against CTLA-4, a CD47 antagonist, an ILT2 antagonist, or a SIRP ⁇ antagonist to the subject.
  • An activatable IL12 fusion protein comprising: a first IL12 subunit and a second IL12 subunit; 308 CYTX-115-PCT 4862-0152WO1 at least one of a first linking region (LR1) and a second linking region (LR2); and a half-life extending moiety (EM), wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM), wherein the first IL12 subunit is coupled directly or indirectly to the EM and the second IL-12 subunit is coupled directly or indirectly to the EM, and wherein the first IL12 subunit is coupled to the EM by the LR1, or the first IL12 subunit is coupled to the EM by the LR1 and the second IL12 subunit is coupled to the EM by the LR2.
  • CM cleavable moiety
  • Aspect 65 The activatable IL12 fusion protein of aspect 64, comprising a first polypeptide chain comprising from N-terminus to C-terminus: (i) IL12 ⁇ -LR1-EM- LR2-IL12′′; or (ii) IL12 ⁇ -IL12′′-LR1-EM; wherein the IL12 ⁇ is the first IL12 subunit and the IL12′′ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond.
  • Aspect 66 The tivatable IL12 fusion protein of any one of aspects 64-65, further comprising a masking moiety (MM).
  • Aspect 67 The tivatable IL12 fusion protein of any one of aspects 64-65, further comprising a masking moiety (MM).
  • the activatable IL12 fusion protein of aspect 66 comprising a first polypeptide chain comprising from N-terminus to C-terminus: (i) MM-LR1-IL12 ⁇ -IL12′′-LR2-EM; or (ii) IL12 ⁇ -IL12′′-LR1-MM-LR2-EM.
  • Aspect 68. The activatable IL12 fusion protein of aspect 67, wherein the LR1 and the LR2 comprise a CM.
  • An activatable IL12 construct comprising the activatable IL12 fusion protein of any one of aspects 64-68, and a second polypeptide chain comprising an EM, wherein the EM of the second polypeptide chain is dimerized with the EM of the activatable IL12 fusion protein.
  • Aspect 70. The activatable IL12 construct of aspect 69, wherein the second polypeptide comprises polypeptide chain comprising from N-terminus to C-terminus: IL12 ⁇ -LR1-EM- LR2- IL12′′.
  • Aspect 73 is an Fc domain, optionally wherein the Fc domain is an IgG Fc domain, and optionally wherein the IgG Fc domain is a human IgG Fc domain, and optionally wherein the Fc domain of the activatable IL12 fusion protein has a different amino acid sequence from the Fc domain of the second polypeptide or wherein the Fc domain of the activatable IL12 fusion protein has the same amino
  • An activatable IL12 fusion protein or an activatable IL12 construct comprising: a first IL12 subunit and a second IL12 subunit; a first linking region (LR1) and a second linking region (LR2); a half life extension moiety (EM), and a masking moiety (MM); wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM), wherein the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the MM by the LR1 and the MM is coupled to the EM by the LR2, or wherein the first IL12 subunit is coupled to the MM by the LR1, the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the EM by the LR2.
  • CM cleavable moiety
  • Aspect 74 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 72, comprising a first polypeptide chain comprising from N-terminus to C-terminus: (i) MM-LR1-IL12 ⁇ -IL12′′-LR2-EM; or (ii) IL12 ⁇ -IL12′′-LR1-MM-LR2-EM, wherein the IL12 ⁇ is the first IL12 subunit and the IL12′′ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond.
  • Aspect 75 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 73, wherein the activatable construct comprises a second polypeptide comprising an EM.
  • Aspect 76 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 74, wherein the EM of the first polypeptide chain and the second EM of the second polypeptide chain form a dimer.
  • Aspect P The activatable IL12 fusion protein of aspect 76, comprising afirst polypeptide having a structure N'-EM1-LR1-IL12’-C' or C'-EM1-LR1-IL12’-N'; and a second polypeptide having a structure N'-EM2-LR2-IL12”-LR3-MM-C' or C'-EM2-LR2-IL12”-LR3-MM-N', wherein EM1 is 310 CYTX-115-PCT 4862-0152WO1 a first half life extension moiety, EM2 is second half life extension moiety, and LR3 is a third linking region.
  • Aspect Q The activatable IL12 fusion protein of aspect P, wherein LR1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • Aspect R The activatable IL12 fusion protein of aspect Q, wherein LR2 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • Aspect S Aspect S.
  • LR3 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • the activatable IL12 fusion protein of aspect 76 comprising afirst polypeptide having a structure N'-EM1-LR1-IL12’-LR2-MM-C' or C'-EM1-LR1-IL12’-LR2-MM-N'; and a second polypeptide having a structure N'-EM2-LR3-IL12”-C' or C'-EM2-LR3-IL12”-N', wherein EM1 is a first half life extension moiety, EM2 is second half life extension moiety, and LR3 is a third linking region.
  • EM1 is a first half life extension moiety
  • EM2 is second half life extension moiety
  • LR3 is a third linking region.
  • the activatable IL12 fusion protein of aspect T wherein LR1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • Aspect V The activatable IL12 fusion protein of aspect T, wherein LR2 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • Aspect W comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • the activatable IL12 fusion protein of aspect 8T wherein LR3 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids.
  • 311 CYTX-115-PCT 4862-0152WO1 Aspect X.
  • CM1 first cleavable moiety
  • CM2 second cleavable moiety
  • CM3 third cleavable moiety
  • the activatable IL12 fusion protein or an activatable IL12 construct of aspect X having a structure comprising from N-terminus to C-terminus: i) IL12’-CM1-EM1; and ii) MM-CM2-IL12”-CM3-EM2; or wherein the IL12 ⁇ is the first IL12 subunit and the IL12′′ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond.
  • An activatable IL12 fusion protein or an activatable IL12 construct comprising: a) N ⁇ -p35-EM-CM-p40-C ⁇ ; b) N ⁇ -p40-EM-CM-p35-C ⁇ ; c) N ⁇ -p35-CM-EM-p40-C ⁇ ; d) N ⁇ -p40-CM-EM-p35-C ⁇ ; e) N ⁇ -p40-p35-CM-EM-C ⁇ ; f) N ⁇ -p40-p35-CM-MM-EM-C ⁇ ; or g) a dimer of any combination of two polypeptides of one or two of a)-d), wherein p35 is an IL12 ⁇ domain, wherein p40 is an IL12 ⁇ domain, wherein CM is a cleavable moiety, wherein EM is a half-life extending moiety, wherein N ⁇ represents the N-terminus, wherein C ⁇ represents the C
  • the activatable IL12 construct of aspect 78 comprising a dimer of: i) a first polypeptide comprising a) and a second polypeptide comprising a); ii) a first polypeptide comprising b) and a second polypeptide comprising b); 312 CYTX-115-PCT 4862-0152WO1 iii) a first polypeptide comprising c) and a second polypeptide comprising c); iv) a first polypeptide comprising d) and a second polypeptide comprising d); v) a first polypeptide comprising a) and a second polypeptide comprising b); vi) a first polypeptide comprising a) and a second polypeptide comprising c); vii) a first polypeptide comprising a) and a second polypeptide comprising d); viii) a first polypeptide comprising b) and a second polypeptide comprising c);
  • Aspect 80 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 78, wherein e) further comprises a MM and a second cleavable moiety (CM2) such that it comprises a structural arrangement of: N ⁇ -MM-CM2-p40-p35-CM-EM-C ⁇ .
  • Aspect 81 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 78, wherein f) further comprises a second cleavable moiety (CM2) such that it comprises a structural arrangement of: N ⁇ -p40-p35-CM-MM-CM2-EM-C ⁇ .
  • Aspect 82 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 78, wherein f) further comprises a second cleavable moiety (CM2) such that it comprises a structural arrangement of: N ⁇ -p40-p35-CM-MM-CM2-EM-C ⁇ .
  • the activatable IL12 fusion protein or the activatable IL12 construct of aspect 82 comprising: a) N ⁇ -p35-LR1-EM-LR2-CM-p40-C ⁇ ; b) N ⁇ -p35-EM-LR1-CM-p40-C ⁇ ; c) N ⁇ -p35-LR1-EM-CM-p40-C ⁇ ; d) N ⁇ -p40-LR1-EM-LR2-CM-p35-C ⁇ ; e) N ⁇ -p40-EM-LR1-CM-p35-C ⁇ ; f) N ⁇ -p40-LR1-EM-CM-p35-C ⁇ ; g) N ⁇ -p35-CM-LR1-EM-LR2-p
  • Aspect 84 The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-77 and 82-83, wherein the LR1, the LR2, or both the LR1 and the LR2 are each independently 7 to 45 amino acids amino acids in length.
  • Aspect 85 The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-77 and 82-83, wherein the LR1 and the LR2 are each independently at least 7 amino acids amino acids in length.
  • Aspect 86 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 85, wherein the LR1 and the LR2 are each independently 7 to 300 amino acids amino acids in length.
  • Aspect 87 The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-77 and 82-83, wherein the LR1, the LR2, or both the LR1 and the LR2 are each independently 7 to 45 amino acids
  • Aspect 88. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 87, wherein the LR1 and the LR2 are each independently 1 to 60 amino acids in length.
  • the activatable IL12 fusion protein or the activatable IL12 construct of aspect 89 wherein the LR1 and the LR2 are each independently 4 to 43 amino acids in length.
  • Aspect 91. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 90, wherein the LR1 and the LR2 are each independently 29 to 43 amino acids in length.
  • Aspect 92. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 90, wherein the LR1 and the LR2 are each independently 17 to 21 amino acids in length.
  • Aspect 93 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 89, wherein the LR1 and the LR2 are each independently 4 to 43 amino acids in length.
  • Aspect 91. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 90, wherein the LR1 and the LR2 are each independently 29 to 43 amino acids in length.
  • Aspect 94 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 93, wherein the EM is human serum albumin (HSA).
  • Aspect 95 The activatable IL12 fusion protein or the activatable IL12 construct of aspect 93, wherein the EM is an albumin binding peptide comprising the amino acid sequence QRLMEDICLPRWGCLWEDDF (SEQ ID NO: 1424).
  • Aspect 96. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-92, wherein the EM is a dimerization domain (DD).
  • Aspect 97 The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-92, wherein the EM is a dimerization domain (DD).
  • Aspect 98. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 97, wherein the Fc domain is covalently bound to a second Fc domain via at least one disulfide bond thereby forming a dimer.
  • Aspect 99. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-77 and 82-98, wherein at least one of the LR1 and the LR2 comprises a CM.
  • MMP matrix metalloprotease
  • Aspect 101. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 100, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14.
  • QXAQX1LX2XBA SEQ ID NO: 1388
  • CYTX-115-PCT 4862-0152WO1 Aspect 103.
  • Aspect 104 is a sequence selected from: SEQ ID NO: 1389, SEQ ID NO: 1394, SEQ ID NO: 1399, SEQ ID NO: 1404, SEQ ID NO: 1409, SEQ ID NO: 1414, SEQ ID NO: 1419.
  • Aspect 105 The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-99, wherein the CM comprises SEQ ID NO: 428, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 1354, SEQ ID NO: 805, SEQ ID NO: 1278, SEQ ID NO: 144.
  • Aspect 106. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 105, wherein the CM comprises SEQ ID NO: 428 or SEQ ID NO: 805.
  • Aspect 107 The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-99, wherein the CM comprises SEQ ID NO: 428, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 1354, SEQ ID NO: 805, SEQ ID NO: 1278, SEQ ID NO: 144.
  • Aspect 106. The activatable IL12 fusion
  • Aspect 108. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 107, wherein the Fab fragment is an scFv.
  • Aspect 110 Aspect 110.
  • Aspect 112. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 68-111, wherein the MM is less than 300 amino acids in length. Aspect 113.
  • Aspect 114. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 113, wherein the MM is an scFv comprising an amino acid sequence according to SEQ ID NO: 289.
  • a linker between the p40 domain and the p35 domain is 7, 8, 9, 10, 11, 12, 13, 14, or 15 amino acids in length, e.g., 7 amino acids or 15 amino acids.
  • a linking region (flexible linker or flexible linker and CM) between the MM and the IL12 is 25 to 47 amino acids in length (including any integer in the range of 25 to 47), e.g., 25, 38, or 47 amino acids.
  • a linking region (flexible linker or flexible linker and CM) between the MM and the DD is 25 to 47 amino acids in length (including any integer in the range of 25 to 47), e.g., 25, 38, or 47 amino acids.
  • the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 1354, SEQ ID NO: 805, SEQ ID NO: 1278, and SEQ ID NO: 144. [00388] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 318-1347 [00389] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 318-331.
  • the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 332-400. [00391] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 401-794. [00392] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 795-1274. 317 CYTX-115-PCT 4862-0152WO1 [00393] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1275-1347.
  • the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1388-1423.
  • OTHER EMBODIMENTS [00395] It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims. 318

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Abstract

Activatable interleukin 12 (IL12) fusion proteins and constructs are disclosed herein that contain at least one of the following structures: N'-DD-L1-MM-L2-IL12-C', C'-DD-L1-MM-L2-IL12-N', N'-DD-L1-IL12-L2-MM-C', C'-DD-L1-IL12-L2-MM-N', wherein L1 is a first linker or is absent; L2 is a second linker; DD is a dimerization domain; MM is a masking moiety; IL12 comprises an IL12α (p35) domain and an IL12β (p40) domain; N' is an amino terminus of the activatable IL12 fusion protein; and C' is a carboxy terminus of the activatable IL12 fusion protein, wherein at least one of L1 and L2 comprises a cleavable moiety (CM); or a first IL12 subunit and a second IL12 subunit; at least one of a first linking region (LR1) and a second linking region (LR2); and a half-life extending moiety (EM), wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM); or dimers thereof.

Description

CYTX-115-PCT 4862-0152WO1 ACTIVATABLE IL-12 CONSTRUCTS AND RELATED COMPOSITIONS AND METHODS CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of provisional applications U.S. 63/673,405, filed July 19, 2024, and U.S. 63/724,811, filed November 25, 2024, pursuant 35 U.S.C. § 119(e), each of which is incorporated herein by reference in their entireties. REFERENCE TO SEQUENCE LISTING The “Sequence Listing” submitted electronically concurrently herewith pursuant 37 C.F.R. § 1.821 in computer readable form via Patent Center named “4862-152WO1,” created on July 18, 2025, is 1,851,392 bytes in size, and is incorporated herein by reference. TECHNICAL FIELD [0001] The present disclosure relates to thefield of biotechnology, and more specifically, to activatable interleukin 12 (IL12) fusion proteins and activatable interleukin-12 (IL12) constructs. BACKGROUND [0002] Interleukins regulate cell growth, differentiation, and motility. They are particularly important in stimulating immune responses, such as inflammation. IL12 is a heterodimeric molecule composed of an alpha chain (the p35 subunit) and a beta chain (the p40 subunit) covalently linked by a disulfide bridge to form the biologically active 70 kDa dimer. IL12 elicits strong antitumor effects by stimulating unmodified immune cells, including T cells and natural killer (NK) cells. In particular, IL12 strongly induces IFN-γ from unmodified NK cells and activated T cells. However, IL12 therapy in humans is often accompanied by undesired side effects including toxicity,flu-like symptoms, nausea, vomiting, diarrhea, low blood pressure, arrhythmia, and death. Currently, no IL12-based therapeutic products have been approved for clinical application. [0003] Thus, an IL12 therapy having fewer of the undesired side effects reported to date would be highly desirable. SUMMARY OF THE INVENTION [0004] The present disclosure provides activatable interleukin 12 (IL12) fusion proteins and activatable IL12 constructs (“AICs”) that include one or more novel structural formats and/or masking moieties. 1 CYTX-115-PCT 4862-0152WO1 [0005] In one aspect, the present disclosure provides activatable interleukin 12 (IL12) fusion proteins comprising one or more polypeptide chains. In one aspect, the present disclosure provides activatable IL12 constructs (“AICs”) comprising two polypeptide chains. [0006] In one aspect, the present disclosure includes an activatable interleukin 12 (IL12) fusion protein comprising afirst polypeptide having a structure selected from: N'-DD-L1-MM-L2-IL12- C'; C'-DD-L1-MM-L2-IL12-N'; N'-DD-L1-IL12-L2-MM-C'; and C'-DD-L1-IL12-L2-MM-N', where L1 is afirst linker or is absent, L2 is a second linker, DD is a dimerization domain, and MM is a masking moiety. IL12 comprises an IL12α (p35) domain and an IL12β (p40) domain. N' is an amino terminus of the activatable IL12 fusion protein, and C' is a carboxy terminus of the activatable IL12 fusion protein. At least one of L1 and L2 comprises a cleavable moiety (CM). In certain aspects, L2 comprises a CM. In certain aspects, L1 comprises a CM. In certain aspects, L1 does not contain a CM. In some aspects, the activatable IL12 fusion protein can have 1.5-fold to about 1000-fold, or about 2-fold to about 100-fold, or about 100-fold to about 1000-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. In some aspects, the fusion protein may comprise a second polypeptide with a second dimerization domain (DD2), such that the DD and the DD2 may dimerize to form an activatable IL12 construct. In some aspects, the second polypeptide: (1) comprises the DD2 and (2) does not comprise the IL12 and does not comprise a CM or an MM. [0007] In one aspect, the present disclosure includes an activatable IL12 construct comprising: i) afirst polypeptide having a structure N'-DD1-L1-p40-C' or C'-DD1-L1-p40-N', and a second polypeptide having a structure N'-DD2-L2-p35-L3-MM-C' or C'-DD2-L2-p35-L3-MM-N'; or ii) a first polypeptide having a structure N'-DD1-L1-p35-C' or C'-DD1-L1-p35-N' and a second polypeptide having a structure N'-DD2-L2-p40-L3-MM-C' or C'-DD2-L2-p40-L3-MM-N', where each of L1, L2, and L3 independently comprises a cleavable moiety (CM). In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM-MM- DD1-N' or N'-p40-p35-CM-MM-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-MM-CM1-p40-p35-CM2-DD1-N' or N'-MM-CM1-p40-p35-CM2- DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-CM1-DD1- N' or N'-p40-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM- 2 CYTX-115-PCT 4862-0152WO1 CM2-p35-CM3-DD2-N' or N'-MM-CM2-p35-CM3-DD2-C'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-MM-CM1-p40-CM2-DD1-N' or N'- MM-CM1-p40-CM2-DD1-C' and a second polypeptide having a structural arrangement of C'-p35- CM3-DD2-N' or N'-p35-CM3-DD2-C'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM1-DD1-N' or N'-p40-p35-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM-CM2-DD2-N' or N'-MM-CM2- DD2-C'. DD1 is afirst dimerization domain and DD2 is a second dimerization domain, such that DD1 and DD2 may be dimerized. MM is an scFv or peptide masking moiety. In some aspects, the activatable IL12 construct can have about 50-fold to about 1000-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. [0008] According to these disclosures, for any polypeptide that has the p40 subunit and the p35 subunit on the same polypeptide chain, the disclosures are intended to include the subunits arranged in either order from N-terminus to C-terminus. For example, any of the polypeptides according to the present disclosures are intended to include a structural arrangement comprising N'-p40-p35-C' as well as a structural arrangement comprising N'-p35-p40-C'. [0009] In one aspect, the present disclosure includes an activatable IL12 construct comprising a first polypeptide having a structure N'-DD1-L1-IL12-C' or C'-DD1-L1-IL12-N'; and a second polypeptide having a structure N'-DD2-L2-MM-C' or C'-DD2-L2-MM-N', where each of L1 and L2 independently is a cleavable moiety (CM). DD1 is afirst dimerization domain and DD2 is a second dimerization domain, such that DD1 and DD2 may be dimerized. In some aspects, MM is a masking moiety that is an anti-p40 scFv. In some aspects, DD1 is more proximal to the p35 domain than to the p40 domain. In some aspects, the activatable IL12 construct can have about 10- fold to about 50-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. [0010] In one aspect, the present disclosure provides an activatable IL12 fusion protein comprising: a first IL12 subunit and a second IL12 subunit; at least one of a first linking region (LR1) and a second linking region (LR2); and a half-life extending moiety (EM), wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM), wherein the first IL12 subunit is coupled directly or indirectly to the EM and the second IL-12 subunit is coupled directly or indirectly to the EM, and wherein the first IL12 subunit is coupled to the EM by the LR1, or the 3 CYTX-115-PCT 4862-0152WO1 first IL12 subunit is coupled to the EM by the LR1 and the second IL12 subunit is coupled to the EM by the LR2. [0011] In one aspect, the present disclosure provides an activatable IL12 fusion protein comprising a first polypeptide chain comprising from N-terminus to C-terminus: IL12´-LR1-EM-LR2-IL12″; or IL12´-IL12″-LR1-EM; wherein the IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond. [0012] In one aspect, the present disclosure provides an activatable IL12 fusion protein comprising a first polypeptide chain comprising from N-terminus to C-terminus: MM-LR1-IL12´-IL12″-LR2- EM; or IL12´-IL12″-LR1-MM-LR2-EM. [0013] In one aspect, the present disclosure provides an activatable IL12 fusion protein or an activatable IL12 construct comprising: a first IL12 subunit and a second IL12 subunit; a first linking region (LR1) and a second linking region (LR2); a half life extension moiety (EM), and a masking moiety (MM); wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM), wherein the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the MM by the LR1 and the MM is coupled to the EM by the LR2, or wherein the first IL12 subunit is coupled to the MM by the LR1, the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the EM by the LR2. [0014] An activatable IL12 fusion protein or the activatable IL12 construct, comprising a first polypeptide chain comprising from N-terminus to C-terminus: MM-LR1-IL12´-IL12″-LR2-EM; or IL12´-IL12″-LR1-MM-LR2-EM, wherein the IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond. [0015] In one aspect, the present disclosure provides an activatable IL12 fusion protein or an activatable IL12 construct comprising: a) N´-p35-EM-CM-p40-C´; b) N´-p40-EM-CM-p35-C´; c) N´-p35-CM-EM-p40-C´; d) N´-p40-CM-EM-p35-C´; e) N´-p40-p35-CM-EM-C´; f) N´-p40-p35-CM-MM-EM-C´; or g) a dimer of any combination of two polypeptides of one or two of a)-d), wherein p35 is an IL12α domain, 4 CYTX-115-PCT 4862-0152WO1 wherein p40 is an IL12β domain, wherein CM is a cleavable moiety, wherein EM is a half-life extending moiety, wherein N´ represents the N-terminus, wherein C´ represents the C-terminus, wherein MM is a masking moiety, and wherein “-” comprises a linker or a direct bond. In one aspect, the present disclosure provides an activatable IL12 construct comprising a dimer of: i) a first polypeptide comprising a) and a second polypeptide comprising a); ii) a first polypeptide comprising b) and a second polypeptide comprising b); iii) a first polypeptide comprising c) and a second polypeptide comprising c); iv) a first polypeptide comprising d) and a second polypeptide comprising d); v) a first polypeptide comprising a) and a second polypeptide comprising b); vi) a first polypeptide comprising a) and a second polypeptide comprising c); vii) a first polypeptide comprising a) and a second polypeptide comprising d); viii) a first polypeptide comprising b) and a second polypeptide comprising c); ix) a first polypeptide comprising b) and a second polypeptide comprising d); or x) a first polypeptide comprising c) and a second polypeptide comprising d), wherein the EM of the first polypeptide and the EM of the second polypeptide are dimerized. [0016] In one aspect, the present disclosure provides an activatable IL12 fusion protein or the activatable IL12 construct comprising: a) N´-p35-LR1-EM-LR2-CM-p40-C´; b) N´-p35-EM-LR1-CM-p40-C´; c) N´-p35-LR1-EM-CM-p40-C´; d) N´-p40-LR1-EM-LR2-CM-p35-C´; e) N´-p40-EM-LR1-CM-p35-C´; f) N´-p40-LR1-EM-CM-p35-C´; g) N´-p35-CM-LR1-EM-LR2-p40-C´; h) N´-p35-CM-EM-LR1-p40-C´; i) N´-p35-CM-LR1-EM-p40-C´; j) N´-p40-LR1-CM-EM-LR2-p35-C´; 5 CYTX-115-PCT 4862-0152WO1 k) N´-p40-CM-EM-LR1-p35-C´; l) N´-p40-LR1-CM-EM-p35-C´; m) N´-p40-p35-CM-LR1-EM-C´; n) N´-p40-p35-CM-LR1-MM-LR2-EM-C´; or o) a dimer of any combination of two polypeptides of one or two of a)-n). [0017] In an aspect, the present disclosure provides a composition comprising the activatable IL12 fusion protein or the activatable IL12 construct of any one or combination of aspects disclosed herein. In some aspects, the composition may further comprise a pharmaceutically acceptable carrier and/or one or more pharmaceutically acceptable excipients. [0018] In some aspects, the present disclosure provides a container, vial, syringe, injector pen, or kit comprising at least one dose of the pharmaceutical composition of any one or combination of aspects disclosed herein or the composition comprising the activatable IL12 fusion protein or the activatable IL12 construct of any one or combination of aspects disclosed herein. [0019] In some aspects, the present disclosure provides a method of treating a subject in need thereof comprising administering to the subject a therapeutically effective amount of the pharmaceutical composition of any one or combination of aspects disclosed herein, the composition comprising the activatable IL12 fusion protein or the activatable IL12 construct of any one or combination of aspects disclosed herein. [0020] In some aspects, the present disclosures provides a nucleic acid encoding the activatable IL12 fusion protein or the activatable IL12 construct of any one or combination of aspects disclosed herein. In some aspects, the nucleic acid may be provided in a vector for expression in a prokaryotic or eukaryotic cell. [0021] In some aspects, the present disclosure provides a (recombinant) cell carrying the nucleic acid encoding the activatable IL12 fusion protein or the activatable IL12 construct of any one or combination of aspects disclosed herein. In some aspects, the cell is a prokaryotic cell. In some aspects, the cell is a eukaryotic cell. In some aspects, the eukaryotic cell is a mammalian cell. [0022] In some aspects, the present disclosure provides a method of producing the activatable IL12 fusion protein or the activatable IL12 construct of any one or combination of aspects disclosed herein comprising: a) culturing a cell of any one or combination of aspects disclosed here in a liquid culture medium to produce the activatable IL12 fusion protein or the activatable 6 CYTX-115-PCT 4862-0152WO1 IL12 construct; and b) recovering the activatable IL12 fusion protein or the activatable IL12 construct from the cell or the liquid culture medium. [0023] These and other aspects of the invention will be apparent upon reference to the following detailed description, claims, aspects, procedures, compounds, and/or compositions and associated background information and references, which are hereby incorporated in their entirety. BRIEF DESCRIPTION OF DRAWINGS [0024] Certain aspects disclosed herein are illustrated by way of example, and not by way of limitation, in the accompanying drawings. The description and drawings are only for the purpose of illustration and as an aid to understanding and are not intended as a definition of the limits of the activatable interleukin 12 (IL12) fusion proteins, constructs, compositions, uses, kits, and methods of the present disclosure. [0025] FIGs. 1A-1K schematically show activatable interleukin 12 (IL12) fusion proteins and constructs of the present disclosure. FIG.1A is a schematic of ProC2020. FIG. 1B is a schematic of ProC1910–1915. The key shown to the right of FIGs 1A-1B applies to all of FIGs.1A-1H. FIG. 1C shows a schematic of ProC1726, FIG. 1D shows a schematic of ProC1977–ProC1982 and ProC2695–ProC2705 and ProC1725, FIG. 1E shows a schematic of ProC1727, FIG. 1F shows a schematic of ProC670, FIG. 1G shows a schematic of ProC671, and FIG. 1H shows a schematic of an AIC comprising p40-p35-CM-MM-CM-DD, wherein the DD is dimerized with a second polypeptide that is a DD. FIG. 1I shows a schematic of an AIC with two polypeptide chains comprising p40-p35-CM-MM-CM-DD, wherein the DDs are dimerized. FIG. 1J shows a schematic of an AIC comprising p40-p35-CM-MM-CM-DD, wherein the MM is a split MM with an internal linker comprising a CM within the MM sequence according to the structure: MM’-CM- MM”, and wherein the DD is dimerized with a second polypeptide that is a DD. FIG. 1K shows a schematic of an AIC with a first polypeptide chain comprising p40-p35-CM-MM-CM-DD, wherein the MM is a split MM with an internal linker comprising a CM within the MM sequence according to the structure: MM’-CM-MM”, and a second polypeptide chain with a second MM and a CM comprising the structure MM-CM-DD, and wherein the DDs are dimerized. In another aspect, the MM in the first polypeptide construct in Fig. 1K is not a split mask. Examples of this alternative construct are in AICs ProC5805 through ProC5808. [0026] FIG. 2 shows a polyacrylamide gel electrophoresis (PAGE) image of the indicated constructs before and after treatment with MMP14. 7 CYTX-115-PCT 4862-0152WO1 [0027] FIG. 3 shows a PAGE image of the indicated constructs before and after treatment with MMP14. [0028] FIG. 4 shows a PAGE image of the indicated constructs before and after treatment with MMP14. [0029] FIG. 5 shows PAGE images of the indicated constructs before and after treatment with uPA. [0030] FIG. 6 shows IL12 activity vs. concentration curves for the indicated AICs and rhIL12. [0031] FIG. 7 shows IL12 activity vs. concentration curves for the indicated AICs and rhIL12AICs. [0032] FIG. 8 shows IL12 activity vs. concentration curves for the indicated AICs and rhIL12. [0033] FIG. 9 shows IL12 activity vs. concentration curves for the indicated AICs and rhIL12. [0034] FIG. 10 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes) and rhIL12. [0035] FIG. 11 shows PAGE images of the indicated constructs before and after treatment with MMP9. [0036] FIG. 12 shows PAGE images of the indicated constructs before and after treatment with MMP9. [0037] FIG. 13 shows PAGE images of the indicated constructs before and after treatment with MMP2 and MMP9. [0038] FIG. 14 shows PAGE images of the indicated constructs before and after treatment with MMP9. [0039] FIG. 15 shows PAGE images of the indicated constructs before and after treatment with MMP2. [0040] FIG. 16 shows PAGE images of the indicated constructs before and after treatment with MMP2. [0041] FIG. 17 shows PAGE images of the indicated construct before and after treatment with MMP2. [0042] FIG.18 shows IL12 activity vs. concentration curves for the indicated AIC both activated (cleaved) (open shapes) and uncleaved (dark shapes). [0043] FIG. 19 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes). 8 CYTX-115-PCT 4862-0152WO1 [0044] FIG. 20 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes). [0045] FIG. 21 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes). [0046] FIG. 22 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes). [0047] FIG. 23 shows IL12 activity vs. concentration curves for the indicated AICs both activated (cleaved) (open shapes) and uncleaved (dark shapes). [0048] FIG.24 shows IL12 activity vs. concentration curves for the indicated AIC both activated (cleaved) (open shapes) and uncleaved (dark shapes). [0049] FIG. 25 shows anti-tumor activity for the indicated AICs in MC38 syngeneic tumor model. [0050] FIG. 26 shows plasma cytokine levels on day 2 in MC38 tumor-bearing animals treated with IL12 AICs. [0051] FIG. 27 shows plasma cytokine levels on day 5 in MC38 tumor-bearing animals treated with IL12 AICs. [0052] FIG. 28 shows plasma alanine transaminase (ALT) and alanine aminotransferase (AST) levels on day 12 in MC38 tumor-bearing animals treated with AICs. [0053] FIG. 29 shows exemplary configurations of AICs and exemplary lengths of amino acids between the depicted elements. [0054] FIG. 30 shows exemplary AICs: ProC1725, ProC1726, ProC1727, and ProC2020. [0055] FIG. 31 shows exemplary AICs: ProC760, ProC1910 to ProC1915, ProC671, ProC1977 to ProC1982, and ProC2695 to ProC2705. [0056] FIG.32 shows exemplary AICs: ProC5152, ProC5153, ProC5150, ProC5151, ProC5585, ProC5586, ProC5587, ProC5866, ProC5581, ProC5580, ProC5589, and ProC5588. [0057] FIG. 33 shows exemplary AICs: ProC5333, ProC5334, ProC5745, ProC5867, ProC5746, ProC5868, ProC5747, ProC5874, ProC5581, and ProC5882. DETAILED DESCRIPTION [0058] While aspects of the subject matter of the present disclosure may be embodied in a variety of forms, the following description is merely intended to disclose some of these forms as specific 9 CYTX-115-PCT 4862-0152WO1 examples of the subject matter encompassed by the present disclosure. Accordingly, the subject matter of this disclosure is not intended to be limited to the forms or aspects so described. [0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Methods and materials are described herein for use in the invention disclosed herein. Other, suitable methods and materials known in the art can also be used. The materials, methods, and examples are illustrative only and not intended to be limiting. All publications, patent applications, patents, sequences, database entries, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification—including definitions—will control over text incorporated by reference. [0060] Other features and advantages of the invention will be apparent from the following detailed description andfigures, and from the claims. [0061] The article “a” or “an” refers to one or more (i.e., at least one) of the grammatical objects of the article. By way of example, “a cell” encompasses one or more cells. [0062] As used herein, “about” and “approximately”—when used to modify an amount specified in a numeric value or range—indicate that the numeric value as well as reasonable deviations from the value known to the skilled person in the art. For example, ± 20%, ± 10%, or ± 5%, are within the intended meaning of the recited value where appropriate. [0063] Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpretedflexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range, as if each numerical value and sub-range is explicitly recited. As an illustration, a numerical range of “about 0.01 to 2.0” should be interpreted to include not only the explicitly recited values of about 0.01 to about 2.0, but also include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 0.5, 0.7, and 1.5, and sub-ranges such as from 0.5 to 1.7, 0.7 to 1.5, and from 1.0 to 1.5, etc. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described. Additionally, all percentages are in weight, unless specified otherwise. 10 CYTX-115-PCT 4862-0152WO1 [0064] “Including” or “comprising” and their derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as “having” and their derivatives. [0065] “Consisting” and its derivatives, as used herein, are intended to be closed terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but exclude the presence of other unstated features, elements, components, groups, integers and/or steps. “Consisting essentially of” is intended to specify the presence of the stated features, elements, components, groups, integers, and/or steps as well as those that do not materially affect the basic and novel characteristic(s) of features, elements, components, groups, integers, and/or steps. Reference to any one of these transition terms (i.e., “comprising,” “consisting,” or “consisting essentially”) provides direct support for replacement to any of the other transition term not specifically used. For example, amending a term from “comprising” to “consisting essentially of” or “consisting of” wouldfind direct support due to this definition for any elements disclosed throughout this disclosure. Based on this definition, any element disclosed herein or incorporated by reference may be included in or excluded from the claimed invention. [0066] As used herein, a plurality of compounds, elements, or steps may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. [0067] Furthermore, certain molecules, constructs, compositions, elements, moieties, excipients, disorders, conditions, properties, steps, or the like may be discussed in the context of one specific embodiment or aspect or in a separate paragraph or section of this disclosure. It is understood that this is merely for convenience and brevity, and any such disclosure is equally applicable to and intended to be combined with any other embodiments or aspects found anywhere in the present disclosure and claims, which all form the application and claimed invention at thefiling date. For example, a list of constructs, molecules, method steps, kits, or compositions described with respect to a fusion protein, construct, composition, or method is intended to and doesfind direct support for embodiments related to fusion proteins, constructs, compositions, formulations, and methods 11 CYTX-115-PCT 4862-0152WO1 described in any other part of this disclosure, even if those fusion proteins, constructs, method steps, active agents, kits, or compositions are not re-listed in the context or section of that embodiment or aspect. [0068] The terms “cleavable moiety” and “CM” are used interchangeably herein to refer to a polypeptide, the amino acid sequence of which comprises a substrate for a protease. Exemplary cleavable moieties that are suitable for use in the activatable IL12 fusion proteins and AICs herein include any of the protease substrates that are known the art. Illustrative cleavable moieties are described in more detail below. [0069] The terms “masking moiety” or “MM” are used interchangeably herein to refer to a peptide or protein that, when positioned proximal to the p35 and/or p40 domain of IL12, interferes with binding of the IL12 to its receptor, thereby reducing or inhibiting one or more activities of an activatable IL12 fusion protein or construct of the present disclosure. In some aspects, when positioned proximal to IL12 in an activatable IL12 fusion protein or AIC, a MM interferes with binding of the IL12 to its binding partner (e.g., its receptor). [0070] “Masking efficiency” refers to the activity (e.g., EC50) of the (uncleaved) activatable IL12 fusion proteins and AICs divided by the activity of a control interleukin-12, wherein the control interleukin-12 may be a cleavage product of the activatable IL12 fusion protein or AIC, or alternatively, a recombinant IL12. An activatable IL12 fusion protein or AIC having a reduced level of at least one interleukin-12 activity has a masking efficiency that is greater than 1.5, 2, 3, 4, 5, 6, 7, 8, 9, or 10. In some aspects, the activatable IL12 fusion proteins or AICs described herein have a masking efficiency that is greater than 10, greater than 100, greater than 1000, or greater than 5000. In some aspects, the activatable IL12 fusion protein or AIC has a masking efficiency that is about 10 to about 1000, or about 10 to about 500, or about 50 to about 250, or about 50 to about 100, as measured by the ratio of the EC50 of the (uncleaved) activatable IL12 fusion protein or AIC to the EC50 of control interleukin12 in IL-2/IL-15 responsive HEK293 cells. [0071] As used herein “continuous” in the context of an amino acid sequences means two or more adjacent amino acids in the same order from the N- to C-terminal direction. [0072] “Activatable” when used in reference to a activatable IL12 fusion protein or construct, refers to an activatable IL12 fusion protein or construct that exhibits afirst level of one or more activities, whereupon exposure to a condition that causes cleavage of one or more cleavable moieties results in the generation of an activatable IL12 fusion protein or construct that exhibits a 12 CYTX-115-PCT 4862-0152WO1 second level of the one or more activities, where the second level of activity is greater than thefirst level of activity. Non-limiting examples of activities include any of the exemplary activities of an interleukin-12 described herein or known in the art. As used herein, an activatable interleukin 12 (IL12) fusion protein comprises one or more polypeptide chains and an activatable IL12 construct (“AIC”) comprises two polypeptide chains. [0073] “Mature cytokine polypeptide” refers herein to a cytokine polypeptide that lacks a signal sequence. A cytokine polypeptide (e.g., an interleukin-12 polypeptide) may be a mature cytokine polypeptide or a cytokine polypeptide with a signal peptide. Thus, the activatable IL12 fusion proteins or constructs of the present disclosure may include a mature IL12 sequence in some aspects. In some aspects, the activatable IL12 fusion proteins or constructs of the present disclosure may include a mature IL12 sequence and, additionally, a signal sequence. In some aspects, the activatable IL12 fusion proteins or constructs of the present disclosure may include sequences disclosed herein, including or lacking the signal sequences recited herein. [0074] The terms “dimerization domain” and “DD” are used interchangeably herein to refer to one member of a pair of dimerization domains, wherein each member of the pair is capable of binding to the other via one or more covalent or non-covalent interactions. Thefirst DD and the second DD may be the same or different. Exemplary DDs suitable for use as DD1 and or DD2 are described in more detail herein below. [0075] As used herein, a polypeptide, such as a cytokine (e.g., IL12) or an Fc domain, may be a “wild-type” polypeptide (i.e., a naturally-existing polypeptide) or a “variant” of the wild-type polypeptide. A variant may be a polypeptide modified by substitution, insertion, deletion and/or addition of one or more amino acids of the wild-type polypeptide, provided that the variant retains the basic function or activity of the wild-type polypeptide. In some examples, a variant may have altered (e.g., increased or decreased) function or activity compared with the wild-type polypeptide. In some aspects, the variant may be a functional fragment of the wild-type polypeptide. The term “functional fragment” means that the sequence of the polypeptide (e.g., IL12) may include fewer amino acids than the full-length polypeptide sequence, but sufficient polypeptide chain length to confer activity (e.g., IL12 activity). [0076] The term “at least [a certain] % identical to” in the context of two or more nucleic acid or amino acid sequences means that the two or more sequences have nucleotides or amino acid residues in common in the given percent when compared and aligned for maximum 13 CYTX-115-PCT 4862-0152WO1 correspondence over a comparison window or designated sequences of nucleic acids or amino acids (i.e. the sequences have at least 90 percent (%) identity). Percent identity of nucleic acid or amino acid sequences can be measured using a BLAST sequence comparison algorithm with default parameters, or by manual alignment and visual inspection (see e.g. blast.ncbi.nlm.nih.gov/Blast.cgi). Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared. For example, the % sequence identity of a given amino acid sequence A to, with, or against a given amino acid sequence B (which can alternatively be phrased as a given amino acid sequence A that has or comprises a certain % sequence identity to, with, or against a given amino acid sequence B) is calculated as follows: 100 times the fraction X/Y where X is the number of amino acid residues scored as identical matches by the sequence in that program’s alignment of A and B, and where Y is the total number of amino acid residues in B. It will be appreciated that where the length of amino acid sequence A is not equal to the length of amino acid sequence B, the % sequence identity of A to B will not equal the % sequence identity of B to A. [0077] Unless otherwise specified, the terms “polypeptide” and “recombinant polypeptide” are used interchangeably herein to refer to a polymer of amino acids that exists in a form that is not found in nature. As used herein, a “protein” can be a polymer of amino acids, but can also be a complex of two or more polymers of amino acids assembled into a quaternary structure. Polypeptides employed herein may be encoded by cDNA, recombinant RNA, recombinant DNA, or a polynucleotide of synthetic origin or some combination thereof. By virtue of its origin, or source of derivation, the “polypeptide” (1) is not in a naturally occurring organism (e.g., is not an endogenous polypeptide of a naturally occurring organism) and (2) is present in a form not found in nature. [0078] “Isolated polypeptide” means a polypeptide of cDNA, recombinant RNA, or synthetic origin, or some combination thereof, which by virtue of its origin, or source of derivation, the “isolated polypeptide” is substantially free of endogenously expressed constituents of a host cell, such as a mammalian cell or, in the case of a cell-free expression system, substantially free of cell- free expression reagents and does not occur in nature. According to aspects of the present 14 CYTX-115-PCT 4862-0152WO1 disclosure, the isolated polypeptide may be disposed in a complex comprising two or more polypeptides including wherein the complex comprises IL12. [0079] Unless otherwise specified, a “polynucleotide” as used herein shall mean a polymer of nucleotides, such as, for example, a deoxyribonucleic acid (DNA), cDNA, a ribonucleic acid (RNA), a polynucleotide of synthetic origin, and the like, or some combination thereof. [0080] Unless otherwise specified, a “nucleic acid sequence encoding a protein” includes all nucleotide sequences that are degenerate versions of each other and thus encode the same amino acid sequence. Persons of ordinary skill in the art can convert amino acid sequences to derive sequences of nucleic acids encoding the amino acid sequences using automated tools (for example, bioinformatics.org/sms2/rev_trans.html). [0081] “N-terminally,” when referring to a position of afirst domain or sequence relative to a second domain or sequence in a polypeptide primary amino acid sequence, means that thefirst domain or sequence is located closer to the N-terminus of the polypeptide primary amino acid sequence than the second domain or sequence. In some aspects, there may be additional sequences and/or domains between thefirst domain or sequence and the second domain or sequence. [0082] “C-terminally,” when referring to a position of afirst domain or sequence relative to a second domain or sequence in a polypeptide primary amino acid sequence, means that thefirst domain or sequence is located closer to the C-terminus of the polypeptide primary amino acid sequence than the second domain or sequence. In some aspects, there may be additional sequences and/or domains between thefirst domain or sequence and the second domain or sequence. [0083] “Exogenous” refers to any material introduced from or originating from outside a cell, a tissue, or an organism that is not produced by or does not originate from the same cell, tissue, or organism in which it is being introduced. [0084] As used herein, the term “linker” refers to amino acid sequences that connect or link two polypeptide sequences, e.g., that link two polypeptide domains. Exemplary linkers are described in more detail below. [0085] The terms “transduced,” “transfected,” or “transformed” refer to a process by which an exogenous nucleic acid is introduced or transferred into a cell. A “transduced,” “transfected,” or “transformed” cell (e.g., mammalian cell) is one that has been transduced, transfected, or transformed with exogenous nucleic acid (e.g., a vector) that includes an exogenous nucleic acid encoding any of the activatable IL12 fusion proteins or constructs described herein. 15 CYTX-115-PCT 4862-0152WO1 [0086] “Nucleic acid” refers to a deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), or a combination thereof, in either a single- or double-stranded form. Unless specifically limited, the term encompasses nucleic acids containing known analogues of natural nucleotides that have similar binding properties as the reference nucleotides. Unless otherwise indicated, a particular nucleic acid sequence also implicitly encompasses complementary sequences as well as the sequence explicitly indicated. In some aspects of any of the nucleic acids described herein, the nucleic acid is DNA. In some aspects of any of the nucleic acids described herein, the nucleic acid is RNA. [0087] The phrase “specifically binds” means that the activatable IL12 fusion protein or construct binds to its receptor or target and does not react with other polypeptides, or binds at much lower affinity, e.g., about or greater than 10-6 M. [0088] “Treatment” refers to ameliorating at least one symptom of a disorder. Activatable IL12 Fusion Proteins [0089] The present disclosure provides activatable IL12 fusion proteins or constructs (AICs) that comprise an interleukin 12 (IL12), a cleavable moiety (CM), and a masking moiety (MM), in which the IL12 comprises an IL12α (p35) domain and an IL12β (p40) domain. In some aspects, the p40 domain comprises the sequence: IWELKKDVYVVELDWYPDAPGEMVVLTCDTPEEDGITWTLDQSSEVLGSGKTLTIQVK EFGDAGQYTCHKGGEVLSHSLLLLHKKEDGIWSTDILKDQKEPKNKTFLRCEAKNYSGR FTCWWLTTISTDLTFSVKSSRGSSDPQGVTCGAATLSAERVRGDNKEYEYSVECQEDSA CPAAEESLPIEVMVDAVHKLKYENYTSSFFIRDIIKPDPPKNLQLKPLKNSRQVEVSWEY PDTWSTPHSYFSLTFCVQVQGKSKREKKDRVFTDKTSATVICRKNASISVRAQDRYYSS SWSEWASVPCS (SEQ ID NO: 312). In some aspects, the p40 domain comprises the sequence: MWELEKDVYVVEVDWTPDAPGETVNLTCDTPEEDDITWTSDQRHGVIGSGKTLTITVK EFLDAGQYTCHKGGETLSHSHLLLHKKENGIWSTEILKNFKNKTFLKCEAPNYSGRFTCS WLVQRNMDLKFNIKSSSSSPDSRAVTCGMASLSAEKVTLDQRDYEKYSVSCQEDVTCP TAEETLPIELALEARQQNKYENYSTSFFIRDIIKPDPPKNLQMKPLKNSQVEVSWEYPDS WSTPHSYFSLKFFVRIQRKKEKMKETEEGCNQKGAFLVEKTSTEVQCKGGNVCVQAQD RYYNSSCSKWACVPCRVRS (SEQ ID NO: 1531). [0090] In some aspects, the p35 domain comprises the sequence: 16 CYTX-115-PCT 4862-0152WO1 RNLPVATPDPGMFPCLHHSQNLLRAVSNMLQKARQTLEFYPCTSEEIDHEDITKDKTST VEACLPLELTKNESCLNSRETSFITNGSCLASRKTSFMMALCLSSIYEDLKMYQVEFKTM NAKLLMDPKRQIFLDQNMLAVIDELMQALNFNSETVPQKSSLEEPDFYKTKIKLCILLHA FRIRAVTIDRVMSYLNAS (SEQ ID NO: 313). In some aspects, the p35 domain comprises the sequence: RVIPVSGPARCLSQSRNLLKTTDDMVKTAREKLKHYSCTAEDIDHEDITRDQTSTLKTCL PLELHKNESCLATRETSSTTRGSCLPPQKTSLMMTLCLGSIYEDLKMYQTEFQAINAALQ NHNHQQIILDKGMLVAIDELMQSLNHNGETLRQKPPVGEADPYRVKMKLCILLHAFSTR VVTINRVMGYLSSA (SEQ ID NO: 1530). [0091] The activatable IL12 fusion proteins and AICs of the present disclosure contain masking moieties (MMs) that interfere with the binding of IL12 to its receptor. In some aspects, the MMs bind specifically to the p40 and/or p35 domain of the IL12. In certain aspects, the MMs bind specifically to the p40 domain in the IL12. The activatable IL12 fusion proteins and AICs also contain a CM, which, when cleaved, results in the MM being untethered from the rest of the activatable IL12 fusion protein or AIC, thus making the IL12 accessible to activate immune cells. These activatable IL12 fusion proteins and AICs exhibit a reduced level of at least one activity of IL12, but after exposure to an activation condition (e.g., protease activity, such as in a tumor microenvironment) that causes cleavage of the CM(s), the cleavage product of the activatable IL12 fusion proteins and AICs exhibit substantially restored IL12 activity. According to any one or combination of aspects disclosed herein, the activatable IL12 fusion proteins or constructs (AICs) that comprise an interleukin 12 (IL12) may be a chimeric fusion protein, e.g., one of p35 or p40 IL12 subunits is human and the other is derived from a species other than human (e.g., mouse). According to the present disclosure, activatable IL12 fusion proteins or constructs (AICs) specified as chimeric may also be the fully human equivalent. [0092] In afirst aspect, the activatable IL12 fusion protein has a structure according to the formula N'-DD-L1-MM-L2-IL12-C'. [0093] In a second aspect, the activatable IL12 fusion protein has a structure according to the formula C'-DD-L1-MM-L2-IL12-N'. [0094] In a third aspect, the activatable IL12 fusion protein has a structure according to the formula N'-DD-L1-IL12-L2-MM-C'. 17 CYTX-115-PCT 4862-0152WO1 [0095] As used herein, unless otherwise stated, each “-” between elements is a direct or indirect linkage (e.g., via a linker peptide). Thus, in some aspects, the elements directly abut each other in amino acid sequence. In alternative aspects, the elements are connected by a linker amino acid sequence. [0096] In a fourth aspect, the activatable IL12 fusion protein has a structure according to the formula C'-DD-L1-IL12-L2-MM-N'. For each of these structures: L1 is afirst linker or is absent; L2 is a second linker; DD is a dimerization domain; MM is a masking moiety; N' is the amino terminus and C' is the carboxy terminus of the activatable IL12 fusion protein; and at least one of L1 and L2 comprises a CM. In certain aspects, L2 comprises a CM. In certain aspects, L1 comprises a CM. In certain aspects, L1 does not contain a CM. In some aspects, L1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. For example, L1 may comprise 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids. In some aspects, L2 comprises about 20 to about 60 amino acids, about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids. For example, L2 may comprise 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 amino acids. In some aspects, the activatable IL12 fusion protein or AIC has about 100-fold to about 1000-fold (e.g., about 200-fold, about 300-fold, about 400 fold, about 500- fold, about 600-fold, about 700-fold, about 800-fold, or about 900-fold) less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. Non-limiting examples of activatable IL12 fusion protein and AICs according to these structural formulae are shown in FIGs. 1A-1K. [0097] In some aspects, the activatable IL12 fusion protein or AIC has a first polypeptide with a structure comprising C'-DD1-L1-MM-CM-IL12-N' and a second polypeptide comprising a DD2 dimerized to the DD1, or a first polypeptide with a structure comprising N'-DD1-L1-MM-CM- IL12-C' and a second polypeptide comprising DD2 dimerized to the DD1. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM-MM- DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. See, for example, Fig. 1A. In one aspect, an exemplary AIC has a first polypeptide having a structural 18 CYTX-115-PCT 4862-0152WO1 arrangement of C'-p40-p35-CM-MM-DD1-N' and a second polypeptide having a structural arrangement of C'-DD2-N'. In one aspect, the AIC has a first polypeptide having a structural arrangement of C'-p35-p40-CM-MM-DD1-N' or N'-p35-p40-CM-MM-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. In alternative aspects, the positions of the p35 and p40 subunits are reversed. [0098] In some aspects, the CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2). In some aspects, the activatable IL12 fusion protein or AIC has a first polypeptide comprising C'-DD1-CM1-IL12- CM2-MM-N' or a first polypeptide comprising N'-DD1-CM1-IL12-CM2-MM-C', and a second polypeptide comprising DD2 dimerized to the DD1, In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of N'-MM-CM1-p40-p35-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. See, for example, Fig. 1B. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-MM-CM1- p40-p35-CM2-DD1-N' and a second polypeptide having a structural arrangement of C'-DD2-N'. In one aspect, the AIC has a first polypeptide having a structural arrangement of C'-MM-CM1- p35-p40-CM2-DD1-N' or N'-MM-CM1-p35-p40-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. In alternative aspects, the positions of the p35 and p40 subunits are reversed. [0099] In some aspects, the activatable IL12 fusion protein or AIC comprises a first half life extension moiety (EM1), a second half life extension moiety (EM2), a first linking region (LR1), a second linking region (LR2), and a third linking region (LR3). In some aspects, the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure N'-EM1-LR1-IL12’-C' or C'- EM1-LR1-IL12’-N'; and a second polypeptide having a structure N'-EM2-LR2-IL12”-LR3-MM- C' or C'-EM2-LR2-IL12”-LR3-MM-N'. In some aspects, EM1 is a DD and EM2 is a DD. In some aspects, EM1 and EM2 are dimerized. In some aspects, LR1, LR2, and LR3 each independently comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids amino acids. In some aspects, the activatable IL12 fusion protein or AIC comprises a first polypeptide having a structural arrangement of C'-IL12’-CM1- DD1-N' or N'-IL12’-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM-CM2-IL12”-CM3-DD2-N' or N'-MM-CM2-IL12”-CM3-DD2-C'. In some aspects, the 19 CYTX-115-PCT 4862-0152WO1 IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-CM1-DD1-C' and a second polypeptide having a structural arrangement of N'-MM-CM2-p35-CM3-DD2-C'. See, for example, Fig. 1C. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-CM1-DD1-N' and a second polypeptide having a structural arrangement of C'-MM-CM2-p35-CM3-DD2-N'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35-CM1-DD1-N' or N'-p35-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM-CM2-p40-CM3-DD2-N' or N'- MM-CM2-p40-CM3-DD2-C'. [00100] In some aspects, the activatable IL12 fusion protein or AIC comprises a first half life extension moiety (EM1), a second half life extension moiety (EM2), a first linking region (LR1), a second linking region (LR2), and a third linking region (LR3). In some aspects, the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure N'-EM1-LR1-IL12’-LR2- MM-C' or C'-EM1-LR1-IL12’-LR2-MM-N'; and a second polypeptide having a structure N'-EM2- LR3-IL12”-C' or C'-EM2-LR3-IL12”-N'. In some aspects, LR1, LR2, and LR3 each independently comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids amino acids. In some aspects, the activatable IL12 fusion protein or AIC has a first polypeptide having a structural arrangement of N'-MM-CM1-IL12″-CM2-EM1-C' or C'-MM-CM1-IL12″-CM2-EM1-N' and a second polypeptide having a structural arrangement of N'-IL12´-CM3-EM2-C' or C'-IL12´-CM3-EM2- N'. In some aspects, the IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit. In some aspects, EM1 and EM2 are dimerized. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of N'-MM-CM1-p40-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-p35-CM3-DD2-C'. See, for example, Fig. 1D. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'- MM-CM1-p40-CM2-DD1-N' and a second polypeptide having a structural arrangement of C'-p35- CM3-DD2-N'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-MM-CM1-p35-CM2-DD1-N' or N'-MM-CM1-p35-CM2-DD1-C' and a second polypeptide having a structural arrangement of C'-p40-CM3-DD2-N' or N'-p40-CM3-DD2-C'. 20 CYTX-115-PCT 4862-0152WO1 [00101] In some aspects, the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure comprising N'-DD1-L1-IL12-C' or C'-DD1-L1-IL12-N'; and a second polypeptide having a structure comprising N'-DD2-L2-MM-C' or C'-DD2-L2-MM-N'. In some aspects, DD1 and DD2 are dimerized. In some aspects, L1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. For example, L1 may comprise 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids. In some aspects, L2 comprises about 20 amino acids to about 60 amino acids, about 22 amino acids to about 58 amino acids, or about 24 amino acids to about 56 amino acids. For example, L2 may comprise 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 amino acids. In some aspects, the activatable IL12 fusion protein or AIC has afirst polypeptide having a structural arrangement of C'-IL12-CM1-DD1-N' or N'-IL12-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM-CM2-DD2-N' or N'-MM-CM2-DD2-C'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM1-DD1- C' and a second polypeptide having a structural arrangement of N'-MM-CM2-DD2-C'. See, for example, Fig. 1E. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM1-DD1-N' and a second polypeptide having a structural arrangement of C'-MM-CM2-DD2-N'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35-p40-CM1-DD1-N' or N'-p35-p40-CM1-DD1-C' and a second polypeptide having a structural arrangement of C'-MM-CM2-DD2-N' or N'-MM-CM2- DD2-C'. In alternative aspects, the positions of the p35 and p40 subunits are reversed. [00102] FIG.1F shows an AIC with a first polypeptide having a structural arrangement of N'-p40- p35-CM1-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. In some aspects, an AIC comprises a first polypeptide having a structural arrangement of C'-p40- p35-CM1-DD1-N' and a second polypeptide having a structural arrangement of C'-DD2-N'. FIG. 1G shows an AIC with a first polypeptide having a structural arrangement of N'-p40-CM1-DD1- C' and a second polypeptide having a structural arrangement of N'-p35-CM1-DD1-C'. In some aspects, an AIC comprises a first polypeptide having a structural arrangement of C'-p40-CM1- DD1-N' and a second polypeptide having a structural arrangement of C'-p35-CM1-DD1-N'. 21 CYTX-115-PCT 4862-0152WO1 [00103] In some aspects, the CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2). In some aspects, the activatable IL12 fusion protein or AIC has a first polypeptide comprising C'-DD1-CM1-MM- CM2-IL12-N' or a first polypeptide comprising N'-DD1-CM1-MM-CM2-IL12-C', and a second polypeptide comprising DD2 dimerized to the DD1. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM1-MM-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. See, for example, Fig. 1H. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35- CM1-MM-CM2-DD1-N' and a second polypeptide having a structural arrangement of C'-DD2-N'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35- p40-CM1-MM-CM2-DD1-N' or N'-p35-p40-CM1-MM-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-DD2-C'. In alternative aspects, the positions of the p35 and p40 subunits are reversed. [00104] In some aspects, the activatable IL12 fusion protein or AIC comprises a first masking moiety (MM1), a second masking moiety (MM2), a third linker (L3), and a fourth linker (L4). In some aspects, the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure N'-DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2-IL12-N', and a second polypeptide having a N'-DD2-L3-MM2-L4-IL12-C' or C'-DD2-L3-MM2-L4-IL12-N', In some aspects, L1 and L3 each independently comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. For example, L1 and L3 may independently comprise 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids. In some aspects, L2 and L4 each independently comprise about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids. For example, L2 and L4 may independently comprise 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, or 54 amino acids. In some aspects, the CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2), a third cleavable moiety (CM3), and a fourth cleavable moiety (CM4). In some aspects, the activatable IL12 fusion protein or AIC has a first polypeptide comprising C'- DD1-CM1-MM1-CM2-IL12-N' and a second polypeptide comprising C'-DD2-CM3-MM2-CM4- 22 CYTX-115-PCT 4862-0152WO1 IL12-N', or a first polypeptide comprising N'-DD1-CM1-MM1-CM2-IL12-C' and a second polypeptide comprising N'-DD2-CM3-MM2-CM4-IL12-C'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM1-MM-CM2-DD1-C' and a second polypeptide having a structural arrangement of N'-p40-p35-CM3-MM-CM4-DD2-C'. See, for example, Fig. 1I. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM1-MM-CM2-DD1-N' and a second polypeptide having a structural arrangement of C'-p40-p35-CM3-MM-CM4-DD2-N'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35-p40-CM1-MM-CM2-DD1-N' or N'-p35- p40-CM1-MM-CM2-DD1-C' and a second polypeptide having a structural arrangement of C'-p35- p40-CM3-MM-CM4-DD2-N' or N'-p35-p40-CM3-MM-CM4-DD2-C'. In alternative aspects, the positions of the p35 and p40 subunits are reversed. [00105] In some aspects, the activatable IL12 fusion protein or AIC has afirst polypeptide having a structure N'-DD1-L1-MM-L2-IL12-C' or C'-DD1-L1-MM-L2-IL12-N', and a second polypeptide having a structure comprising: N'-DD2-C' or C'-DD2-N'. In some aspects, the MM comprises a first sequence (MM’) and a second sequence (MM”), and the MM further comprises the CM within the MM sequence according to the structure comprising: MM’-CM-MM”. In some aspects, the CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2), and a third cleavable moiety (CM3). In some aspects, the activatable IL12 fusion protein or AIC has a first polypeptide comprising C'-DD1- CM1-MM-CM2-IL12-N' and a second polypeptide comprising N'-DD2-C' or a first polypeptide comprising N'-DD1-CM1-MM-CM2-IL12-C' and a second polypeptide comprising N'-DD2-C'. In some aspects, the MM comprises a first sequence (MM’) and a second sequence (MM”), and the MM further comprises the CM3 within the MM sequence according to the structure comprising: MM’-CM3-MM”. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40-p35-CM1-MM’-CM3-MM”-CM2-DD1-C' and a second polypeptide having a structural arrangement N'-DD2-C'. See, for example, Fig.1J. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM1- MM’-CM3-MM”-CM2-DD1-N' and a second polypeptide having a structural arrangement C'- DD2-N'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35-p40-CM1-MM’-CM3-MM”-CM2-DD1-N' or N'-p35-p40-CM1-MM’-CM3-MM”- 23 CYTX-115-PCT 4862-0152WO1 CM2-DD1-C' and a second polypeptide having a structural arrangement N'-DD2-C' or C'-DD2- N'. [00106] In some aspects, the MM is a first cleavable moiety (MM1) and the activatable IL12 fusion protein or AIC further comprises a second masking moiety (MM2) and a third linker (LR3). In some aspects, the activatable IL12 fusion protein or AIC has a first polypeptide comprising N'- DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2-IL12-N'; and a second polypeptide having a structure N'-DD2-L3-MM2-C' or C'-DD2-L3-MM2-N'. In some aspects, the MM1 comprises a first sequence (MM’) and a second sequence (MM”), and the MM1 further comprises the CM within the MM1 sequence according to the structure comprising: MM1’-CM-MM1”. In some aspects, L1 and L3 each independently comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. For example, L1 and L3 may independently comprise 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids. In some aspects, L2 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids. For example, L2 may comprise 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, or 54 amino acids. In some aspects, the CM is a first cleavable moiety (CM1) and the activatable IL12 fusion protein or AIC further comprises a second cleavable moiety (CM2), a third cleavable moiety (CM3), and a fourth cleavable moiety (CM4). In some aspects, the first polypeptide comprises C'-DD1-CM1-MM1-CM2-IL12-N' and the second polypeptide comprises C’DD2-CM3-MM2-N’, or the first polypeptide comprises N'-DD1-CM1-MM1-CM2-IL12-C' and the second polypeptide comprises N’-DD2-CM3-MM2-N’. In some aspects, the MM1 comprises a first sequence (MM1’) and a second sequence (MM1”), and wherein the MM1 optionally further comprises the CM4 within the MM1 according to the structure comprising: MM1’-CM4-MM1”. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of N'-p40- p35-CM1-MM1’-CM4-MM1”-CM2-DD1-C' and a second polypeptide having a structural arrangement N'-MM2-CM3-DD2-C'. See, for example, Fig.1K. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p40-p35-CM1-MM1’-CM4-MM1”- CM2-DD1-N' and a second polypeptide having a structural arrangement C'-MM2-CM3-DD2-N'. In one aspect, an exemplary AIC has a first polypeptide having a structural arrangement of C'-p35- 24 CYTX-115-PCT 4862-0152WO1 p40-CM1-MM1’-CM4-MM1”-CM2-DD1-N' or N'-p35-p40-CM1-MM1’-CM4-MM1”-CM2- DD1-C' and a second polypeptide having a structural arrangement N'-MM2-CM3-DD2-C' or C'- MM2-CM3-DD2-N'. [00107] In some aspects, the MM is an anti-p40 scFv. In some aspects, the MM is an anti-p35 scFv. In some aspects, the MM is an antibody that binds to each of p35 and p40. In some aspects, the MM is an antibody with a first binding domain that binds to p35 and a second binding domain that binds to p40. [00108] Although the activatable IL12 fusion proteins described in the immediately preceding paragraph may exist as monomers, their DDs make it possible for them to exist as dimers as well. For example, in one aspect, they exist as heterodimers (i.e., not as homodimers). By way of non- limiting example, FIG.1A depicts an AIC in which one monomer follows the formula N'-p40-L1- p35-CM-MM-L2-DD-C', while the other monomer is a solitary DD, i.e., the second monomer consists of a DD. This construct is illustrative of a second polypeptide that comprises a DD but does not comprise and IL12, MM, or CM substituent. By way of further non-limiting examples, dimeric AICs may comprise afirst and a second polypeptide, where thefirst polypeptide may comprise SEQ ID NO: 1 and the second polypeptide may comprise SEQ ID NO: 2; or thefirst polypeptide may comprise SEQ ID NO: 7 and the second polypeptide may comprise SEQ ID NO: 8; or thefirst polypeptide may comprise SEQ ID NO: 9 and the second polypeptide may comprise SEQ ID NO: 10; or thefirst polypeptide may comprise SEQ ID NO: 11 and the second polypeptide may comprise SEQ ID NO: 12; or thefirst polypeptide may comprise SEQ ID NO: 13 and the second polypeptide may comprise SEQ ID NO: 14; or thefirst polypeptide may comprise SEQ ID NO: 15 and the second polypeptide may comprise SEQ ID NO: 16; or thefirst polypeptide may comprise SEQ ID NO: 17 and the second polypeptide may comprise SEQ ID NO: 18. In other aspects, they exist as homodimers. [00109] In afifth aspect, the AIC is a dimer comprising afirst polypeptide with a structure N'- DD1-L1-p40-C' or C'-DD1-L1-p40-N', and a second polypeptide with a structure N'-DD2-L2-p35- L3-MM-C' or C'-DD2-L2-p35-L3-MM-N'. [00110] In a sixth aspect, the AIC is a dimer comprising afirst polypeptide with a structure N'- DD1-L1-p35-C' or C'-DD1-L1-p35-N' and a second polypeptide with a structure N'-DD2-L2-p40- L3-MM-C' or C'-DD2-L2-p40-L3-MM-N'. For each of these structures: each of L1, L2, and L3 independently comprises a CM; DD1 is afirst dimerization domain and DD2 is a second 25 CYTX-115-PCT 4862-0152WO1 dimerization domain, where DD1 and DD2 are dimerized; MM is an scFv or peptide masking moiety; N' is the AIC amino terminus; and C' is the AIC carboxy terminus. In some aspects, the AIC has about 50-fold to about 1000-fold (e.g., about 100-fold, about 200-fold, about 300-fold, about 400 fold, about 500-fold, about 600-fold, about 700-fold, about 800-fold, or about 900-fold) less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. Non- limiting examples of AICs according to these structural formulae are shown in FIGs. 1C and 1D. By way of further non-limiting examples, AICs may comprise afirst and a second polypeptide, where thefirst polypeptide may comprise SEQ ID NO: 3 and the second polypeptide may comprise SEQ ID NO: 4; or thefirst polypeptide may comprise SEQ ID NO: 19 and the second polypeptide may comprise SEQ ID NO: 20; or thefirst polypeptide may comprise SEQ ID NO: 21 and the second polypeptide may comprise SEQ ID NO: 22; or thefirst polypeptide may comprise SEQ ID NO: 23 and the second polypeptide may comprise SEQ ID NO: 24; or thefirst polypeptide may comprise SEQ ID NO: 25 and the second polypeptide may comprise SEQ ID NO: 26; or thefirst polypeptide may comprise SEQ ID NO: 27 and the second polypeptide may comprise SEQ ID NO: 28; or thefirst polypeptide may comprise SEQ ID NO: 29 and the second polypeptide may comprise SEQ ID NO: 30; or thefirst polypeptide may comprise SEQ ID NO: 31 and the second polypeptide may comprise SEQ ID NO: 32; or thefirst polypeptide may comprise SEQ ID NO: 33 and the second polypeptide may comprise SEQ ID NO: 34; or thefirst polypeptide may comprise SEQ ID NO: 35 and the second polypeptide may comprise SEQ ID NO: 36; or thefirst polypeptide may comprise SEQ ID NO: 37 and the second polypeptide may comprise SEQ ID NO: 38; or thefirst polypeptide may comprise SEQ ID NO: 39 and the second polypeptide may comprise SEQ ID NO: 40; or thefirst polypeptide may comprise SEQ ID NO: 41 and the second polypeptide may comprise SEQ ID NO: 42; or thefirst polypeptide may comprise SEQ ID NO: 43 and the second polypeptide may comprise SEQ ID NO: 44; or thefirst polypeptide may comprise SEQ ID NO: 45 and the second polypeptide may comprise SEQ ID NO: 46; or thefirst polypeptide may comprise SEQ ID NO: 47 and the second polypeptide may comprise SEQ ID NO: 48; or thefirst polypeptide may comprise SEQ ID NO: 49 and the second polypeptide may comprise SEQ ID NO: 50; or thefirst polypeptide may comprise SEQ ID NO: 51 and the second polypeptide may comprise SEQ ID NO: 52. [00111] In a seventh aspect, the AIC is a dimer comprising afirst polypeptide with a structure N'- DD1-L1-IL12-C' or C'-DD1-L1-IL12-N' and a second polypeptide with a structure N'-DD2-L2- 26 CYTX-115-PCT 4862-0152WO1 MM-C' or C'-DD2-L2-MM-N'. For each of these structures, each of L1 and L2 independently is a CM; DD1 is afirst dimerization domain and DD2 is a second dimerization domain; DD1 is more proximal to the p35 domain than to the p40 domain; DD1 and DD2 are dimerized; MM is an anti- p40 scFv; N' is the AIC amino terminus; and C' is the AIC carboxy terminus. In some aspects, the AIC has about 10-fold to about 50-fold (e.g., about 20-fold, about 30-fold, or about 40-fold) less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. Non-limiting examples of AICs according to these structural formulae are shown in FIGs. 1D-1E. By way of further non-limiting examples, an AIC comprises afirst and a second polypeptide, where thefirst polypeptide comprises SEQ ID NO: 5 and the second polypeptide comprises SEQ ID NO: 6. [00112] In some aspects, activatable IL12 fusion proteins or AICs of the present disclosure selectively activate upon exposure to diseased tissue, and not in normal tissue. Following activation of the activatable IL12 fusion protein or AIC upon cleavage of the CM(s), IL12 activity is restored indicating that released MM(s) are not bound to the IL12 after cleavage and do not interfere or compete with the IL12 for binding to its target. As such, the activatable IL12 fusion proteins or AICs have the potential for conferring the benefit of IL12-based therapy, while avoiding the toxicity associated with certain IL12-based therapies and improved pharmacokinetics. [00113] In some aspects, the activatable IL12 fusion protein or AIC is characterized by having an EC50 that is at least 1000-, 2000-, 3000-, 4000-, 5000-, or 6000-fold greater than the EC50 of recombinant wild type IL-12, as measured in an IL12 reporter assay. [00114] In an activatable IL12 fusion protein or AIC, an MM may be coupled to IL12 by a CM and optionally one or more linkers, as described in more detail herein. Before activation, the MM inhibits the IL12 from binding to its receptor. When activated (i.e., when the CM is cleaved by a protease), however, the MM does not substantially or significantly interfere with IL12 binding to its cognate receptor. [00115] An MM may be coupled to the IL12 either directly or indirectly, e.g., via one or more linkers. Alternatively, an MM may be coupled, either directly or indirectly, to a component of the activatable IL12 fusion protein or AIC that is not the IL12. For example, the MM may be coupled, either directly or indirectly, with a DD. In either case, in the tertiary or quaternary structure of the activatable IL12 fusion protein or AIC overall, the MM is positioned (e.g., proximal to the IL12 to be masked) so as to mask the IL12. 27 CYTX-115-PCT 4862-0152WO1 [00116] In some aspects, the activatable IL12 fusion protein or AIC is characterized by a reduction in at least one activity of IL12. In some aspects, the at least one activity is the binding affinity (KD) of the IL12 for its cognate receptor as determined using surface plasmon resonance (e.g., performed in phosphate buffered saline at 25°C). In certain embodiments, the at least one activity is the level of proliferation of T cells or NK cells. [00117] In some aspects, the activatable IL12 fusion protein or AIC is characterized by at least a 2-fold reduction in at least one IL12 activity as compared to the control level of the at least one IL12 activity. In some aspects, the activatable IL12 fusion protein or AIC is characterized by at least a 5-fold reduction in at least one activity of the IL12 as compared to the control level of the at least one activity of the IL12. In some aspects, the activatable IL12 fusion protein or AIC is characterized by at least a 10-fold reduction in at least one activity of the IL12 as compared to the control level of the at least one activity of the IL12. In some aspects, the activatable IL12 fusion protein or AIC is characterized by at least a 20-fold reduction in at least one activity of the IL12 as compared to the control level of the at least one activity of the IL12. In some aspects, the activatable IL12 fusion protein or AIC is characterized by at least a 30-fold, 40-fold, 50-fold, 60- fold, 70-fold, 80-fold, 90-fold, 100-fold, 500-fold, or 1000-fold reduction in at least one activity of the IL12 as compared to the control level of the at least one activity of the IL12. In some aspects, the activatable IL12 fusion protein or AIC is characterized by at least a 1- to 20-fold reduction, a 200- to 500-fold reduction, a 300- to 500-fold reduction, a 400- to 500-fold reduction, a 500- to 600-fold reduction, a 600- to 700-fold reduction, a 150- to 1000-fold reduction, a 100- to 1500- fold reduction, a 200- to 1500-fold reduction, a 300- to 1500-fold reduction, a 400- to 1500-fold reduction, a 500- to 1500-fold reduction, a 1000- to 1500-fold reduction, a 100- to 1000-fold reduction, a 200- to 1000-fold reduction, a 300- to 1000-fold reduction, a 400- to 1000-fold reduction, a 500- to 1000-fold reduction, a 100- to 500-fold reduction, a 20- to 50-fold reduction, a 30- to 50-fold reduction, a 40- to 50-fold reduction, a 100- to 400-fold reduction, a 200- to 400- fold reduction, or a 300- to 400-fold reduction , a 100- to 300-fold reduction, a 200- to 300-fold reduction, or a 100- to 200-fold reduction in at least one activity of the IL12 as compared to the control level of the at least one activity of the IL12. [00118] Following exposure to one or more targeted protease activities, an activatable IL12 fusion protein or AIC of the present disclosure generates a cleavage product that comprises the at least one activity of the IL12. In some aspects, the control level is an EC50 value of the wild type 28 CYTX-115-PCT 4862-0152WO1 mature IL12, and wherein ratio of EC50 (cleavage product) to EC50 (wild type control level) is less than about 10, or less than about 9, or less than about 8, or less than about 7, or less than about 6, or less than about 5, or less than about 4, or less than about 3, or less than about 2, or less than about 1.5, or equal to about 1. In some aspects, the EC50 of the cleavage product is approximately the same as the EC50 of the wild type mature IL12, demonstrating that following cleavage, the IL12 activity is fully recovered, or nearly fully recovered. In some aspects, the ratio of the EC50 of the cleavage product to the EC50 of the wildtype control is about 1 to about 10, or about 2 to about 8, or about 3 to about 7, or about 4 to about 6, demonstrating good recovery of IL12 activity following protease activation. IL-12 moieties in the activatable IL12 fusion proteins and AICs of the present disclosure undergo substantial activation following exposure of the activatable IL12 fusion protein or AIC to the targeted protease(s). In some aspects, the % activation of IL12 is at least about 10%. Percent activation is calculated as the EC50 of the recombinant IL-12 divided by the EC50 of the cleavage product times 100, where each EC50 is determined in accordance with the method of Example 3. In some aspects the % activation is at least about 15%, 20%, 25%, 30%, 40%, 45%, 50%, 60%, 70%, 75%, 80%, 85%, or 90%. [00119] In some aspects, the control level of the at least one activity of the IL12 is the activity of the IL12 released from the activatable IL12 fusion protein or AIC following cleavage of the CM by the protease(s) (the “cleavage product”). In some aspects, the control level of the at least one activity of the IL12 is the activity of a corresponding wild type mature IL12 (e.g., recombinant wild type mature IL12). [00120] In some aspects, incubation of the activatable IL12 fusion protein or AIC with the protease yields a cleavage product, where one or more activities of IL12 of the cleavage product are greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC (when uncleaved). In some aspects, one or more activities of IL12 of the cleavage product are at least 1.5-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC. In some aspects, one or more activities of IL12 of the cleavage product are at least 2-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC. In some aspects, one or more activities of IL12 of the cleavage product are at least 5-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC. In some aspects, one or more activities of IL12 of the cleavage product are at least 10-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC. In some aspects, one or more 29 CYTX-115-PCT 4862-0152WO1 activities of IL12 of the cleavage product are at least 20-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC. In some aspects, one or more activities of IL12 of the cleavage product are at least 1- to 20-fold greater, 2- to 20-fold greater, 3- to 20-fold greater, 4- to 20-fold greater, 5- to 20-fold greater, 10- to 20-fold greater, 15- to 20-fold greater, 1- to 15-fold greater, 2- to 15-fold greater, 3- to 15-fold greater, 4- to 15-fold greater, 5- to 15-fold greater, 10- to 15-fold greater, 1- to 10-fold greater, 2- to 10-fold greater, 3- to 10-fold greater, 4- to 10-fold greater, 5- to 10-fold greater, 1- to 5-fold greater, 2- to 5-fold greater, 3- to 5-fold greater, 4- to 5-fold greater, 1- to 4-fold greater, 2- to 4-fold greater, 3- to 4-fold greater, 1- to 3-fold greater, 2- to 3-fold greater, or 1- to 2-fold greater than the one or more activities of IL12 of the activatable IL12 fusion protein or AIC. [00121] In some aspects, an activatable IL12 fusion protein or AIC may include a signal sequence. Signal sequences are not particularly limited. Some non-limiting examples of signal sequences include, e.g., MRAWIFFLLCLAGRALA (SEQ ID NO: 99), MALTFALLVALLVLSCKSSCSVG (SEQ ID NO: 100), METDTLLLWVLLLWVPGSTG (SEQ ID NO: 288). [00122] Various exemplary aspects of these activatable IL12 fusion proteins or AICs are described and depicted herein and can be used in any combination in the methods provided herein without limitation. Exemplary aspects of the activatable IL12 fusion proteins or AICs and methods of making and using activatable IL12 fusion proteins or AICs are described below. [00123] In some aspects, the present disclosure includes activatable IL12 fusion proteins that consist of a single polypeptide chain. In some aspects, this single polypeptide chain possesses a DD, but nonetheless exists and functions in an undimerized state. In some aspects, these activatable IL12 fusion proteins have: at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1; at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 7; at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least 30 CYTX-115-PCT 4862-0152WO1 about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 9; at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 11; at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 13; or at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 15; or at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 17. AICs [00124] In some aspects, an AIC as described herein is a dimer comprising afirst polypeptide and a second polypeptide. Dimerization of the monomeric components is facilitated by a pair of dimerization domains. In some aspects, these dimers are heterodimers, in which the two polypeptides are not identical. [00125] In some aspects, the AICs comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 31 CYTX-115-PCT 4862-0152WO1 99%, or even 100% sequence identity to SEQ ID NO: 2; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 7 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 8; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 9 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 10; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 11 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 12; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 13 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, 32 CYTX-115-PCT 4862-0152WO1 at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 14; or a first polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 15 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 16; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 17 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 18. [00126] In some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 3 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 4; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, 33 CYTX-115-PCT 4862-0152WO1 or even 100% sequence identity to SEQ ID NO: 19 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 20; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 21 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 22; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 23 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 24; or a first polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 25 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 26; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, 34 CYTX-115-PCT 4862-0152WO1 at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 27 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 28; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 29 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 30; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 31 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 32; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 33 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 34; or afirst polypeptide having at 35 CYTX-115-PCT 4862-0152WO1 least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 35 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 36; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 37 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 38; or a first polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 39 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 40; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 41 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 36 CYTX-115-PCT 4862-0152WO1 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 42; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 43 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 44; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 45 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 46; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 47 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 48; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 49 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, 37 CYTX-115-PCT 4862-0152WO1 at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 50; or afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 51 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 52. [00127] In some aspects, the AIC comprises afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 5 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 6. [00128] In some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1362 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 8; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, 38 CYTX-115-PCT 4862-0152WO1 at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1363 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 10; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1364 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 12; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1365 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 14; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1366 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, 39 CYTX-115-PCT 4862-0152WO1 or even 100% sequence identity to SEQ ID NO: 16; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1367 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 18; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1368 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 20; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1369 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 22; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1370 and a second polypeptide having at least about 60%, 40 CYTX-115-PCT 4862-0152WO1 at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 24; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1371 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 26; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1372 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 28; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1373 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 30; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least 41 CYTX-115-PCT 4862-0152WO1 about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1374 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 32; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1375 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 34; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1376 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 36; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1377 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least 42 CYTX-115-PCT 4862-0152WO1 about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 38; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1378 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 40; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1379 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 42; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1380 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 44; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1381 and 43 CYTX-115-PCT 4862-0152WO1 a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 46; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1382 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 48; in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1383 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 50; or in some aspects, the AIC comprises: afirst polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 1384 and a second polypeptide having at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to SEQ ID NO: 52. In some aspects, a AIC polypeptide may comprise at least about 60%, at least about 65%, at least about 70%, at least about 75%, at 44 CYTX-115-PCT 4862-0152WO1 least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or even 100% sequence identity to a sequence according to SEQ ID NOs: 1–54 or 1532, 1533, 1536, 1537, 1540, 1541, 1544, 1545, 1548, 1550, 1552, 1553, 1556, 1557, 1560, 1561, 1564, 1565, 1568, 1569, 1572, 1573, 1576, 1577, 1580, 1581, 1584, 1585, 1588, 1590, 1592, 1593, 1596, 1597, 1600, 1601, 1604, 1605, 1608, 1609, 1612, 1613, 1616, 1617, 1620, 1621, 1624, 1625, 1628, 1629, 1632, 1633, 1636, 1637, 1640, 1641, 1644, 1645, 1648, 1649, 1652, 1653, 1656, 1657, 1658, 1659, 1660, 1661, 1662, 1663, 1664, or 1665. [00129] In some aspects, one or both of thefirst and second polypeptides each independently further comprise additional elements, such as, for example, one or more linkers, spacers, and the like. The additional elements are described below in more detail. [00130] The AIC structure was discovered to be highly effective at reducing IL12 activity in a way that does not lead to substantially impaired activity after activation. The IL12 activity in the AIC may be reduced by both the structure of the AIC (e.g., the dimer structure) and the MMs. In some aspects, the activation condition for the AICs described herein is exposure to one or more proteases that cleave the MM from the IL12. For example, the one or more proteases may cleave the CM between the IL12 and the MM. Additionally or alternatively, the one or more proteases may cleave the CM between the IL12 and the DD. The CM may also be provided within the MM sequence according to the structure MM’-CM-MM” such that MM’-CM-MM” has masking activity and the one or more proteases may cleave the CM within the MM. As demonstrated in the Examples, activation of the AIC resulted in substantial recovery of IL12 activity. [00131] In some aspects, when an AIC of the present disclosure is in the presence of a natural binding partner of the IL12 (e.g., its receptor), either no binding or substantially no binding of the IL12 to its natural binding partner is observed. For example, in some aspects no more than 0.001%, 0.01%, 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or 50% binding of the IL12 to its binding partner, as compared to the binding of a control IL12, i.e., recombinant IL12, for at least 2, 4, 6, 8, 12, 28, 24, 30, 36, 48, 60, 72, 84, 96 hours, or 5, 10, 15, 30, 45, 60, 90, 120, 150, 180 days, or 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 months or greater when measured in a mask efficiency assay. For example, the mask efficiency assay may involve measurement of the affinity of IL12 binding to a cell surface displaying a candidate masking moiety by, for example, FACS. Another non-limiting exemplary assay includes assessing the 45 CYTX-115-PCT 4862-0152WO1 ability of a masking moiety to inhibit IL12 binding to its binding partner at therapeutically relevant concentrations and times. For this second method, an immunosorbant assay to measure the time- dependent binding of proprotein binding to its binding partner has been developed as described in US20200308243, incorporated herein by reference. Half-life extending moieties (EMs) [00132] The activatable IL12 fusion protein or AIC of the present disclosure may include one or more EMs. In one aspect, the EM sterically interferes with binding of the IL12 fusion protein or AIC to its target. [00133] An EM may inhibit or block the activity of the IL12 due to its proximity and comparative size to the IL12. Steric inhibition of the IL12 can be removed by spatially separating the IL12 from the EM, such as by cleaving the IL12 fusion protein or AIC at a site between the EM and the IL12. In one aspect, the EM does not bind specifically to the IL12 fusion protein or AIC. In some aspects, upon cleavage of a CM in the IL12 fusion protein or AIC, the EM does not sterically interfere with binding of the IL12 fusion protein or AIC to the target. Thus, when the CM is cleaved, the EM can dissociate from IL12, and the IL12 can then activate its receptor. In some examples, the EM is selected from the group consisting of an albumin binding peptide, a fibrinogen binding peptide, a fibronectin binding peptide, a hemoglobin binding peptide, a transferrin binding peptide, an immunoglobulin domain binding peptide, and other serum protein binding peptides. In some examples, the EM is a soluble, globular protein. In some examples, the EM is a protein that circulates in the bloodstream. In some examples, the EM is selected from the group consisting of an albumin, a fibrinogen, a fibronectin, a hemoglobin, a transferrin, an immunoglobulin domain, and other serum proteins. In some examples, the EM comprises a polyalkylene glycol polymer (also known as polyalkylene oxides), e.g., a poly(ethylene glycol) (PEG)-containing moiety, hexa-hat GST (glutathione S-transferase) glutathione affinity, Calmodulin-binding peptide (CBP), latency associated protein (LAP), Strep-tag, Cellulose Binding Domain, Maltose Binding Protein, S-Peptide Tag, Chitin Binding Tag, Immuno-reactive Epitopes, Epitope Tags, E2Tag, HA Epitope Tag, Myc Epitope, FLAG Epitope, AU1 and AU5 Epitopes, Glu-Glu Epitope, KT3 Epitope, IRS Epitope, Btag Epitope, Protein Kinase-C Epitope, and VSV Epitope. In some aspects, the EM may contain an alpha- or omega-dihydroxylpoly(ethylene glycol), can also be represented as HO- PEG-OH, where it is understood that the term (“PEG”) or (“-PEG-”) represents the following structural unit: 46 CYTX-115-PCT 4862-0152WO1 —CH2CH2—(CH2CH2O)n—CH2CH2—, where n may range from about 1,000 to about 50,000. PEG may be used as methoxy-PEG-OH, or mPEG, in which one terminus is the relatively inert methoxy group, while the other terminus is a hydroxyl group that is subject to ready chemical modification. Additionally, random or block copolymers of different alkylene oxides (e.g., ethylene oxide and propylene oxide) may be used. [00134] In some aspects, the EM is an albumin binding peptide comprising the amino acid sequence QRLMEDICLPRWGCLWEDDF (SEQ ID NO: 1424). In some aspects, the EM comprises an albumin binding peptide fused to a flexible portion (FP1) having the sequence GSSGGSGGSGGSGGGSGGGSGG (SEQ ID NO: 1425). [00135] In some aspects, one or more EMs include members of a pair, e.g., a dimerization domain (DD), as described herein. In some aspects, one or more EMs include one or more Fc domains, as described herein. In some aspects, AICs include EMs comprising a pair of Fc domains that form a homodimer, i.e., identical Fc domains interact with each other to form a dimer. In some aspects, AICs include EMs comprising Fc domains that form a heterodimer, i.e., a dimer of Fc domains that are not identical in amino acid sequence. In some aspects, an Fc domain comprises an Fc hinge domain, or sequence or truncation variant thereof. For example, for heterodimerization, a knobs- into-holes strategy is used. The basis for creating a knob and a hole in the juxtaposed positions is that the knob and hole interaction will favor heterodimer formation, whereas the knob-knob and the hole-hole interaction will hinder homodimers formation due to the steric clash and deletion of favorable interactions, respectively. [00136] In some aspects, one or more EMs each include a total of about 5 amino acids to about 250 amino acids, about 5 amino acids to about 200 amino acids, about 5 amino acids to about 180 amino acids, about 5 amino acids to about 160 amino acids, about 5 amino acids to about 140 amino acids, about 5 amino acids to about 120 amino acids, about 5 amino acids to about 100 amino acids, about 5 amino acids to about 80 amino acids, about 5 amino acids to about 60 amino acids, about 5 amino acids to about 40 amino acids, about 5 amino acids to about 20 amino acids, about 5 amino acids to about 10 amino acids, about 10 amino acids to about 250 amino acids, about 10 amino acids to about 200 amino acids, about 10 amino acids to about 180 amino acids, about 10 amino acids to about 160 amino acids, about 10 amino acids to about 140 amino acids, about 10 amino acids to about 120 amino acids, about 10 amino acids to about 100 amino acids, about 10 amino acids to about 80 amino acids, about 10 amino acids to about 60 amino acids, 47 CYTX-115-PCT 4862-0152WO1 about 10 amino acids to about 40 amino acids, about 10 amino acids to about 20 amino acids, about 20 amino acids to about 250 amino acids, about 20 amino acids to about 200 amino acids, about 20 amino acids to about 180 amino acids, about 20 amino acids to about 160 amino acids, about 20 amino acids to about 140 amino acids, about 20 amino acids to about 120 amino acids, about 20 amino acids to about 100 amino acids, about 20 amino acids to about 80 amino acids, about 20 amino acids to about 60 amino acids, about 20 amino acids to about 40 amino acids, about 40 amino acids to about 250 amino acids, about 40 amino acids to about 200 amino acids, about 40 amino acids to about 180 amino acids, about 40 amino acids to about 160 amino acids, about 40 amino acids to about 140 amino acids, about 40 amino acids to about 120 amino acids, about 40 amino acids to about 100 amino acids, about 40 amino acids to about 80 amino acids, about 40 amino acids to about 60 amino acids, about 60 amino acids to about 250 amino acids, about 60 amino acids to about 200 amino acids, about 60 amino acids to about 180 amino acids, about 60 amino acids to about 160 amino acids, about 60 amino acids to about 140 amino acids, about 60 amino acids to about 120 amino acids, about 60 amino acids to about 100 amino acids, about 60 amino acids to about 80 amino acids, about 80 amino acids to about 250 amino acids, about 80 amino acids to about 200 amino acids, about 80 amino acids to about 180 amino acids, about 80 amino acids to about 160 amino acids, about 80 amino acids to about 140 amino acids, about 80 amino acids to about 120 amino acids, about 80 amino acids to about 100 amino acids, about 100 amino acids to about 250 amino acids, about 100 amino acids to about 200 amino acids, about 100 amino acids to about 180 amino acids, about 100 amino acids to about 160 amino acids, about 100 amino acids to about 140 amino acids, about 100 amino acids to about 120 amino acids, about 120 amino acids to about 250 amino acids, about 120 amino acids to about 200 amino acids, about 120 amino acids to about 180 amino acids, about 120 amino acids to about 160 amino acids, about 120 amino acids to about 140 amino acids, about 140 amino acids to about 250 amino acids, about 140 amino acids to about 200 amino acids, about 140 amino acids to about 180 amino acids, about 140 amino acids to about 160 amino acids, about 160 amino acids to about 250 amino acids, about 160 amino acids to about 200 amino acids, about 160 amino acids to about 180 amino acids, about 180 amino acids to about 250 amino acids, about 180 amino acids to about 200 amino acids, or about 200 amino acids to about 250 amino acids. [00137] In one aspect, the EM is C-terminal to p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, the EM is C-terminal to p40 subunit of IL12 in the activatable IL12 48 CYTX-115-PCT 4862-0152WO1 fusion protein or AIC. In one aspect, the EM is N-terminal to p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, the EM is N-terminal to p40 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a linker is provided between the EM and the p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a linker is provided between the EM and the p40 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a CM is provided between the EM and the p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a CM is provided between the EM and the p40 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a MM is provided between the EM and the p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a MM is provided between the EM and the p40 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a CM, a linker, and/or a MM is/are provided between the EM and the p35 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, a CM, a linker, and/or a MM is/are provided between the EM and the p40 subunit of IL12 in the activatable IL12 fusion protein or AIC. In one aspect, the EM directly abuts the MM. In one aspect, the EM directly abuts the CM. Dimerization domains (DDs) [00138] The activatable IL12 fusion protein or AIC of the present disclosure may include one or more DDs. Any of a variety of dimerization domains that are known in the art are suitable for use in the practice of the present invention. Suitable DDs include both polymeric (e.g., a synthetic polymer, a polypeptide, a polynucleotide, and the like) and small molecule (non-polymeric moieties having a molecular weight of less than about 1 kDa, and sometimes less than about 800 Daltons) types of moieties. [00139] For example, in some aspects, the DD1 and the DD2 are members of a pair selected from the group of: barnase and barnstar; a PKA and an AKAP; adapter/docking tag molecules based on mutated Rnase I fragments; a pair of antigen-binding domains (e.g., a pair of single domain antibodies); soluble N-ethyl-maleimide sensitive factor attachment protein receptors (SNARE) modules based on interactions of the proteins syntaxin, synaptotagmin, synaptobrevin, and SNAP25; a single domain antibody (sdAb) and corresponding epitope; an antigen-binding domain (e.g., a single chain antibody such as a single chain variable fragment (scFv), a single domain antibody, and the like) and a corresponding epitope; coiled coil polypeptide structures (e.g., Fos- Jun coiled coil structures, acid/base coiled-coil helices, Glu-Lys coiled coil helices, leucine zipper 49 CYTX-115-PCT 4862-0152WO1 structures), small molecule binding pairs such as biotin and avidin or streptavidin, amine/aldehyde, lectin/carbohydrate; a pair of polymers that can bind each other, such as, for example, a pair of sulfur- or thiol-containing polymers (e.g., a pair of Fc domains, a pair of thiolized-human serum albumin polypeptides, and the like); and the like. [00140] In some aspects, the DD1 and DD2 are non-polypeptide polymers. The non-polypeptide polymers may covalently bound to each other. In some examples, the non-polypeptide polymers are a sulfur-containing polymer, e.g., sulfur-containing polyethylene glycol. In such cases, the DD1 and DD2 are covalently bound to each other via one or more disulfide bonds. [00141] When the pair of DD1 and DD2 are members of a pair of epitope and antigen-binding domain, the epitope may be a naturally or non-naturally occurring epitope. Exemplary non- naturally occurring epitopes include, for example, a non-naturally occurring peptide, such as, for example, a poly-His peptide (e.g., a His tag, and the like). [00142] In certain specific embodiments, the DD1 and the DD2 are a pair of Fc domains. As used herein, an “Fc domain” refers to a contiguous amino acid sequence of a portion of a single heavy chain of an immunoglobulin that excludes its variable domains, e.g., the hinge, the CH2-CH3 domains of IgG, IgA, or IgD, or the CH2-CH3-CH4 domains of IgE or IgM and engineered variants thereof. A pair of Fc domains associate together to form an Fc region of an immunoglobulin. [00143] In some aspects, the pair of Fc domains is a pair of human Fc domains (e.g., a pair of wild type human Fc domains). In some aspects, the human Fc domains are human IgG1 Fc domains (e.g., wildtype human IgG1 Fc domains), human IgG2 Fc domains (e.g., wildtype human IgG2 Fc domains), human IgG3 Fc domains (e.g., wildtype human IgG3 Fc domains), or human IgG4 Fc domains (e.g., wildtype human IgG4 Fc domains). In some aspects, the human Fc domains comprise a sequence that is at least 80% identical (e.g., at least 82%, at least 84%, at least 85%, at least 86%, at least 88%, at least 90%, at least 92%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical) to SEQ ID NO: 2. [00144] In some aspects, the pair of Fc domains comprises a knob mutant and a hole mutant of a Fc domain. The knob and hole mutants may interact with each other to facilitate the dimerization. In some aspects, the knob and hole mutants comprises one or more amino acid modifications within the interface between two Fc domains (e.g., in the CH3 domain). In one example, the modifications comprise amino acid substitution T366W and optionally the amino acid substitution S354C in one 50 CYTX-115-PCT 4862-0152WO1 of the antibody heavy chains, and the amino acid substitutions T366S, L368A, Y407V and optionally Y349C in the other one of the antibody heavy chains (numbering according to EU index of Kabat numbering system). Examples of the knob and hole mutants include Fc mutants described in U.S. Pat. Nos. 5,731,168; 7,695,936; and 10,683,368, which are incorporated herein by reference in their entireties. In some aspects, the human Fc domains comprise the mutation N297Q, N297A, or N297G; in some aspects the human Fc domains comprise a mutation at position 234 and/or 235, for example L235E, or L234A and L235A (in IgG1), or F234A and L235A (in IgG4); in some aspects the human Fc domains are IgG2 Fc domains that comprise the mutations V234A, G237A, P238S, H268Q/A, V309L, A330S, or P331S, or a combination thereof (all according to EU numbering). Additional examples of engineered human Fc domains are known to those skilled in the art. Examples of Ig heavy chain constant region amino acids in which mutations in at least one amino acid leads to reduced Fc function include, but are not limited to, mutations in amino acid 228, 233, 234, 235, 236, 237, 239, 252, 254, 256, 265, 270, 297, 318, 320, 322, 327, 329, 330, and 331 of the heavy constant region (according to EU numbering). Examples of combinations of mutated amino acids are also known in the art, such as, but not limited to a combination of mutations in amino acids 234, 235, and 331, such as L234F, L235E, and P331S or a combination of amino acids 318, 320, and 322, such as E318A, K320A, and K322A. [00145] Further examples of engineered Fc domains include F243L/R292P/Y300L/V305I/P396 IgG1; S239D/I332E IgG1; S239D/I332E/A330L IgG1; S298A/E333A/K334A; in one heavy chain, L234Y/L235Q/G236W/S239M/H268D/D270E/S298A IgG1, and in the opposing heavy chain, D270E/K326D, A330M/K334E IgG; G236A/S239D/I332E IgG1; K326W/E333S IgG1; S267E/H268F/S324T IgG1; E345R/E430G/S440Y IgG1; N297A or N297Q or N297G IgG1; L235E IgG1; L234A/L235A IgG1; F234A/L235A IgG4; H268Q/V309L/A330S/P331S IgG2; V234A/G237A/P238S/H268A/V309L/A330S/P331S IgG2; M252Y/S254T/T256E IgG1; M428L/N434S IgG1; S267E/L328F IgG1; N325S/L328F IgG1, and the like. In some aspects, the engineered Fc domain comprises one or more substitutions selected from the group consisting of N297A IgG1, N297Q IgG1, and S228P IgG4. [00146] In some aspects, the dimerization domain is an IgG Fc region wherein the upper hinge residues have been deleted. For example, the Fc is a variant wherein N-terminal sequences EPKSCDKTHT (SEQ ID NO: 55), ERK, ELKTPLGDTTHT (SEQ ID NO: 56), or ESKYGPP (SEQ ID NO: 57) have been deleted. 51 CYTX-115-PCT 4862-0152WO1 [00147] In some aspects, the DD, or the DD1 and/or DD2, can further include a serum half-life extending moiety (e.g., polypeptides that bind serum proteins, such as immunoglobulin (e.g., IgG) or serum albumin (e.g., human serum albumin (I)). Examples of half-life extending moieties include hexa-hat GST (glutathione S-transferase) glutathione affinity, Calmodulin-binding peptide (CBP), Strep-tag, Cellulose Binding Domain, Maltose Binding Protein, S-Peptide Tag, Chitin Binding Tag, Immuno-reactive Epitopes, Epitope Tags, E2Tag, HA Epitope Tag, Myc Epitope, FLAG Epitope, AU1 and AU5 Epitopes, Glu-Glu Epitope, KT3 Epitope, IRS Epitope, Btag Epitope, Protein Kinase-C Epitope, and VSV Epitope. [00148] In some aspects, DD1 and/or DD2 each include a total of about 5 amino acids to about 350 amino acids, about 5 amino acids to about 250 amino acids, about 5 amino acids to about 200 amino acids, about 5 amino acids to about 180 amino acids, about 5 amino acids to about 160 amino acids, about 5 amino acids to about 140 amino acids, about 5 amino acids to about 120 amino acids, about 5 amino acids to about 100 amino acids, about 5 amino acids to about 80 amino acids, about 5 amino acids to about 60 amino acids, about 5 amino acids to about 40 amino acids, about 5 amino acids to about 20 amino acids, about 5 amino acids to about 10 amino acids, about 10 amino acids to about 350 amino acids, about 10 amino acids to about 250 amino acids, about 10 amino acids to about 200 amino acids, about 10 amino acids to about 180 amino acids, about 10 amino acids to about 160 amino acids, about 10 amino acids to about 140 amino acids, about 10 amino acids to about 120 amino acids, about 10 amino acids to about 100 amino acids, about 10 amino acids to about 80 amino acids, about 10 amino acids to about 60 amino acids, about 10 amino acids to about 40 amino acids, about 10 amino acids to about 20 amino acids, about 20 amino acids to about 350 amino acids, about 20 amino acids to about 250 amino acids, about 20 amino acids to about 200 amino acids, about 20 amino acids to about 180 amino acids, about 20 amino acids to about 160 amino acids, about 20 amino acids to about 140 amino acids, about 20 amino acids to about 120 amino acids, about 20 amino acids to about 100 amino acids, about 20 amino acids to about 80 amino acids, about 20 amino acids to about 60 amino acids, about 20 amino acids to about 40 amino acids, about 40 amino acids to about 350 amino acids, about 40 amino acids to about 250 amino acids, about 40 amino acids to about 200 amino acids, about 40 amino acids to about 180 amino acids, about 40 amino acids to about 160 amino acids, about 40 amino acids to about 140 amino acids, about 40 amino acids to about 120 amino acids, about 40 amino acids to about 100 amino acids, about 40 amino acids to about 80 amino acids, about 40 52 CYTX-115-PCT 4862-0152WO1 amino acids to about 60 amino acids, about 60 amino acids to about 350 amino acids, about 60 amino acids to about 250 amino acids, about 60 amino acids to about 200 amino acids, about 60 amino acids to about 180 amino acids, about 60 amino acids to about 160 amino acids, about 60 amino acids to about 140 amino acids, about 60 amino acids to about 120 amino acids, about 60 amino acids to about 100 amino acids, about 60 amino acids to about 80 amino acids, about 80 amino acids to about 350 amino acids, about 80 amino acids to about 250 amino acids, about 80 amino acids to about 200 amino acids, about 80 amino acids to about 180 amino acids, about 80 amino acids to about 160 amino acids, about 80 amino acids to about 140 amino acids, about 80 amino acids to about 120 amino acids, about 80 amino acids to about 100 amino acids, about 100 amino acids to about 350 amino acids, about 100 amino acids to about 250 amino acids, about 100 amino acids to about 200 amino acids, about 100 amino acids to about 180 amino acids, about 100 amino acids to about 160 amino acids, about 100 amino acids to about 140 amino acids, about 100 amino acids to about 120 amino acids, about 120 amino acids to about 350 amino acids, about 120 amino acids to about 250 amino acids, about 120 amino acids to about 200 amino acids, about 120 amino acids to about 180 amino acids, about 120 amino acids to about 160 amino acids, about 120 amino acids to about 140 amino acids, about 140 amino acids to about 350 amino acids, about 140 amino acids to about 250 amino acids, about 140 amino acids to about 200 amino acids, about 140 amino acids to about 180 amino acids, about 140 amino acids to about 160 amino acids, about 160 amino acids to about 350 amino acids, about 160 amino acids to about 250 amino acids, about 160 amino acids to about 200 amino acids, about 160 amino acids to about 180 amino acids, about 180 amino acids to about 250 amino acids, about 180 amino acids to about 200 amino acids, about 200 amino acids to about 250 amino acids, about 210 to about 220 amino acids, about 215 to about 225 amino acids, about 215 to about 220 amino acids, about 217 to about 200 amino acids, or about 218 to about 200 amino acids. In some aspects, DD1 and DD2 are each an Fc domain that comprises a portion of the hinge region that includes two cysteine residues, a CH2 domain, and a CH3 domain. In some aspects, DD1 and DD2 are each an Fc domain whose N-terminus is thefirst cysteine residue in the hinge region reading in the N- to C- direction (e.g., Cysteine 226 of human IgG1 or IgG4, using EU numbering). [00149] In some aspects, thefirst monomer and/or the second monomer can each include a total of about 150 amino acids to about 800 amino acids, about 150 amino acids to about 750 amino acids, about 150 amino acids to about 700 amino acids, about 150 amino acids to about 650 amino 53 CYTX-115-PCT 4862-0152WO1 acids, about 150 amino acids to about 600 amino acids, about 150 amino acids to about 550 amino acids, about 150 amino acids to about 500 amino acids, about 150 amino acids to about 450 amino acids, about 150 amino acids to about 400 amino acids, about 150 amino acids to about 350 amino acids, about 150 amino acids to about 300 amino acids, about 150 amino acids to about 250 amino acids, about 150 amino acids to about 200 amino acids, about 200 amino acids to about 800 amino acids, about 200 amino acids to about 750 amino acids, about 200 amino acids to about 700 amino acids, about 200 amino acids to about 650 amino acids, about 200 amino acids to about 600 amino acids, about 200 amino acids to about 550 amino acids, about 200 amino acids to about 500 amino acids, about 200 amino acids to about 450 amino acids, about 200 amino acids to about 400 amino acids, about 200 amino acids to about 350 amino acids, about 200 amino acids to about 300 amino acids, about 200 amino acids to about 250 amino acids, about 250 amino acids to about 800 amino acids, about 250 amino acids to about 750 amino acids, about 250 amino acids to about 700 amino acids, about 250 amino acids to about 650 amino acids, about 250 amino acids to about 600 amino acids, about 250 amino acids to about 550 amino acids, about 250 amino acids to about 500 amino acids, about 250 amino acids to about 450 amino acids, about 250 amino acids to about 400 amino acids, about 250 amino acids to about 350 amino acids, about 250 amino acids to about 300 amino acids, about 300 amino acids to about 800 amino acids, about 300 amino acids to about 750 amino acids, about 300 amino acids to about 700 amino acids, about 300 amino acids to about 650 amino acids, about 300 amino acids to about 600 amino acids, about 300 amino acids to about 550 amino acids, about 300 amino acids to about 500 amino acids, about 300 amino acids to about 450 amino acids, about 300 amino acids to about 400 amino acids, about 300 amino acids to about 350 amino acids, about 350 amino acids to about 800 amino acids, about 350 amino acids to about 750 amino acids, about 350 amino acids to about 700 amino acids, about 350 amino acids to about 650 amino acids, about 350 amino acids to about 600 amino acids, about 350 amino acids to about 550 amino acids, about 350 amino acids to about 500 amino acids, about 350 amino acids to about 450 amino acids, about 350 amino acids to about 400 amino acids, about 400 amino acids to about 800 amino acids, about 400 amino acids to about 750 amino acids, about 400 amino acids to about 700 amino acids, about 400 amino acids to about 650 amino acids, about 400 amino acids to about 600 amino acids, about 400 amino acids to about 550 amino acids, about 400 amino acids to about 500 amino acids, about 400 amino acids to about 450 amino acids, about 450 amino acids to about 800 amino acids, about 450 amino acids to about 750 amino acids, about 450 amino acids to about 700 amino 54 CYTX-115-PCT 4862-0152WO1 acids, about 450 amino acids to about 650 amino acids, about 450 amino acids to about 600 amino acids, about 450 amino acids to about 550 amino acids, about 450 amino acids to about 500 amino acids, about 500 amino acids to about 800 amino acids, about 500 amino acids to about 750 amino acids, about 500 amino acids to about 700 amino acids, about 500 amino acids to about 650 amino acids, about 500 amino acids to about 600 amino acids, about 500 amino acids to about 550 amino acids, about 550 amino acids to about 800 amino acids, about 550 amino acids to about 750 amino acids, about 550 amino acids to about 700 amino acids, about 550 amino acids to about 650 amino acids, about 550 amino acids to about 600 amino acids, about 600 amino acids to about 800 amino acids, about 600 amino acids to about 750 amino acids, about 600 amino acids to about 700 amino acids, about 600 amino acids to about 650 amino acids, about 650 amino acids to about 800 amino acids, about 650 amino acids to about 750 amino acids, about 650 amino acids to about 700 amino acids, about 700 amino acids to about 800 amino acids, about 700 amino acids to about 750 amino acids, or about 750 amino acids to about 800 amino acids. [00150] In some aspects, the DD comprises an IgG Fc with a knob mutation, comprising the sequence: DSTHTCPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVD GVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPASIEKTISK AKGQPREPQVYTLPPCRDELTKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPP VLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO: 1505). [00151] In some aspects, the DD comprises a human IgG Fc with a knob mutation, comprising the sequence: CPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEV HNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQP REPQVYTLPPCQEEMTKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLG (SEQ ID NO: 307). [00152] In some aspects, the DD comprises an IgG Fc with a hole mutation comprising the sequence: DSTHTCPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVD GVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPASIEKTISK AKGQPREPQVCTLPPSRDELTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPV 55 CYTX-115-PCT 4862-0152WO1 LDSDGSFFLVSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO: 1506). [00153] In some aspects, the DD comprises a human IgG Fc with a hole mutation comprising the sequence: CPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEV HNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQP REPQVCTLPPSQEEMTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDG SFFLVSRLTVDKSRWQEGNVFSCSVMHEALHNRFTQKSLSLSLG (SEQ ID NO: 308). [00154] In some aspects, the DD comprises a human IgG4 variant (S228P) with a truncated hinge region comprising the sequence: CPPCPAPEFLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEV HNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQP REPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDG SFFLYSRLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLS (SEQ ID NO: 310). In some aspects, the DD comprises a human IgG4 variant (S228P) with a full hinge region comprising the sequence: ESKYGPPCPPCPAPEFLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWY VDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTIS KAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPP VLDSDGSFFLYSRLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLS (SEQ ID NO: 311). [00155] In some aspects, the DD comprises a Human IgG1 sequence comprising: ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGG PSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQY NSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSR EEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDK SRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG* (SEQ ID NO: 314), which may further comprise a lysine residue (K) at the C-terminus. [00156] In some aspects, the DD comprises a human IgG2 sequence comprising: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS 56 CYTX-115-PCT 4862-0152WO1 GLYSLSSVVTVPSSNFGTQTYTCNVDHKPSNTKVDKTVERKCCVECPPCPAPPVAGPSV FLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVQFNWYVDGVEVHNAKTKPREEQFNST FRVVSVLTVVHQDWLNGKEYKCKVSNKGLPAPIEKTISKTKGQPREPQVYTLPPSREEM TKNQVSLTCLVKGFYPSDISVEWESNGQPENNYKTTPPMLDSDGSFFLYSKLTVDKSRW QQGNVFSCSVMHEALHNHYTQKSLSLSPG* (SEQ ID NO: 315), which may further comprise a lysine residue (K) at the C-terminus. [00157] In some aspects, the DD comprises a human IgG3 sequence comprising: ASTKGPSVFPLAPCSRSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTQTYTCNVNHKPSNTKVDKRVELKTPLGDTTHTCPRCPEPKSC DTPPPCPRCPEPKSCDTPPPCPRCPEPKSCDTPPPCPRCPAPELLGGPSVFLFPPKPKDTLMI SRTPEVTCVVVDVSHEDPEVQFKWYVDGVEVHNAKTKPREEQYNSTFRVVSVLTVLHQ DWLNGKEYKCKVSNKALPAPIEKTISKTKGQPREPQVYTLPPSREEMTKNQVSLTCLVK GFYPSDIAVEWESSGQPENNYNTTPPMLDSDGSFFLYSKLTVDKSRWQQGNIFSCSVMH EALHNRFTQKSLSLSPG* (SEQ ID NO: 316), which may further comprise a lysine residue (K) at the C-terminus. [00158] In some aspects, the DD comprises a human IgG4 sequence comprising: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCPSCPAPEFLGGPSV FLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNST YRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEM TKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRW QEGNVFSCSVMHEALHNHYTQKSLSLSLG* (SEQ ID NO: 317), which may further comprise a lysine residue (K) at the C-terminus. Cleavable moieties (CMs) [00159] As described herein, activatable IL12 fusion proteins or AICs comprise one or more CMs. A CM may be positioned between two components in an activatable IL12 fusion protein or AIC, e.g., between an IL12 and an MM, between an IL12 and a DD, and/or between an IL12 and another component in the activatable IL12 fusion protein or the AIC. In some aspects, an MM is coupled with an IL12 via a CM, i.e., the CM is positioned between the IL12 and the MM. [00160] In some aspects, a CM is positioned between an MM and an IL12, either directly or indirectly (e.g., via a linker). In some aspects, a CM is positioned between the IL12 and a DD, 57 CYTX-115-PCT 4862-0152WO1 either directly or indirectly (e.g., via a linker). In some aspects, the CM is positioned within the MM. [00161] Peptide or polypeptide sequences comprising any of a variety of protease substrate sequences may be employed as a CM in the activatable IL12 fusion proteins or AICs of the present disclosure. In some aspects, the CM comprises substrate(s) for two or more proteases. In certain aspects, the CM comprises a substrate for a protease that is upregulated during a disease condition, e.g., in diseased tissue. In some aspects, the CMs herein comprise substrates for proteases that have been reported in a cancer, or in a number of cancers. See, e.g., La Roca et al., British J. Cancer 90(7):1414-1421, 2004. Substrates suitable for use in the CM component employed herein include those which are more prevalently found in cancerous cells and tissue. Thus, in certain embodiments, a CM comprises a substrate for a protease that is more prevalently found in diseased tissue associated with a cancer. In some aspects, the cancer is selected from the group of gastric cancer, breast cancer, osteosarcoma, and esophageal cancer. In some aspects, the cancer is breast cancer. In some aspects, the cancer is a HER2-positive cancer. In some aspects, the cancer is Kaposi sarcoma, hairy cell leukemia, chronic myeloid leukemia (CML), follicular lymphoma, renal cell cancer (RCC), melanoma, neuroblastoma, basal cell carcinoma, cutaneous T-cell lymphoma, nasopharyngeal adenocarcinoma, breast cancer, ovarian cancer, bladder cancer, BCG- resistant non-muscle invasive bladder cancer (NMIBC), endometrial cancer, pancreatic cancer, non-small cell lung cancer (NSCLC), colorectal cancer, esophageal cancer, gallbladder cancer, glioma, head and neck carcinoma, uterine cancer, cervical cancer, or testicular cancer, and the like. In some of the above-described embodiments, the CM components comprise substrates for protease(s) that is/are more prevalent in tumor tissue. For example, the protease(s) may be produced by a tumor in a subject. [00162] Suitable CMs for use herein include any of the protease substrates that are known the art. In some examples, the CM may comprise a substrate of a serine protease (e.g., u-type plasminogen activator, also known as “uPA” or urokinase), a matriptase (also referred to herein as MT-SP1 or MTSP1). In some examples, the CM may comprise a substrate of a matrix metalloprotease (MMP). In some examples, the CM may comprise a substrate of cysteine protease (CP) (e.g., legumain). [00163] In some aspects, the CM may comprise a substrate for a disintegrin and a metalloproteinase (ADAM) or a disintegrin and a metalloproteinase with a thrombospondin motifs (ADAMTS) (e.g., ADAM8, ADAM9, ADAM10, ADAM12, ADAM15, ADAM17/TACE, 58 CYTX-115-PCT 4862-0152WO1 ADEMDEC1, ADAMTS1, ADAMTS4, ADAMTS5), an aspartate protease (e.g. BACE, Renin), an aspartic cathepsin (e.g., Cathepsin D, Cathepsin E), Caspase (e.g., Caspase 1, Caspase 2, Caspase 3, Caspase 4, Caspase 5, Caspase 6, Caspase 7, Caspase 8, Caspase 9, Caspase 10, Caspase 14), cysteine cathepsin (e.g., Cathepsin A, Cathepsin B, Cathepsin C, Cathepsin G, Cathepsin K, Cathepsin L, Cathepsin S, Cathepsin V/L2, Cathepsin X/Z/P), a cysteine proteinase (e.g., Cruzipain, Legumain, Otubain-2), a Chymase, DESC1, DPP-4, FAP, an Elastase, FVIIa, FiXA, Fxa, FXIa, FXIIa, Granzyme B, Guanidinobenzoatase, Hepsin, HtrA1, Human a Neutrophil Elastase, a KLK (e.g., KLK4, KLK5, KLK6, KLK7, KLK8, KLK10, KLK11, KLK13, KLK14), a metallo proteinase (e.g., Meprin, Neprilysin, PSMA, BMP-1), Lactoferrin, Marapsin, Matriptase-2, , MT-SP1/Matriptase, NS3/4A, PACE4, Plasmin, PSA, an MMP (e.g., MMP1, MMP2, MMP3, MMP7, MMP8, MMP9, MMP10, MMP11, MMP12, MMP13, MMP14, MMP15, MMP16, MMP17, MMP19, MMP20, MMP23, MMP24, MMP26, MMP27), TMPRSS2, TMPRSS3, TMPRSS4, tPA, Thrombin, Tryptase, and uPA. [00164] In some aspects, the protease substrate in the CM may comprise a polypeptide sequence that is not substantially identical (e.g., no more than 90%, 80%, 70%, 60%, or 50% identical) to any polypeptide sequence that is naturally cleaved by the same protease. [00165] In some aspects, CM comprises or consists of a sequence selected from SEQ ID NOs: 58- 60, 101-242, 244-282, 318-1354, and 1388-1423. In some aspects, CM comprises PXGL, wherein X is any amino acid. In some aspects, CM comprises GRS, PRS, SRS, or RS. [00166] In some aspects, CM comprises a sequence selected from ISSGLLSS (SEQ ID NO: 144), LSGRSNI (SEQ ID NO: 246), DHQSRSGPWGLL (SEQ ID NO: 428), PWGLHQSRS (SEQ ID NO: 649), PWGLSGRS (SEQ ID NO: 805), LSGRSPWGL (SEQ ID NO: 962), or DHQSRS (SEQ ID NO: 1278). [00167] In some aspects, CM comprises or consists of an amino acid sequence according to SEQ ID NO: 1388, SEQ ID NO: 1389, SEQ ID NO: 1394, SEQ ID NO: 1399, SEQ ID NO: 1404, SEQ ID NO: 1409, SEQ ID NO: 1414, or SEQ ID NO: 1419. [00168] In some aspects, the CM comprises a sequence selected from: SEQ ID NO: 1390, SEQ ID NO: 1391, SEQ ID NO: 1392, SEQ ID NO: 1393, SEQ ID NO: 1395, SEQ ID NO: 1396, SEQ ID NO: 1397, SEQ ID NO: 1398, SEQ ID NO: 1400, SEQ ID NO: 1401, SEQ ID NO: 1402, SEQ ID NO: 1403, SEQ ID NO: 1405, SEQ ID NO: 1406, SEQ ID NO: 1407, SEQ ID NO: 1408, SEQ ID NO: 1410, SEQ ID NO: 1411, SEQ ID NO: 1412, SEQ ID NO: 1413, 59 CYTX-115-PCT 4862-0152WO1 SEQ ID NO: 1415, SEQ ID NO: 1416, SEQ ID NO: 1417, SEQ ID NO: 1418, SEQ ID NO: 1420, SEQ ID NO: 1421, SEQ ID NO: 1422, or SEQ ID NO: 1423. In cases where the cleavable polypeptide comprises more than one CM, the CMs each independently comprise one of the foregoing sequences. [00169] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1390, SEQ ID NO: 1391, SEQ ID NO: 1392, or SEQ ID NO: 1393. [00170] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1395, SEQ ID NO: 1396, SEQ ID NO: 1397, or SEQ ID NO: 1398. [00171] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1400, SEQ ID NO: 1401, SEQ ID NO: 1402, or SEQ ID NO: 1403. [00172] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1405, SEQ ID NO: 1406, SEQ ID NO: 1407, or SEQ ID NO: 1408. [00173] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1410, SEQ ID NO: 1411, SEQ ID NO: 1412, or SEQ ID NO: 1413. [00174] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1415, SEQ ID NO: 1416, SEQ ID NO: 1417, or SEQ ID NO: 1418. [00175] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1420, SEQ ID NO: 1421, SEQ ID NO: 1422, or SEQ ID NO: 1423. [00176] In certain aspects, the CM comprises a sequence selected from: SEQ ID NO: 1390, SEQ ID NO: 1395, SEQ ID NO: 1400, SEQ ID NO: 1405, SEQ ID NO: 1410, SEQ ID NO: 1415, or SEQ ID NO: 1420. [00177] In some aspects, CM comprises or consists of a sequence of SEQ ID NO: 5 or SEQ ID NO: 59. In some aspects, the CM comprises or consists of a sequence of encompassed by the consensus of sequence of any one of SEQ ID NOs: 317–327, 329–335, 340–347, 352–363, 371– 378, 394–401, 410–419, 425–433, 436–449, 453–456, 458–469, 473, 475–482, 485–495 disclosed in WO2015048329, which is incorporated by reference herein in its entirety, and SEQ ID NOs: 1– 162, 268–306 disclosed in WO2015116933, which is incorporated by reference herein in its entirety. [00178] In some aspects, the CM comprises or consists of a sequence of any one of SEQ ID NOs: 14–52, 126–154. 159, 315–316, 328, 336–339, 348–351, 364–370, 379–393, 402–409, 420–424, 434–435, 450–452, 457, 470–472, 474, 483, 484 disclosed in WO2015048329, SEQ ID NOs: 163– 60 CYTX-115-PCT 4862-0152WO1 267, 307–384, 402–445, 665–683 disclosed in WO2015116933, SEQ ID NOs: 20–21, 411, 480– 482, 351–369, 18, 71, 370–380, 412–415, 468, 547–554, 319–346 disclosed in WO2016118629, which is incorporated by reference herein in its entirety, and SEQ ID NOs: 1–16, 50–56, 60–63, 20, 70–76, 78–115, 120–128, 130–132, 135–140, 141, 152, 21–23, 17–19, 25–43 disclosed in WO2020118109, which is incorporated by reference herein in its entirety. In some examples, the CM of a cysteine protease comprises or consists of the sequence of AAN, SAN, or SEQ ID NO: 60. Examples of CMs also include those in the sequence listing filed herewith, and those described in WO 2010/081173, WO2021207669, WO2021207657, WO2021142029, WO2021061867, WO2020252349, WO2020252358, WO2020236679, WO2020176672, WO2020118109, WO2020092881, WO2020086665, WO2019213444, WO2019183218, WO2019173771, WO2019165143, WO2019075405, WO2019046652, WO2019018828, WO2019014586, WO2018222949, WO2018165619, WO2018085555, WO2017011580, WO2016179335, WO2016179285, WO2016179257, WO2016149201, WO2024/030843, WO2024/030845, WO2024/030847, WO2024/030858, WO2024/030850, and WO2016014974, which are incorporated herein by reference in their entireties. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 1354, SEQ ID NO: 805, SEQ ID NO: 1278, and SEQ ID NO: 144. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 318-1347 and 1388-1423. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 318-331. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 332-400. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 401-794. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 795-1274. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1275-1347. In some aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1388-1423. Exemplary CMs that are suitable for use in the AICs described herein, include substrates for Pro-urokinase (e.g., SEQ ID NOs: 101-102), TGFβ (e.g., SEQ ID NO: 103), plasminogen (e.g., SEQ ID NO: 104), Staphylokinase (e.g., SEQ ID NOs: 105-106). [00179] In some aspects, the CM comprises or consists of a combination of the example sequences discussed above, a C-terminal truncation variant of the example sequences discussed above, or an 61 CYTX-115-PCT 4862-0152WO1 N-terminal truncation variant of the example sequences discussed above. Truncation variants of the aforementioned amino acid sequences that are suitable for use in a CM are any that retain the recognition site for the corresponding protease. These include C-terminal and/or N-terminal truncation variants comprising at least 3 contiguous amino acids of the above-described amino acid sequences, or at least 4, or at least 5, or at least 6, or at least 7 amino acids of the foregoing amino acid sequences that retain a recognition site for a protease. In certain embodiments, the truncation variant of the above-described amino acid sequences is an amino acid sequence corresponding to any of the above, but that is C- and/or N-terminally truncated by 1 to about 10 amino acids, 1 to about 9 amino acids, 1 to about 8 amino acids, 1 to about 7 amino acids, 1 to about 6 amino acids, 1 to about 5 amino acids, 1 to about 4 amino acids, or 1 to about 3 amino acids, and which: (1) has at least three amino acid residues; and (2) retains a recognition site for a protease. In some of the foregoing embodiments, the truncated CM is an N-terminally truncated CM. In some aspects, the truncated CM is a C-terminally truncated CM. In some aspects, the truncated C is a C- and an N-terminally truncated CM. [00180] In some aspects, the CM may comprise a total of 3 amino acids to 25 amino acids. In some aspects, the CM may comprise a total of 3 to 25, 3 to 20, 3 to 15, 3 to 10, 3 to 5, 5 to 25, 5 to 20, 5 to 15, 5 to 10, 10 to 25, 10 to 20, 10 to 15, 15 to 25, 15 to 20, or 20 to 25 amino acids. [00181] In some aspects, the CM is specifically cleaved by at least a protease at a rate of about 0.001–1500×104 M-1s-1 or at least 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2.5, 5, 7.5, 10, 15, 20, 25, 50, 75, 100, 125, 150, 200, 250, 500, 750, 1000, 1250, or 1500×104 M-1s-1. The rate may be measured as substrate cleavage kinetics (kcat/Km) as disclosed in WO2016118629. [00182] In some aspects of any of the activatable IL12 fusion proteins or AICs described herein, the CM comprise a total of about 3 amino acids to about 25 amino acids. In some aspects, the CM comprise a total of about 3 amino acids to about 25 amino acids, about 3 amino acids to about 20 amino acids, about 3 amino acids to about 15 amino acids, about 3 amino acids to about 10 amino acids, about 3 amino acids to about 5 amino acids, about 5 amino acids to about 25 amino acids, about 5 amino acids to about 20 amino acids, about 5 amino acids to about 15 amino acids, about 5 amino acids to about 10 amino acids, about 10 amino acids to about 25 amino acids, about 10 amino acids to about 20 amino acids, about 10 amino acids to about 15 amino acids, about 15 amino acids to about 25 amino acids, about 15 amino acids to about 20 amino acids, or about 20 amino acids to about 25 amino acids. 62 CYTX-115-PCT 4862-0152WO1 [00183] In some aspects, the activatable IL12 fusion protein or AIC comprises multiple CMs that comprise substrates for different proteases. In some aspects, the CM1 and the CM2 in a dimer comprise substrates for different proteases. In some aspects, the CM1 and the CM2 in a dimer comprise substrates for the same protease. Linkers [00184] As described herein, in various aspects the DD and IL12 and/or the IL12 and MM structural elements in the activatable IL12 fusion proteins or AICs are linked via one or more linkers. In some aspects, the linker comprises, for example, a CM, a flexible linker, and the like, or any combination thereof. In some aspects, the linker comprises a CM. Exemplary CMs are described in more detail herein. In other aspects, the linker comprises a flexible linker. In further aspects the linker comprises a CM and at least one flexible linker. In further aspects the linker comprises a CM and at least one flexible linker N-terminally adjacent to the CM and at least one flexible linker C-terminally adjacent to the CM. The term “flexible linker” is used herein to refer to a polypeptide that facilitates formation and maintenance of a structure in the activatable IL-12 fusion protein or AIC in circumstances where such structure would otherwise be conformationally constrained, and where inclusion of such flexible linker imparts sufficient flexibility to facilitate the inhibition of binding of a binding partner (e.g., an IL12 receptor) and/or cleavage of a CM by a protease. [00185] An activatable IL12 fusion protein or AIC may comprise one or more additional components including one or more linkers, and the like. In some aspects, thefirst polypeptide can include a linker disposed between IL12 and the CM. In some aspects, IL12 directly abuts the CM. According to any one or combination of aspects disclosed herein the DD1 of the first polypeptide, the DD2 of the second polypeptide, or both, may be linked to another component, for example, a CM, an MM, or an IL12 subunit (e.g., p35, p40, or both, and when both are present p35 and p40 may be in either order from N-terminus to C-terminus) by a linker. In some aspects, the DD1 and the DD2 comprise an Fc domain. In some aspects, the linker comprises a portion of an Fc hinge region, e.g., the portion of an Fc hinge region that is N-terminal of the first cysteine (from N- to C-terminus) in the Fc hinge region (e.g., native Fc hinge region or sequence or truncation variant thereof). Illustrative Fc hinge domains include, for example, an IgG1 hinge (SEQ ID NO: 73 PKSCDKTHTCPPCPAPELLG and the like), truncated IgG1 hinge (e.g., SEQ ID NO: 1730 DKTHTCPPCPAPELLG and the like), an IgG4 hinge (e.g., SEQ ID NO: 74 63 CYTX-115-PCT 4862-0152WO1 SKYGPPCPPCPAPEFLG; SEQ ID NO: 1731 ESKYGPPCPPCPAPEFLG, and the like), a truncated IgG4 hinge (e.g., SEQ ID NO: 1732 GPPCPPCPAPEFLG, and the like). For example, in some embodiments, the linker comprises the amino acid sequence PKSCDKTHT (SEQ ID NO: 1733), or a sequence or truncation variant thereof. In other embodiments, the linker comprises the amino acid sequence DKTHT (SEQ ID NO: 1734) or sequence or truncation variant thereof. In certain embodiments, the linker comprises the amino acid sequence SKYGPP (SEQ ID NO: 1735) or sequence or truncation variant thereof, such as for example, the amino acid sequence GPP. [00186] In some aspects, thefirst polypeptide can include a linker disposed between the DD1 and the CM1. In some aspects, the DD1 and the CM1 directly abut each other in thefirst polypeptide. In some aspects, the linker has a total length of 1 amino acid to about 15 amino acids. In some aspects, the CM1 and the DD1 directly abut each other in thefirst polypeptide. In some aspects, the CM1 and any linkers disposed between the CM1 and DD1 have a combined total length of 3 to 30, 3 to 25, or 3 to 23, or 3 to 20, or 3 to 18, 3 to 15 amino acids, or 3 to 10 amino acids, or 3 to 7 amino acids. [00187] In some aspects, the second polypeptide comprises a linker disposed between the DD2 and the CM2. In some aspects, the DD2 and the CM2 directly abut each other in the second polypeptide. In some aspects, the linker has a total length of 1 amino acid to about 15 amino acids. In some aspects, the linker comprises a sequence of G; GG; or GGGS (SEQ ID NO: 61). In some aspects, the CM2 (e.g., any of the cleavable moieties described herein) and the DD2 (e.g., any of the DDs described herein) directly abut each other in the second polypeptide. In some aspects, the CM2 and any linkers disposed between the CM2 and DD2 have a combined total length of 3 to 30, 3 to 25, or 3 to 23, or 3 to 20, or 3 to 18, 3 to 15 amino acids, or 3 to 10 amino acids, or 3 to 7 amino acids. [00188] In some aspects, one or moreflexible linkers are introduced into the activable IL12 fusion protein or AIC to provideflexibility at one or more of the junctions between domains, between moieties, between moieties and domains, or at any other junctions where a linker would be beneficial. In some aspects, where the activable IL12 fusion protein or AIC is provided as a conformationally constrained polypeptide or construct, aflexible linker is inserted to facilitate formation and maintenance of a structure in the activable IL12 fusion protein or AIC. Any of the linkers described herein can provide the desiredflexibility to facilitate the inhibition of the binding of a binding partner (e.g., an IL12 receptor), or to facilitate cleavage of a CM by a protease. In 64 CYTX-115-PCT 4862-0152WO1 some aspects, linkers are included in the activable IL12 fusion protein or AIC that are all or partiallyflexible, such that the linker can include aflexible linker as well as one or more portions that confer lessflexible structure to provide for a desired activable IL12 fusion protein or AIC three-dimensional structure. Some linkers may include cysteine residues, which may form disulfide bonds and reduceflexibility of the construct. In some aspects, reducing the length of the linkers reduces the activity of the mature IL12 in the activable IL12 fusion protein or AIC. In most instances, linker length is determined by counting, in a N- to C-terminal direction, the number of amino acids from the N-terminus of the linker adjacent to the C-terminal amino acid of the preceding component, to the C-terminus of the linker adjacent to the N-terminal amino acid of the following component (i.e., where the linker length does not include either the C-terminal amino acid of the preceding component or the N-terminal amino acid of the following component). In embodiments in which a linker is employed at the N-terminus of a DD that comprises an Fc domain, linker length is determined by counting the number of amino acids from the N-terminus of the linker adjacent to the C-terminal amino acid of the preceding component to C-terminus of the linker adjacent to thefirst cysteine of an Fc hinge region (i.e., where the linker length does not include the C-terminal amino acid of the preceding component or thefirst cysteine of the Fc hinge region). When the DD comprises an Fc hinge region that has amino acid residues prior to the first cysteine of the Fc hinge region, that portion of the Fc hinge region is considered a linker and is included in the computation of linker length. [00189] In some aspects of any of the activable IL12 fusion proteins or AICs described herein, a linker includes a total of about 1 amino acid to about 25 amino acids (e.g., about 1 amino acid to about 24 amino acids, about 1 amino acid to about 22 amino acids, about 1 amino acid to about 20 amino acids, about 1 amino acid to about 18 amino acids, about 1 amino acid to about 16 amino acids, about 1 amino acid to about 15 amino acids, about 1 amino acid to about 14 amino acids, about 1 amino acid to about 12 amino acids, about 1 amino acid to about 10 amino acids, about 1 amino acid to about 8 amino acids, about 1 amino acid to about 6 amino acids, about 1 amino acid to about 5 amino acids, about 1 amino acid to about 4 amino acids, about 1 amino acid to about 3 amino acids, about 1 amino acid to about 2 amino acids, about 2 amino acids to about 25 amino acids, about 2 amino acids to about 24 amino acids, about 2 amino acids to about 22 amino acids, about 2 amino acids to about 20 amino acids, about 2 amino acids to about 18 amino acids, about 2 amino acids to about 16 amino acids, about 2 amino acids to about 15 amino acids, about 2 amino 65 CYTX-115-PCT 4862-0152WO1 acids to about 14 amino acids, about 2 amino acids to about 12 amino acids, about 2 amino acids to about 10 amino acids, about 2 amino acids to about 8 amino acids, about 2 amino acids to about 6 amino acids, about 2 amino acids to about 5 amino acids, about 2 amino acids to about 4 amino acids, about 2 amino acids to about 3 amino acids, about 4 amino acids to about 25 amino acids, about 4 amino acids to about 24 amino acids, about 4 amino acids to about 22 amino acids, about 4 amino acids to about 20 amino acids, about 4 amino acids to about 18 amino acids, about 4 amino acids to about 16 amino acids, about 4 amino acids to about 15 amino acids, about 4 amino acids to about 14 amino acids, about 4 amino acids to about 12 amino acids, about 4 amino acids to about 10 amino acids, about 4 amino acids to about 8 amino acids, about 4 amino acids to about 6 amino acids, about 4 amino acids to about 5 amino acids, about 5 amino acids to about 25 amino acids, about 5 amino acids to about 24 amino acids, about 5 amino acids to about 22 amino acids, about 5 amino acids to about 20 amino acids, about 5 amino acids to about 18 amino acids, about 5 amino acids to about 16 amino acids, about 5 amino acids to about 15 amino acids, about 5 amino acids to about 14 amino acids, about 5 amino acids to about 12 amino acids, about 5 amino acids to about 10 amino acids, about 5 amino acids to about 8 amino acids, about 5 amino acids to about 6 amino acids, about 6 amino acids to about 25 amino acids, about 6 amino acids to about 24 amino acids, about 6 amino acids to about 22 amino acids, about 6 amino acids to about 20 amino acids, about 6 amino acids to about 18 amino acids, about 6 amino acids to about 16 amino acids, about 6 amino acids to about 15 amino acids, about 6 amino acids to about 14 amino acids, about 6 amino acids to about 12 amino acids, about 6 amino acids to about 10 amino acids, about 6 amino acids to about 8 amino acids, about 8 amino acids to about 25 amino acids, about 8 amino acids to about 24 amino acids, about 8 amino acids to about 22 amino acids, about 8 amino acids to about 20 amino acids, about 8 amino acids to about 18 amino acids, about 8 amino acids to about 16 amino acids, about 8 amino acids to about 15 amino acids, about 8 amino acids to about 14 amino acids, about 8 amino acids to about 12 amino acids, about 8 amino acids to about 10 amino acids, about 10 amino acids to about 25 amino acids, about 10 amino acids to about 24 amino acids, about 10 amino acids to about 22 amino acids, about 10 amino acids to about 20 amino acids, about 10 amino acids to about 18 amino acids, about 10 amino acids to about 16 amino acids, about 10 amino acids to about 15 amino acids, about 10 amino acids to about 14 amino acids, about 10 amino acids to about 12 amino acids, about 12 amino acids to about 25 amino acids, about 12 amino acids to about 24 amino acids, about 12 amino acids to about 22 amino acids, about 12 66 CYTX-115-PCT 4862-0152WO1 amino acids to about 20 amino acids, about 12 amino acids to about 18 amino acids, about 12 amino acids to about 16 amino acids, about 12 amino acids to about 15 amino acids, about 12 amino acids to about 14 amino acids, about 14 amino acids to about 25 amino acids, about 14 amino acids to about 24 amino acids, about 14 amino acids to about 22 amino acids, about 14 amino acids to about 20 amino acids, about 14 amino acids to about 18 amino acids, about 14 amino acids to about 16 amino acids, about 14 amino acids to about 15 amino acids, about 15 amino acids to about 25 amino acids, about 15 amino acids to about 24 amino acids, about 15 amino acids to about 22 amino acids, about 15 amino acids to about 20 amino acids, about 15 amino acids to about 18 amino acids, about 15 amino acids to about 16 amino acids, about 16 amino acids to about 25 amino acids, about 16 amino acids to about 24 amino acids, about 16 amino acids to about 22 amino acids, about 16 amino acids to about 20 amino acids, about 16 amino acids to about 18 amino acids, about 18 amino acids to about 25 amino acids, about 18 amino acids to about 24 amino acids, about 18 amino acids to about 22 amino acids, about 18 amino acids to about 20 amino acids, about 20 amino acids to about 25 amino acids, about 20 amino acids to about 24 amino acids, about 20 amino acids to about 22 amino acids, about 22 amino acid to about 25 amino acids, about 22 amino acid to about 24 amino acids, or about 24 amino acid to about 25 amino acids). [00190] In some aspects of any of the activable IL12 fusion proteins or AICs described herein, the linker includes a total of about 1 amino acid, about 2 amino acids, about 3 amino acids, about 4 amino acids, about 5 amino acids, about 6 amino acids, about 7 amino acids, about 8 amino acids, about 9 amino acids, about 10 amino acids, about 11 amino acids, about 12 amino acids, about 13 amino acids, about 14 amino acids, about 15 amino acids, about 16 amino acids, about 17 amino acids, about 18 amino acids, about 19 amino acids, about 20 amino acids, about 21 amino acids, about 22 amino acids, about 23 amino acids, about 24 amino acids, or about 25 amino acids. [00191] In some aspects, a linker is rich in glycine (Gly or G) residues. In some aspects, the linker is rich in serine (Ser or S) residues. In some aspects, the linker is rich in glycine and serine residues. In some aspects, the linker has one or more glycine-serine residue pairs (GS) (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more GS pairs). In some aspects, the linker has one or more Gly-Gly-Gly-Ser (GGGS; SEQ ID NO: 61) sequences (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more GGGS sequences). In some aspects, the linker has one or more Gly-Gly-Gly-Gly-Ser (GGGGS; SEQ ID NO: 62) sequences (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more GGGGS sequences). In some aspects, the 67 CYTX-115-PCT 4862-0152WO1 linker has one or more Gly-Gly-Ser-Gly (GGSG; SEQ ID NO: 63) sequences (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more GGSG sequences). [00192] In some aspects, a linker includes any one of or a combination of one or more of: G, GG, GSSGGSGGSGG (SEQ ID NO: 64), GGGS (SEQ ID NO: 61), GGGSGGGS (SEQ ID NO: 65), GGGSGGGSGGGS (SEQ ID NO: 66), GGGGSGGGGSGGGGS (SEQ ID NO: 67), GGGGSGGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 68), GGGGSGGGGS (SEQ ID NO: 69), GGGGS (SEQ ID NO: 62), GS, GGGGSGS (SEQ ID NO: 70), GGGGSGGGGSGGGGSGS (SEQ ID NO: 71), GGSLDPKGGGGS (SEQ ID NO: 72), PKSCDKTHTCPPCPAPELLG (SEQ ID NO: 73), SKYGPPCPPCPAPEFLG (SEQ ID NO: 74), GKSSGSGSESKS (SEQ ID NO: 75), GSTSGSGKSSEGKG (SEQ ID NO: 76), GSTSGSGKSSEGSGSTKG (SEQ ID NO: 77), and GSTSGSGKPGSGEGSTKG (SEQ ID NO: 78). [00193] Non-limiting examples of linkers can include a sequence that is at least 70% identical (e.g., at least 72%, at least 74%, at least 75%, at least 76%, at least 78%, at least 80%, at least 82%, at least 84%, at least 85%, at least 86%, at least 88%, at least 90%, at least 92%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical) to GGGS (SEQ ID NO: 61), GSSGGSGGSGG (SEQ ID NO: 64), GGGGSGGGGSGGGGS (SEQ ID NO: 67), GGGGSGS (SEQ ID NO: 70), GGGGSGGGGSGGGGSGS (SEQ ID NO: 71), GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 79), GGSLDPKGGGGS (SEQ ID NO: 72), and GSTSGSGKPGSSEGST (SEQ ID NO: 80). [00194] In some aspects, the linker includes a sequence selected from the group of: GGSLDPKGGGGS (SEQ ID NO: 72), GGGGSGGGGSGGGGSGS (SEQ ID NO: 71), GGGGSGS (SEQ ID NO: 70), GS, (GS)n, (GGS)n, (GSGGS)n (SEQ ID NO: 81) and (GGGS)n (SEQ ID NO: 61), GGSG (SEQ ID NO: 63), GGSGG (SEQ ID NO: 82), GSGSG (SEQ ID NO: 83), GSGGG (SEQ ID NO: 84), GGGSG (SEQ ID NO: 85), GSSSG (SEQ ID NO: 86), GGGGSGGGGSGGGGS (SEQ ID NO: 67), GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 79), GSTSGSGKPGSSEGST (SEQ ID NO: 226), (GGGGS)n (SEQ ID NO: 216), wherein n is an integer of at least one. In some aspects, the linker includes a sequence selected from the group consisting of: GGSLDPKGGGGS (SEQ ID NO: 219), GGGGSGGGGSGGGGSGS (SEQ ID NO: 218), GGGGSGS (SEQ ID NO: 217), and GS. In some aspects, the linker includes a sequence selected from the group of: GGGGSGGGGSGGGGS (SEQ ID NO: 213), GGGGSGGGGSGGGGSGGGGS (SEQ ID NO: 235), and GSTSGSGKPGSSEGST (SEQ ID 68 CYTX-115-PCT 4862-0152WO1 NO: 80). In some aspects of any of the activatable IL12 fusion proteins or AICs described herein, the linker includes a sequence selected from the group of: GGGGSGGGGSGGGGS (SEQ ID NO: 67) or GGGGS (SEQ ID NO: 62). In some aspects, the linker comprises a sequence of GGGS (SEQ ID NO: 61). In some aspects, the linker comprises a single glycine residue (G), or a sequence of two glycine residues (GG). In some aspects, the linker includes a sequence selected from SEQ ID NOs 61-98. [00195] In some aspects, an activable IL12 fusion protein or AIC can include one, two, three, four, five, six, seven, eight, nine, or ten linker sequence(s) (e.g., the same or different linker sequences of any of the exemplary linker sequences described herein or known in the art). In some aspects, a linker comprises sulfo-SIAB, SMPB, and sulfo-SMPB, wherein the linkers react with primary amines sulfhydryls. [00196] In some aspects, a MM-DD linking region (flexible linker or flexible linker and CM) is the stretch of amino acid residues between the C-terminus of the MM and the amino acid residue that is N-terminally adjacent to the proximal point of interaction between the dimerization domains (i.e., the MM-DD linking region does not include the C-terminal amino acid of the MM or the N- terminal amino acid of the DD that forms the proximal point of interaction to the DD of the corresponding second monomer). For example, when the DDs are a pair of Fc domains, the MM- DD linking region is the stretch of amino acid residues between the C-terminus of the MM and the first N-terminal cysteine residue that participates in the disulfide linkage of the Fc (e.g., Cysteine 226 of an IgG1 or IgG4 Fc domain, according to EU numbering). When the DD is not a peptide, then the MM-DD linking region is the stretch of amino acid residues following the C-terminus of the MM until the last amino acid. For example, when the DDs are a biotin-streptavidin pair, the MM-DD linking region of the biotin-containing monomer is the stretch of amino acid residues between the C-terminus of the MM and the biotin molecule, and the MM-DD linking region of the streptavidin-containing monomer is the stretch of amino acid residues between the C-terminus of the MM and the streptavidin molecule. In some aspects, the MM-DD linking region comprises no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids, e.g., 4 to 54, 12 to 21, 17 to 21, or 28 to 54, or 12, 17, 21, 28, or 54 amino acids. [00197] In some aspects, the DD is an Fc and the MM-DD linking region is at least 7 amino acids, counting from the first amino acid after Cys226 (Cysteine 226 of an IgG1 or IgG4 Fc domain, 69 CYTX-115-PCT 4862-0152WO1 according to EU numbering) in the N-terminal direction. In some aspects, the DD is an Fc and the MM-DD linking region is 7 to 300 amino acids, 95 to 300 amino acids, 135 to 300 amino acids, 60 to 241 amino acids, or the MM-DD linking region is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, or at least 150 amino acids. [00198] In some aspects, the DD is an Fc and the IL12-DD linking region (including a flexible linker, or including one or more flexible linkers and one or more CMs, or including one or more flexible linkers, a MM, and one or more CMs) is the stretch of amino acid residues between the C-terminus of the IL12 subunit and the amino acid residue that is N-terminally adjacent to the proximal point of interaction between the dimerization domains (i.e., the IL12-DD linking region does not include the C-terminal amino acid of the IL12 or the N-terminal amino acid of the DD that forms the proximal point of interaction to the DD of the corresponding second monomer). For example, when the DDs are a pair of Fc domains, the IL12-DD linking region is the stretch of amino acid residues between the C-terminus of the IL12 and the first N-terminal cysteine residue that participates in the disulfide linkage of the Fc (e.g., Cysteine 226 of an IgG1 or IgG4 Fc domain, according to EU numbering). In some aspects, the IL12-DD linking region is 40 to 300 amino acids, 95 to 300 amino acids, 135 to 300 amino acids, 60 to 241 amino acids, or the IL12-DD linking region is at least 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, or at least 150 amino acids. In some aspects, the IL12-DD linking region is 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 70 CYTX-115-PCT 4862-0152WO1 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, or 300 amino acids. [00199] In some aspects, a MM-EM linking region (flexible linker or flexible linker and CM) is the stretch of amino acid residues between the C-terminus of the MM and the N-terminus of the EM. For example, when the EM is a human serum albumin (HSA), the MM-EM linking region is the stretch of amino acid residues between the C-terminus of the MM and the first N-terminal residue of the HSA. In some aspects, an activatable IL12 fusion protein or an activatable IL12 construct according to aspects disclosed herein does not include a MM-EM linking region. For example, the C-terminal residue of the MM may be conjugated directly to the N-terminal residue of the EM. In some aspects, the MM-EM linking region is 1 to 300 amino acids, 95 to 300 amino acids, 135 to 300 amino acids, 60 to 241 amino acids, or the linking region is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, or at least 150 amino acids. In some aspects, the MM-EM linking region comprises no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acids, or the linking region may be absent (i.e., comprise a direct bond), e.g., 0 to 60, 4 to 54, 12 to 21, 17 to 21, or 28 to 54, or 12, 17, 21, 28, or 54 amino acids. 71 CYTX-115-PCT 4862-0152WO1 [00200] In some aspects, the linking region (flexible linker or flexible linker and CM) between the EM or DD and the p35 subunit of IL12 comprises no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids. In some aspects, the DD is an Fc and the linking region between the DD and the p35 subunit is the stretch of amino acid residues between the C-terminus of the p35 subunit and the amino acid residue that is N- terminally adjacent to the proximal point of interaction between the dimerization domains (i.e., the linking region between the DD and the p35 subunit does not include the C-terminal amino acid of the p35 subunit or the N-terminal amino acid of the DD that forms the proximal point of interaction to the DD of the corresponding second monomer). For example, when the DDs are a pair of Fc domains, the linking region between the DD and the p35 subunit is the stretch of amino acid residues between the C-terminus of the p35 subunit and the first N-terminal cysteine residue that participates in the disulfide linkage of the Fc (e.g., Cysteine 226 of an IgG1 or IgG4 Fc domain, according to EU numbering). [00201] In some aspects, the linking region (flexible linker or flexible linker and CM) between the EM or DD and the p40 subunit of IL12 comprises no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids. In some aspects, the DD is an Fc and the linking region between the DD and the p40 subunit is the stretch of amino acid residues between the C-terminus of the p40 subunit and the amino acid residue that is N- terminally adjacent to the proximal point of interaction between the dimerization domains (i.e., the linking region between the DD and the p40 subunit does not include the C-terminal amino acid of the p40 subunit or the N-terminal amino acid of the DD that forms the proximal point of interaction to the DD of the corresponding second monomer). For example, when the DDs are a pair of Fc domains, the linking region between the DD and the p40 subunit is the stretch of amino acid residues between the C-terminus of the p40 subunit and the first N-terminal cysteine residue that participates in the disulfide linkage of the Fc (e.g., Cysteine 226 of an IgG1 or IgG4 Fc domain, according to EU numbering). [00202] In some aspects, the linking region (flexible linker or flexible linker and CM) between the MM and the p35 subunit of IL12 comprises 4 to 60, 12 to 55, 18 to 50, 29 to 43, or no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 72 CYTX-115-PCT 4862-0152WO1 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids. [00203] In some aspects, the linking region (flexible linker or flexible linker and CM) between the MM and the p40 subunit of IL12 comprises 4 to 60, 12 to 55, 18 to 50, 29 to 43, or no more than 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4 amino acids. [00204] In some aspects, a linker between the p40 domain and the p35 domain is 7, 8, 9, 10, 11, 12, 13, 14, or 15 amino acids in length, e.g., 7 amino acids or 15 amino acids. [00205] In some aspects, the linking region (flexible linker or flexible linker and CM) between the MM and the IL12 is 25 to 47 amino acids in length (including any integer in the range of 25 to 47), e.g., 25, 38, or 47 amino acids. In some aspects, the linking region (flexible linker or flexible linker and CM) between the MM and the DD is 25 to 47 amino acids in length (including any integer in the range of 25 to 47), e.g., 25, 38, or 47 amino acids. Masking Moiety (MMs) [00206] In some aspects, the MM comprises a receptor polypeptide of the receptor for the IL12. In some aspects, the receptor polypeptide of the receptor for the IL12 is an extracellular domain (ECD) of the receptor or a portion thereof. Extracellular domains of cytokine receptors have been identified in the literature, for example, in Wang, Xinquan, et al. “Structural biology of shared cytokine receptors.” Annual review of immunology 27 (2009): 29–60. In some aspects, the MM comprises the full length IL12 receptor ECD. In some aspects, the MM is a truncated version of the IL12 receptor ECD. [00207] In some aspects, the MM is a concatemer of IL12 receptor polypeptide subsequences. For example, the MM may comprise one or more or two or more subsequences of an amino acid sequence corresponding to a polypeptide that binds to IL12 or a receptor polypeptide of the IL12 receptor, according to the method described, e.g., in WO 2024/216146, which is incorporated by reference in its entirety. In certain aspects, the present disclosure includes a CM between two receptor subsequences in a concatemeric MM. [00208] In some aspects, the MM is a polypeptide that binds to IL12 but is not a receptor polypeptide or a subsequence of a receptor polypeptide. In some examples, the MM may be an antibody or antibody fragment (e.g., an antibody variable domain, a Fab fragment, a F(ab’)2 73 CYTX-115-PCT 4862-0152WO1 fragment, an scFv, a single-chain antibody (scab), a variable domain of camelid-type nanobody (VHH), a domain antibody (dAb), a single domain heavy chain antibody, and a single domain light chain antibody), non-immunoglobulin proteins that mimic antibody binding and/or structure (e.g., anticalins, affilins, affibody molecules, affimers, affitins, alphabodies, avimers, adnectins, DARPins, fynomers, kunitz domain peptides, monobodies), and binding domains based on other engineered scaffolds such as SpA, GroEL,fibronectin, lipocallin and CTLA-4 scaffolds that bind to IL12 such that it interrupts IL12 binding to its target. In some examples, the MM may be a peptide that binds to IL12 and interrupts IL12 binding to its target. [00209] In some aspects, the MM is an amino acid sequence of about 200 to about 300 amino acids including any number of amino acids or range of amino acids within about 200 to about 300. In some aspects, the MM is 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, or 300 amino acids in length. [00210] Methods for screening candidate peptides to obtain MM peptides that selectively and/or specifically bind IL12 can include protein display methods and methods of screening candidate peptides described in, for example, US20200308243A1, WO2009025846A2 and WO2010081173, which are incorporated herein by reference in their entireties. [00211] In some aspects, the MM includes a sequence disclosed in US Pat. 11,667,687, US Pat. 11,718,655, and US Pat. 11,634,467, which are incorporated herein by reference in their entireties for all purposes. Exemplary and non-limiting MMs are provided in Table 1 below. [00212] In some aspects, the MM comprises an antibody or fragment thereof that binds to and reduces or inhibits one or more activities of IL12, such as, for example, an scFv, a single domain antibody, and the like. In certain aspects, the MM comprises an scFv. In some aspects, the scFv binds to and reduces or inhibits one or more activities of the p40 subunit. In other aspects, the scFv binds to and reduces or inhibits one or more activities of the p35 subunit. In certain aspects, the activatable IL12 fusion protein or AIC comprises an MM having a HCDR1 sequence comprising SYGMH (SEQ ID NO: 1355), a HCDR2 sequence comprising FIRYDGSNKYYADSVKG (SEQ ID NO: 1356), a HCDR3 sequence comprising HGSHDN 74 CYTX-115-PCT 4862-0152WO1 (SEQ ID NO: 1357), a LCDR1 sequence comprising SGSRSNIGSNTVK (SEQ ID NO: 1358), a LCDR2 sequence comprising YNDQRPS (SEQ ID NO: 1359), and LCDR3 sequence comprising QSYDRYTHPALL (SEQ ID NO: 1360). In certain aspects, the activatable IL12 fusion protein or AIC comprises an MM comprising SEQ ID NO: 1361, SEQ ID NO: 1362, or both. [00213] In some aspects, the amino acid sequence of the MM comprises a CM. For example, the MM includes an internal linker comprising a CM within the MM sequence. In some aspects, the MM comprising a CM within the MM has a structure comprising: MM’-CM-MM”, wherein “-” comprises a linker or a direct bond. In some aspects, the linker (“-”) is about 2 amino acids to about 6 amino acids. In some aspects, the MM is a concatenated sequence of two or more subsequences joined by a linker comprising a CM, and MM’ comprises a first peptide and MM” comprises a second peptide so that the MM’ and the MM” are linked together by the CM and optionally one or more linkers to develop a single concatenated peptide as a masking moiety (MM). In some aspects, MM’ and MM” do not independently function as masking moieties. In some aspects, the two or more concatenated peptides linked by a linker comprising a CM may be different from each other or identical. For example, MM’ and MM” may be the same sequence or a different sequence. In some aspects, the MM is a concatenated sequence of two or more IL12 receptor polypeptide subsequences that are identical, such that MM’ and MM” comprise the same subsequence, for example, the same IL12 receptor polypeptide subsequence. [00214] In some aspects, the MM is a concatenated sequence of two or more polypeptide subsequences that are different. In some aspects, the MM’ may be a subsequence corresponding to an N-terminal portion of the MM sequence and the MM” may be a subsequence corresponding to a C-terminal portion of the MM sequence so that MM’ and MM” are linked together by a CM and optionally one or more linkers to develop a single concatenated peptide as a masking moiety (MM). For example, the MM may comprise a variable light (VL) and variable heavy (VH) chain linked by a linker comprising a CM between the VL and VH chains. In some aspects, the MM’ comprises a variable light (VL) chain and the MM” comprises a variable heavy (VH) chain, or the MM’ comprises the VH and the MM” comprises the VL In some aspects, the MM is an scFv and comprises a CM between the VL and the VH with a structure comprising: VL-CM-VH or VH- CM-VL, wherein “-” comprises a linker or a direct bond. In some aspects, the MM comprises a concatemer of IL 12 receptor polypeptide subsequences capable of binding to IL12 (e.g., a peptide or an extracellular domain (ECD)). In some aspects, MM’ comprises a subsequence corresponding 75 CYTX-115-PCT 4862-0152WO1 to an N-terminal portion of an IL12 receptor amino acid sequence and MM” comprises a subsequence corresponding to a C-terminal portion of the IL12 receptor amino acid sequence so that the N-terminal portion (MM’) and the C-terminal portion (MM”) are linked together by the CM and optionally one or more linkers to develop a single concatenated peptide as a masking moiety (MM). For example, the MM may comprise a structure IL12R’-CM-IL12R”, wherein IL12R’ corresponds to a first stretch of amino acids corresponding to a IL12 receptor polypeptide and IL12R” corresponds to a second stretch of amino acids corresponding to a IL12 receptor polypeptide, and wherein the stretch of amino acids for IL12R’ and IL12R” may be partially overlapping or non-overlapping. In some aspects, the MM is an amino acid sequence of less than 50 amino acids including any number of amino acids or range of amino acids within 1 to 50. In some aspects, the MM is no more than 40 amino acids in length. In some aspects, the MM is no more than 30 amino acids in length. In preferred embodiments, the MM is no more than 20 amino acids in length. In some aspects, the MM is no more than 19, 18, 17, 16, or 15 amino acids in length. In some aspects, the MM is at least 1, 2, 3, 4 amino acids. In some aspects, the MM is 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 amino acids. In some aspects, the MM is 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 29, or 40 amino acids in length. In some aspects, the MM is operably linked to the p40 subunit of IL12, while in other embodiments the MM is operably linked to the p35 subunit of IL12. In some aspects, the MM is linked directly to an IL12 subunit, while in other aspects the MM is linked to an IL12 subunit via a linker, and placed into a functional relationship such that the MM is in a position to bind to the cytokine and inhibit the interaction between IL12 and its binding partner in the body of a subject. Exemplary MMs are listed in Table 1. Table 1. SEQ ID NO Description MM Sequence Q E S L I 76 CYTX-115-PCT 4862-0152WO1 PADTHTEPVALNISVGTNGTTMYWPARAQSMTYCIEWQ PVGQDGGLATCSLTAPQDPDPAGMATYSWSRESGAMGQ H F L S L T D P S Q E I R C A S L R N T D E L L L G P L 77 CYTX-115-PCT 4862-0152WO1 ISENIKPYICYEIRVHALSESQGGCSSIRGDSKHKAPVSGP HITAITEKKERLFISWTHIPFPEQRGCILHYRIYWKERDST R G P K T Y Q G T Y Q G L N N S P F D S L S F G 78 CYTX-115-PCT 4862-0152WO1 1511 Briakinuma QSVLTQPPSVSGAPGQRVTISCSGSRSNIGSNTVKWYQQL b PGTAPKLLIYYNDQRPSGVPDRFSGSKSGTSASLAITGLQ s M S L T D P S S L S L T D N T D E L L F D L L F 79 CYTX-115-PCT 4862-0152WO1 TISRDNSKNTLYLQMNSLRAEDTAVYYCKTHGSHDNWG QGTMVTVSS 80 CYTX-115-PCT 4862-0152WO1 1358 MM LCDR1 GSRSNIGSNTVK 1359 MM LCDR2 YNDQRPS N S L Q E S Q E S Q E S Q Q Q Q E Q 81 CYTX-115-PCT 4862-0152WO1 AGVSVLYTVTLWVESWARNQTEKSPEVTLQLYNSVKYE P S L T D P S S L T D S L N T D E L 82 CYTX-115-PCT 4862-0152WO1 1443 IL12 MM AIRGSVGFTHYADSVKG Nanobody F Q 83 CYTX-115-PCT 4862-0152WO1 KVTVYLQMNNLKPEDTGVYYCAASEGPATIRQNTYPDW GQGTQVTVSS Q R Q L V S T T R N T V N R E T 84 CYTX-115-PCT 4862-0152WO1 VYLQMNSLKHEDTALYYCATDLGRKLGTQSREYGYWG QGTQVTVSS N R T N S Q V T Q N Y R W Y T Q N A T 85 CYTX-115-PCT 4862-0152WO1 1479 IL12 MM QVQLVESGGGSVQAGGSLRLSCAASGRTFNTKAIGWFRQ VHH APGKEREFVAAISWGGGTIRYADSVKGRVTISRDDAKNT T Q V Q Y T G Q V Q V T S T G R T G Q Y 86 CYTX-115-PCT 4862-0152WO1 1490 IL12 MM QVQLVESGGGLVQPGGSLRLSCAASGSIAEIYVMGWYRQ VHH APGKQREIVATTPSSGRTNIADSVKGRFIISRDFVKNTVAL Q T T R T T G Q T G R N Q W R W 87 CYTX-115-PCT 4862-0152WO1 1501 IL12 MM EVQLVESGGGSVQTGGSLRLSCKVSEGSFMRYNMGWFR VHH QAPGKERDFVAAMSGALALIRYADSVKGRFTISRDNSKN V Q V Q V Optional Components [00215] In some aspects, a spacer (or “header”) is employed in a polypeptide or construct of the present disclosure. As used herein, the term “spacer” refers to an amino acid residue or amino acid sequence incorporated at a free terminus of the mature activable IL12 fusion protein or AIC. In some aspects, a spacer comprises one or more glutamine (Q) residues. In some aspects, residues in the spacer minimize aminopeptidase and/or exopeptidase action to prevent cleavage of N- terminal amino acids. Illustrative and non-limiting spacer amino acid sequences may comprise or consist of any of the following exemplary amino acid sequences: QGQSGS (SEQ ID NO: 87); GQSGS (SEQ ID NO: 88); QSGS (SEQ ID NO: 89); SGS; GS; S; QGQSGQG (SEQ ID NO: 90); GQSGQG (SEQ ID NO: 91); QSGQG (SEQ ID NO: 92); SGQG (SEQ ID NO: 93); GQG; QG; G; QGQSGQ (SEQ ID NO: 94); GQSGQ (SEQ ID NO: 95); QSGQ (SEQ ID NO: 96); QGQSG (SEQ ID NO: 97); QGQS (SEQ ID NO: 98); SGQ; GQ; and Q. In some aspects, spacer sequences are omitted. Conjugation to Agents [00216] This disclosure also provides methods and materials for including additional elements in any of the activatable IL12 fusion proteins or AICs described herein including, for example, a targeting moiety to facilitate delivery to a cell or tissue of interest, an agent (e.g., a therapeutic agent, an antineoplastic agent), a toxin, or a fragment thereof. 88 CYTX-115-PCT 4862-0152WO1 [00217] In some aspects, the activatable IL12 fusion protein or AIC is conjugated to a cytotoxic agent, including, without limitation, a toxin (e.g., an enzymatically active toxin of bacterial, fungal, plant, or animal origin, or fragments thereof) or a radioactive isotope. In some aspects, the activatable IL12 fusion protein or AIC is conjugated to a cytotoxic agent including, without limitation, a toxin (e.g., an enzymatically active toxin of bacterial, fungal, plant, or animal origin, or fragments thereof), or a radioactive isotope. [00218] Non-limiting exemplary cytotoxic agents that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: dolastatins and derivatives thereof (e.g., auristatin E, AFP, monomethyl auristatin D (MMAD), monomethyl auristatin F (MMAF), monomethyl auristatin E (MMAE), desmethyl auristatin E (DMAE), auristatin F, desmethyl auristatin F (DMAF), dolastatin 16 (DmJ), dolastatin 16 (Dpv), auristatin derivatives (e.g., auristatin tyramine, auristatin quinolone), maytansinoids (e.g., DM-1, DM-4), maytansinoid derivatives, duocarmycin, alpha-amanitin, turbostatin, phenstatin, hydroxyphenstatin, spongistatin 5, spongistatin 7, halistatin 1, halistatin 2, halistatin 3, halocomstatin, pyrrolobenzimidazoles (PBI), cibrostatin6, doxaliform, cemadotin analogue (CemCH2-SH), Pseudomonas toxin A (PES8) variant, Pseudomonase toxin A (ZZ-PE38) variant, ZJ-101, anthracycline, doxorubicin, daunorubicin, bryostatin, camptothecin, 7-substituted campothecin, 10, 11- difluoromethylenedioxycamptothecin, combretastatins, debromoaplysiatoxin, KahaMide-F, discodermolide, and Ecteinascidins. [00219] Non-limiting exemplary enzymatically active toxins that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: diphtheria toxin, exotoxin A chain from Pseudomonas aeruginosa, ricin A chain, abrin A chain, modeccin A chain, alpha- sarcin, Aleuriies fordii proteins, dianfhin proteins, Phytoiaca Americana proteins (e.g., PAPI, PAPII, and PAP-8), momordica charantia inhibitor, curcin, crotirs, sapaonaria officinalis inhibitor, geionin, mitogeliin, restrictocin, phenomycin, neomycin, and tricothecenes. [00220] Non-limiting exemplary anti-neoplastics that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: adriamycin, cerubidine, bleomycin, alkeran, velban, oncovin, fluorouracil, methotrexate, thiotepa, bisantrene, novantrone, thioguanine, procarabizine, and cytarabine. [00221] Non-limiting exemplary antivirals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: acyclovir, vira A, and symmetrel. 89 CYTX-115-PCT 4862-0152WO1 [00222] Non-limiting exemplary antifungals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: nystatin. [00223] Non-limiting exemplary conjugatable detection reagents that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include:fluorescein and derivatives thereof,fluorescein isothiocyanate (FITC). [00224] Non-limiting exemplary antibacterials that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: aminoglycosides, streptomycin, neomycin, kanamycin, amikacin, gentamicin, and tobramycin. [00225] Non-limiting exemplary 3beta,16beta,17alpha-trihydroxycholest-5-en-22-one 16-O-(2- O-4-methoxybenzoyl-beta-D-xylopyranosyl)-(1->3)-(2-O-acetyl-alpha-L-arabinopyranoside) (OSW-1) that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: s-nitrobenzyloxycarbonyl derivatives of O6-benzylguanine, topoisomerase inhibitors, hemiasterlin, cephalotaxine, homoharringionine, pyrrol obenzodiazepine dimers (PBDs), functionalized pyrrolobenzodiazepenes, calcicheamicins, podophyiitoxins, taxanes, and vinca alkoids. [00226] Non-limiting exemplary radiopharmaceuticals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: 123I , 89Zr, 125I, 131I, 99mTc, 201T1, 62Cu, 18F, 68Ga, 13 N, 15O, 38K, 82Rb, 111In, 133Xe, 11C, and 99mTc (Technetium). [00227] Non-limiting exemplary heavy metals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: barium, gold, and platinum. [00228] Non-limiting exemplary anti-mycoplasmals that can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein include: tylosin, spectinomycin, streptomycin B, ampicillin, sulfanilamide, polymyxin, and chloramphenicol. [00229] Those of ordinary skill in the art will recognize that a large variety of possible moieties can be conjugated to any of the activatable IL12 fusion proteins or AICs described herein. Conjugation can include any chemical reaction that will bind the two molecules so long as the activatable IL12 fusion protein or AIC and the other moiety retain their respective activities. Conjugation can include many chemical mechanisms, e.g., covalent binding, affinity binding, intercalation, coordinate binding, and complexation. In some aspects, the preferred binding is covalent binding. Covalent binding can be achieved either by direct condensation of existing side chains or by the incorporation of external bridging molecules. Many bivalent or polyvalent linking 90 CYTX-115-PCT 4862-0152WO1 agents are useful in conjugating any of the activatable IL12 fusion proteins or AICs described herein. For example, conjugation can include organic compounds, such as thioesters, carbodiimides, succinimide esters, glutaraldehyde, diazobenzenes, and hexamethylene diamines. In some aspects, the activatable IL12 fusion proteins or AICs can include, or otherwise introduce, one or more non-natural amino acid residues to provide suitable sites for conjugation. [00230] In some aspects, an agent and/or conjugate is attached by disulfide bonds (e.g., disulfide bonds on a cysteine molecule) to the antigen-binding domain. Since many cancers naturally release high levels of glutathione, a reducing agent, glutathione present in the cancerous tissue microenvironment can reduce the disulfide bonds, and subsequently release the agent and/or the conjugate at the site of delivery. [00231] In some aspects, when the conjugate binds to its target in the presence of complement within the target site (e.g., diseased tissue, such as cancerous tissue), the amide or ester bond attaching the conjugate and/or agent to the linker is cleaved, resulting in the release of the conjugate and/or agent in its active form. These conjugates and/or agents when administered to a subject, will accomplish delivery and release of the conjugate and/or the agent at the target site (e.g., diseased tissue, such as cancerous tissue). These conjugates and/or agents are particularly effective for the in vivo delivery of any of the conjugates and/or agents described herein. [00232] In some aspects, the linker is not cleavable by enzymes of the complement system. For example, the conjugate and/or agent is released without complement activation since complement activation ultimately lyses the target cell. In such embodiments, the conjugate and/or agent is to be delivered to the target cell (e.g., hormones, enzymes, corticosteroids, neurotransmitters, or genes). Furthermore, the linker is mildly susceptible to cleavage by serum proteases, and the conjugate and/or agent is released slowly at the target site. [00233] In some aspects, the conjugate and/or agent is designed such that the conjugate and/or agent is delivered to the target site (e.g., disease tissue, such as cancerous tissue) but the conjugate and/or agent is not released. [00234] In some aspects, the conjugate and/or agent is attached to the activatable IL12 fusion protein or AIC either directly or via a non-cleavable linker. Exemplary non-cleavable linkers include amino acids (e.g., D-amino acids), peptides, or other organic compounds that may be modified to include functional groups that can subsequently be utilized in attachment to the activatable IL12 fusion protein or AIC by methods described herein. 91 CYTX-115-PCT 4862-0152WO1 [00235] In some aspects, the activatable IL12 fusion proteins or AICs include at least one point of conjugation for an agent. In some aspects, all possible points of conjugation are available for conjugation to an agent. In some aspects, the one or more points of conjugation include, without limitation, sulfur atoms involved in disulfide bonds, sulfur atoms involved in interchain disulfide bonds, sulfur atoms involved in interchain sulfide bonds but not sulfur atoms involved in intrachain disulfide bonds, and/or sulfur atoms of cysteine or other amino acid residues containing a sulfur atom. In such cases, residues may occur naturally in the protein construct structure or are incorporated into the protein construct using methods including, without limitation, site-directed mutagenesis, chemical conversion, or mis-incorporation of non-natural amino acids. [00236] This disclosure also provides methods and materials for preparing an activatable IL12 fusion protein or AIC for conjugation. In some aspects of any of the activatable IL12 fusion proteins or AICs described herein, an activatable IL12 fusion protein or AIC is modified to include one or more interchain disulfide bonds. For example, disulfide bonds in the activatable IL12 fusion proteins or AICs can undergo reduction following exposure to a reducing agent such as, without limitation, TCEP, DTT, or β-mercaptoethanol. In some cases, the reduction of the disulfide bonds is only partial. As used herein, the term partial reduction refers to situations where an activatable IL12 fusion protein or AIC is contacted with a reducing agent and a fraction of all possible sites of conjugation undergo reduction (e.g., not all disulfide bonds are reduced). In some aspects, an activatable IL12 fusion protein or AIC is partially reduced following contact with a reducing agent if less than 99%, (e.g., less than 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10% or less than 5%) of all possible sites of conjugation are reduced. In some aspects, the activatable IL12 fusion protein or AIC having a reduction in one or more interchain disulfide bonds is conjugated to a drug reactive with free thiols. [00237] This disclosure also provides methods and materials for conjugating a therapeutic agent to a particular location on an activatable IL12 fusion protein or AIC. In some aspects, an activatable IL12 fusion protein or AIC is modified so that the therapeutic agents can be conjugated to the activatable IL12 fusion protein or AIC at particular locations on the activatable IL12 fusion protein or AIC. For example, an activatable IL12 fusion protein or AIC can be partially reduced in a manner that facilitates conjugation to the activatable IL12 fusion protein or AIC. In such cases, partial reduction of the activatable IL12 fusion protein or AIC occurs in a manner that conjugation sites in the activatable IL12 fusion protein or AIC are not reduced. In some aspects, the conjugation 92 CYTX-115-PCT 4862-0152WO1 site(s) on the activatable IL12 fusion protein or AIC are selected to facilitate conjugation of an agent at a particular location on the protein construct. Various factors can influence the “level of reduction” of the activatable IL12 fusion protein or AIC upon treatment with a reducing agent. For example, without limitation, the ratio of reducing agent to an activatable IL12 fusion protein or AIC, length of incubation, incubation temperature, and/or pH of the reducing reaction solution can require optimization in order to achieve partial reduction of the activatable IL12 fusion protein or AIC with the methods and materials described herein. Any appropriate combination of factors (e.g., ratio of reducing agent to an activatable IL12 fusion protein or AIC, the length and temperature of incubation with reducing agent, and/or pH of reducing agent) can be used to achieve partial reduction of the activatable IL12 fusion protein or AIC (e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites). [00238] An effective ratio of reducing agent to an activatable IL12 fusion protein or AIC can be any ratio that at least partially reduces the activatable IL12 fusion protein or AIC in a manner that allows conjugation to an agent (e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites). In some aspects, the ratio of reducing agent to an activatable IL12 fusion protein or AIC will be in a range from about 20:1 to 1:1, from about 10:1 to 1:1, from about 9:1 to 1:1, from about 8:1 to 1:1, from about 7:1 to 1:1, from about 6:1 to 1:1, from about 5:1 to 1:1, from about 4:1 to 1:1, from about 3:1 to 1:1, from about 2:1 to 1:1, from about 20:1 to 1:1.5, from about 10:1 to 1:1.5, from about 9:1 to 1:1.5, from about 8:1 to 1:1.5, from about 7:1 to 1:1.5, from about 6:1 to 1:1.5, from about 5:1 to 1:1.5, from about 4:1 to 1:1.5, from about 3:1 to 1:1.5, from about 2:1 to 1:1.5, from about 1.5:1 to 1:1.5, or from about 1:1 to 1:1.5. In some aspects, the ratio is in a range of from about 5:1 to 1:1. In some aspects, the ratio is in a range of from about 5:1 to 1.5:1. In some aspects, the ratio is in a range of from about 4:1 to 1:1. In some aspects, the ratio is in a range from about 4:1 to 1.5:1. In some aspects, the ratio is in a range from about 8:1 to about 1:1. In some aspects, the ratio is in a range of from about 2.5:1 to 1:1. [00239] An effective incubation time and temperature for treating an activatable IL12 fusion protein or AIC with a reducing agent can be any time and temperature that at least partially reduces the activatable IL12 fusion protein or AIC in a manner that allows conjugation of an agent to an activatable IL12 fusion protein or AIC (e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites). In some aspects, the incubation time and temperature for 93 CYTX-115-PCT 4862-0152WO1 treating an activatable IL12 fusion protein or AIC will be in a range from about 1 hour at 37 °C to about 12 hours at 37 °C (or any subranges therein). [00240] An effective pH for a reduction reaction for treating an activatable IL12 fusion protein or AIC with a reducing agent can be any pH that at least partially reduces the activatable IL12 fusion protein or AIC in a manner that allows conjugation of the activatable IL12 fusion protein or AIC to an agent (e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites). [00241] When a partially-reduced an activatable IL12 fusion protein or AIC is contacted with an agent containing thiols, the agent can conjugate to the interchain thiols in the activatable IL12 fusion protein or AIC. An agent can be modified in a manner to include thiols using a thiol- containing reagent (e.g., cysteine or N-acetyl cysteine). For example, the activatable IL12 fusion protein or AIC can be partially reduced following incubation with reducing agent (e.g., TCEP) for about 1 hour at about 37 °C at a desired ratio of reducing agent to activatable IL12 fusion protein or AIC. An effective ratio of reducing agent to activatable IL12 fusion protein or AIC can be any ratio that partially reduces at least two interchain disulfide bonds located in the activatable IL12 fusion protein or AIC in a manner that allows conjugation of a thiol-containing agent (e.g., general reduction of possible conjugation sites or reduction at specific conjugation sites). [00242] In some aspects, an activatable IL12 fusion protein or AIC is reduced by a reducing agent in a manner that avoids reducing any intrachain disulfide bonds. In some aspects, an activatable IL12 fusion protein or AIC is reduced by a reducing agent in a manner that avoids reducing any intrachain disulfide bonds and reduces at least one interchain disulfide bond. [00243] In some aspects of any of the activatable IL12 fusion proteins or AICs described herein, the activatable IL12 fusion protein or AIC can also include an agent conjugated to the activatable IL12 fusion protein or AIC. In some aspects, the conjugated agent is a therapeutic agent. [00244] In some aspects, the agent (e.g., agent conjugated to an activatable IL12 fusion protein or AIC) is a detectable moiety such as, for example, a label or other marker. For example, the agent is or includes a radiolabeled amino acid, one or more biotinyl moieties that can be detected by marked avidin (e.g., streptavidin containing afluorescent marker or enzymatic activity that can be detected by optical or calorimetric methods), one or more radioisotopes or radionuclides, one or morefluorescent labels, one or more enzymatic labels, and/or one or more chemiluminescent agents. In some aspects, detectable moieties are attached by spacer molecules. 94 CYTX-115-PCT 4862-0152WO1 [00245] In some aspects, the agent (e.g., cytotoxic agent conjugated to an activatable IL12 fusion protein or AIC) is linked to the activatable IL12 fusion protein or AIC using a carbohydrate moiety, sulfhydryl group, amino group, or carboxylate group. [00246] In some aspects of any of the activatable IL12 fusion proteins or AICs described herein conjugated to an agent, the agent (e.g., cytotoxic agent conjugated to an activatable IL12 fusion protein or AIC) is conjugated to the activatable IL12 fusion protein or AIC via a cleavable conjugation linker and/or a CM (also referred to as a cleavable sequence). In some aspects, the agent (e.g., cytotoxic agent conjugated to an activatable IL12 fusion protein or AIC) is conjugated to a cysteine or a lysine in the activatable IL12 fusion protein or AIC. In some aspects, the agent (e.g., cytotoxic agent conjugated to an activatable IL12 fusion protein or AIC) is conjugated to another residue of the activatable IL12 fusion protein or AIC, such as those residues disclosed herein. In some aspects, the linker is a thiol-containing linker. In some aspects, the linker is a non- cleavable linker. [00247] Those of ordinary skill in the art will recognize that a large variety of possible moieties can be coupled to the activatable IL12 fusion proteins or AICs of the disclosure. (See, for example, “Conjugate Vaccines”, Contributions to Microbiology and Immunology, J. M. Cruse and R. E. Lewis, Jr (eds), Carger Press, New York, (1989). In general, an effective conjugation of an agent (e.g., cytotoxic agent) to an activatable IL12 fusion protein or AIC can be accomplished by any chemical reaction that will bind the agent to the activatable IL12 fusion protein or AIC while also allowing the agent and the activatable IL12 fusion protein or AIC to retain functionality. [00248] In some aspects of any of the activatable IL12 fusion proteins or AICs conjugated to an agent, a variety of bifunctional protein-coupling agents can be used to conjugate the agent to the activatable IL12 fusion protein or AIC including, without limitation, N-succinimidyl-3-(2- pyridyldithiol) propionate (SPDP), iminothiolane (IT), bifunctional derivatives of imidoesters (e.g., dimethyl adipimidate HCL), active esters (e.g., disuccinimidyl suberate), aldehydes (e.g., glutareldehyde), bis-azido compounds (e.g., bis (p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (e.g., bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (e.g., tolyene 2,6- diisocyanate), and bis-activefluorine compounds (e.g., 1,5-difluoro-2,4-dinitrobenzene). For example, a ricin immunotoxin can be prepared as described in Vitetta et al., Science 238: 1098 (1987). In some aspects, a carbon-14-labeled 1-isothiocyanatobenzyl-3-methyldiethylene 95 CYTX-115-PCT 4862-0152WO1 triaminepentaacetic acid (MX-DTPA) chelating agent can be used to conjugate a radionucleotide to the activatable IL12 fusion protein or AIC. (See, e.g., WO94/11026). [00249] Suitable cleavable conjugation linkers and CMs are described in the literature. (See, for example, Ramakrishnan, et al., Cancer Res. 44:201-208 (1984) describing use of MBS (M- maleimidobenzoyl-N-hydroxysuccinimide ester). See also, U.S. Patent No. 5,030,719, describing use of halogenated acetyl hydrazide derivative coupled to an activatable IL12 fusion protein or AIC by way of an oligopeptide linker. In some aspects, suitable linkers include: (i) EDC (1-ethyl- 3-(3-dimethylamino-propyl) carbodiimide hydrochloride; (ii) SMPT (4-succinimidyloxycarbonyl- alpha-methyl-alpha-(2-pridyl-dithio)-toluene (Pierce Chem. Co., Cat. (21558G); (iii) SPDP (succinimidyl-6 [3-(2-pyridyldithio) propionamido] hexanoate (Pierce Chem. Co., Cat #21651G); (iv) Sulfo-LC-SPDP (sulfosuccinimidyl 6 [3-(2-pyridyldithio)-propianamide] hexanoate (Pierce Chem. Co. Cat. #2165-G); and (v) sulfo-NHS (N-hydroxysulfo-succinimide: Pierce Chem. Co., Cat. #24510) conjugated to EDC. Additional cleavable conjugation linkers include, but are not limited to, SMCC, sulfo-SMCC, SPDB, or sulfo-SPDB. [00250] The cleavable conjugation linkers and CMs described above contain components that have different attributes, thus leading to conjugates with differing physio-chemical properties. For example, sulfo-NHS esters of alkyl carboxylates are more stable than sulfo-NHS esters of aromatic carboxylates. NHS-ester containing linkers are less soluble than sulfo-NHS esters. Further, the linker SMPT contains a sterically-hindered disulfide bond, and can form conjugates with increased stability. Disulfide linkages, are in general, less stable than other linkages because the disulfide linkage is cleaved in vitro, resulting in less conjugate available. Sulfo-NHS, in particular, can enhance the stability of carbodimide couplings. Carbodimide couplings (such as EDC) when used in conjunction with sulfo-NHS, forms esters that are more resistant to hydrolysis than the carbodimide coupling reaction alone. [00251] In some aspects an agent can be conjugated to the activatable IL12 fusion protein or AIC using a modified amino acid sequence included in the amino acid sequence of the activatable IL12 fusion protein or AIC. By inserting conjugation-enabled amino acids at specific locations within the amino acid sequence of the activatable IL12 fusion protein or AIC, the protein construct can be designed for controlled placement and/or dosage of the conjugated agent (e.g., cytotoxic agent). For example, the activatable IL12 fusion protein or AIC can be modified to include a cysteine amino acid residue at positions that provide reactive thiol groups and does not negatively impact 96 CYTX-115-PCT 4862-0152WO1 protein folding and/or assembly and does not alter the target properties. In some aspects, the activatable IL12 fusion protein or AIC can be modified to include one or more non-natural amino acid residues within the amino acid sequence of the activatable IL12 fusion protein or AIC to provide suitable sites for conjugation. In some aspects, the activatable IL12 fusion protein or AIC can be modified to include enzymatically activatable peptide sequences within the amino acid sequence of the activatable IL12 fusion protein or AIC. Nucleic Acids [00252] Provided herein are nucleic acids comprising sequences that encode the activatable IL12 fusion protein or thefirst polypeptide (e.g., any of thefirst polypeptides described herein) and the second polypeptide (e.g., any of the second polypeptides described herein) of any of the activatable IL12 fusion proteins or AICs described herein. In some aspects, a pair of nucleic acids together encode thefirst polypeptide (or the protein portion of thefirst polypeptide) and the second polypeptide (or the protein portion of the second polypeptide). In some aspects, the nucleic acid is a deoxyribonucleic acid (DNA). In other aspects, the nucleic acid is a ribonucleic acid (RNA). The polynucleotide sequence of the nucleic acid may be codon optimized for optimal expression from the desired host cell species. Vectors [00253] Provided herein are vectors and sets of vectors including any of the nucleic acids described herein. One skilled in the art will be capable of selecting suitable vectors or sets of vectors (e.g., expression vectors) for making any of the activatable IL12 fusion proteins or AICs described herein, and using the vectors or sets of vectors to express any of the activatable IL12 fusion proteins or AICs described herein. For example, in selecting a vector or a set of vectors, the cell must be considered because the vector(s) may need to be able to integrate into a chromosome of the cell and/or replicate in it. Exemplary vectors that can be used to produce an activatable IL12 fusion protein or AIC are also described below. [00254] As used herein, “vector” refers to a polynucleotide capable of inducing the expression of a recombinant protein (e.g., afirst or second polypeptide) in a cell (e.g., any of the cells described herein). A “vector” is able to deliver nucleic acids and fragments thereof into a host cell, and includes regulatory sequences (e.g., promoter, enhancer, poly(A) signal). Exogenous 97 CYTX-115-PCT 4862-0152WO1 polynucleotides may be inserted into the expression vector in order to be expressed. The term “vector” also includes artificial chromosomes, plasmids, retroviruses, and baculovirus Vectors. [00255] Methods for constructing suitable vectors that include any of the nucleic acids described herein, and suitable for transforming cells (e.g., mammalian cells) are well-known in the art. See, e.g., Sambrook et al., Eds. “Molecular Cloning: A Laboratory Manual,” 2nd Ed., Cold Spring Harbor Press, 1989 and Ausubel et al., Eds. “Current Protocols in Molecular Biology,” Current Protocols, 1993. [00256] Non-limiting examples of vectors include plasmids, transposons, cosmids, and viral vectors (e.g., any adenoviral vectors (e.g., pSV or pCMV vectors), adeno-associated virus (AAV) vectors, lentivirus vectors, and retroviral vectors), and any Gateway® vectors. A vector can, for example, include sufficient cis-acting elements for expression; other elements for expression can be supplied by the host mammalian cell or in an in vitro expression system. Skilled practitioners will be capable of selecting suitable vectors and mammalian cells for making any of the activatable IL12 fusion proteins or AICs described herein. [00257] In certain aspects activatable IL12 fusion protein or AIC of the present disclosure is made biosynthetically using recombinant technology and expression in a eukaryotic or a prokaryotic species. [00258] In some aspects, the vector includes a nucleic acid encoding thefirst polypeptide and the second polypeptide of any of the AICs described herein. In some aspects, the vector is an expression vector. [00259] In some aspects, a pair of vectors together include a pair of nucleic acids that together encode thefirst polypeptide and the second polypeptide of any of the AICs described herein. In some aspects, the pair of vectors is a pair of expression vectors. Cells [00260] Also provided herein are recombinant host cells that comprise any of the nucleic acids, vector or sets of vectors described herein that encode an activatable IL12 fusion protein or an AIC. As used herein, the term “recombinant host cell” refers to a cell into which an exogenous polynucleotide has been introduced. For example, in some aspects the exogenous polynucleotide is an expression vector. For example, a prokaryotic host cell is a genetically modified prokaryotic host cell (e.g., a bacterium), by virtue of introduction into a suitable prokaryotic host cell of a heterologous nucleic acid, e.g., an exogenous nucleic acid that is foreign to (not found in nature 98 CYTX-115-PCT 4862-0152WO1 in) the prokaryotic host cell, or a recombinant nucleic acid that is not normally found in the prokaryotic host cell; and a subject eukaryotic host cell is a genetically modified eukaryotic host cell, by virtue of introduction into a suitable eukaryotic host cell of a heterologous nucleic acid, e.g., an exogenous nucleic acid that is foreign to the eukaryotic host cell, or a recombinant nucleic acid that is not naturally found in the eukaryotic host cell. [00261] Suitable methods of introducing any of the nucleic acids and/or vectors (e.g., any of the vectors or any of the sets of vectors described herein) described herein into a cell include any method that is known in the art. Non-limiting examples of methods that can be used to introducing a nucleic acid into a cell include: lipofection, calcium phosphate transfection, cationic polymer transfection, viral transduction (e.g., adenoviral transduction, lentiviral transduction), nanoparticle transfection, and electroporation. [00262] In some aspects, the introducing step includes introducing into a cell a vector or vectors (e.g., any of the vectors or sets of vectors described herein) that comprise(s) a nucleic acid encoding the polypeptide(s) that make up any of the activatable IL12 fusion proteins or AICs described herein. [00263] In some aspects of any of the methods described herein, the activatable IL12 fusion proteins or AICs can be produced by any cell, including a prokaryotic cell (e.g., a bacterial cell) or a eukaryotic cell. As used herein, “eukaryotic cell” refers to a cell having a distinct, membrane- bound nucleus. Such cells include, for example, a mammalian cell, an insect cell, a fungal cell, a plant cell, and the like. In some aspects, the eukaryotic cell is a yeast cell, such as Saccharomyces cerevisiae. In some aspects, the eukaryotic cell is a higher eukaryote, such as a mammalian cell, an avian cell, a plant cell, an insect cell, and the like. Non-limiting examples of mammalian cells include a rodent cell (e.g., a mouse cell, a rat cell, a hamster cell, such as a Chinese hamster ovary (CHO) cell, a non-human primate cell, a human cell, such as a human embryonic kidney cell(e.g., HEK293 cells), and the like. In certain aspects, the cell is a prokaryotic cell. Exemplary prokaryotic cells include, for example, an E. coli cell, a Bacillus sp. cell, and the like. [00264] When the activatable IL12 fusion protein or AIC comprises at least a first polypeptide and a second polypeptide, the cell contains the pair of nucleic acids that together encode thefirst polypeptide and the second polypeptide of any of the AICs described herein. In some aspects, the nucleic acid(s) encoding the activatable IL12 fusion protein or the AIC is(are) integrated into the host cell genomic DNA. 99 CYTX-115-PCT 4862-0152WO1 Methods of Producing Activatable IL12 Fusion Proteins or Constructs [00265] Provided herein are methods of producing any of the activatable IL12 fusion proteins or AICs described herein that include: (a) culturing any of the recombinant host cells described herein in a liquid culture medium under conditions sufficient to produce the activatable IL12 fusion protein or AIC; and (b) recovering the activatable IL12 fusion protein or AIC from the host cell and/or the liquid culture medium. [00266] Methods of culturing cells are well known in the art. Cells can be maintained in vitro under conditions that favor cell proliferation, cell differentiation, and cell growth. For example, cells can be cultured by contacting a cell (e.g., any of the cells described herein) with a cell culture medium that includes the necessary growth factors and supplements sufficient to support cell viability and growth. [00267] In some aspects of any of the methods described herein, the method further includes isolating the recovered activatable IL12 fusion proteins or AIC. Non-limiting examples of methods of isolation include: ammonium sulfate precipitation, polyethylene glycol precipitation, size exclusion chromatography, ligand-affinity chromatography, ion-exchange chromatography (e.g., anion or cation), and hydrophobic interaction chromatography. [00268] Compositions and methods described herein may involve use of non-reducing or partially-reducing conditions that allow disulfide bonds to form between the dimerization domains to form and maintain dimerization of the AICs. [00269] In some aspects of any of the methods described herein, the method further includes formulating the activatable IL12 fusion proteins or AICs into a pharmaceutical composition. Various formulations are known in the art and are described herein. Any of the activatable IL12 fusion proteins or AICs described herein can be formulated for any route of administration (e.g., intravenous, intratumoral, subcutaneous, intradermal, oral (e.g., inhalation), transdermal (e.g., topical), transmucosal, or intramuscular). [00270] Also provided herein are activatable IL12 fusion proteins or AICs produced by any of the methods described herein. Also provided are compositions (e.g., pharmaceutical compositions) that include any of the activatable IL12 fusion proteins or AICs produced by any of the methods described herein. Also provided herein are kits that include at least one dose of any of the compositions (e.g., pharmaceutical compositions) described herein. 100 CYTX-115-PCT 4862-0152WO1 [00271] In some aspects, the activatable IL12 fusion proteins or AICs disclosed herein include IL12 mutants. For example, mutants can be used that have advantageous properties compared to the wild type IL12, e.g., exhibit less aggregation compared to wild type IL12 or control activatable IL12 fusion protein or AIC that does not comprise the mutated IL12. In some aspects, the present disclosure provides a method of producing an ACC comprising: culturing a cell comprising a polynucleotide encoding an activatable IL12 fusion protein or AIC herein in a liquid culture medium under conditions sufficient to produce the activatable IL12 fusion protein or AIC; purifying the activatable IL12 fusion protein or AIC using an affinity chromatography, wherein the purified polypeptide has a purity of at least about 40%; and recovering the activatable IL12 fusion protein or AIC from the cell or the liquid culture medium. In some aspects, the purified polypeptide has a purity of at least 50%, 60%, 70%, 75%, 80%, 85%, 90%, or 95%. In non- limiting and exemplary aspects, the polypeptides are subjected to a Protein A affinity chromatography step, followed by preparative size exclusion chromatography (SEC) to prepare purified activatable IL12 fusion proteins. In some aspects, the activatable IL12 fusion proteins are purified to 95% or more monomer as measured by analytical SEC. For example, the disclosures of US11,655,277, WO2023/050006, US Pat. 11,358,999, US Pat. 7,910,564, US Pat. 7,872,107, US Pat.7,833,754, US Pat.11,345,732, WO2017062953A1, US Pat.11,787,864 are incorporated herein by reference in their entireties for all purposes. Methods of Treatment [00272] Provided herein are methods of treating a disease (e.g., a cancer (e.g., any of the cancers described herein)) in a subject including administering a therapeutically effective amount of any of the activatable IL12 fusion proteins or AICs described herein to the subject. [00273] In some aspects, the disorder being treated is a cancer. In some aspects, the disorder being treated is an autoimmune disorder. In some aspects, the disorder being treated is an inflammatory disorder. [00274] As used herein, “subject” refers to any mammal. In some aspects, the subject is a feline (e.g., a cat), a canine (e.g., a dog), an equine (e.g., a horse), a rabbit, a pig, a rodent (e.g., a mouse, a rat, a hamster or a guinea pig), a non-human primate (e.g., a simian (e.g., a monkey (e.g., a baboon, a marmoset), or an ape (e.g., a chimpanzee, a gorilla, an orangutan, or a gibbon)), or a human. In some aspects, the subject is a human. 101 CYTX-115-PCT 4862-0152WO1 [00275] In some aspects, the subject has been previously identified or diagnosed as having the disease (e.g., cancer, including, for example, any of the cancers described herein). [00276] As used herein, “treat” includes reducing the severity, frequency or the number of one or more (e.g., 1, 2, 3, 4, or 5) symptoms or signs of a disease (e.g., a cancer (e.g., any of the cancers described herein)) in the subject (e.g., any of the subjects described herein). In some aspects where the disease is cancer, treating results in reducing cancer growth, inhibiting cancer progression, inhibiting cancer metastasis, or reducing the risk of cancer recurrence in a subject having cancer. [00277] In some aspects of any of the methods described herein, the disease is a cancer. Also provided herein are methods of treating a subject in need thereof (e.g., any of the exemplary subjects described herein or known in the art) that include administering to the subject a therapeutically effective amount of any of the activatable IL12 fusion proteins or AICs described herein or any of the compositions (e.g., pharmaceutical compositions) described herein. [00278] In some aspects of these methods, the subject has been identified or diagnosed as having a cancer. Non-limiting examples of cancer include: solid tumor, hematological tumor, sarcoma, osteosarcoma, glioblastoma, neuroblastoma, melanoma, rhabdomyosarcoma, Ewing sarcoma, osteosarcoma, B-cell neoplasms, multiple myeloma, a lymphoma (e.g., B-cell lymphoma, B-cell non-Hodgkin’s lymphoma, Hodgkin’s lymphoma, cutaneous T-cell lymphoma), a leukemia (e.g., hairy cell leukemia, chronic lymphocytic leukemia (CLL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), acute lymphocytic leukemia (ALL)), myelodysplastic syndromes (MDS), Kaposi sarcoma, retinoblastoma, stomach cancer, urothelial carcinoma, lung cancer, renal cell carcinoma, gastric and esophageal cancer, pancreatic cancer, prostate cancer, brain cancer, colon cancer, bone cancer, lung cancer, breast cancer, colorectal cancer, ovarian cancer, nasopharyngeal adenocarcinoma, non-small cell lung carcinoma (NSCLC), squamous cell head and neck carcinoma, endometrial cancer, bladder cancer, cervical cancer, liver cancer, and hepatocellular carcinoma. In some aspects, the cancer is a lymphoma. In some aspects, the lymphoma is Burkitt’s lymphoma. In some aspects, the subject has been identified or diagnosed as having familial cancer syndromes such as Li Fraumeni Syndrome, Familial Breast- Ovarian Cancer (BRCA1 or BRAC2 mutations) Syndromes, and others. The disclosed methods are also useful in treating non-solid cancers. Exemplary solid tumors include malignancies (e.g., sarcomas, adenocarcinomas, and carcinomas) of the various organ systems, such as those of lung, breast, lymphoid, gastrointestinal (e.g., colon), and genitourinary (e.g., renal, urothelial, or 102 CYTX-115-PCT 4862-0152WO1 testicular tumors) tracts, pharynx, prostate, and ovary. Exemplary adenocarcinomas include colorectal cancers, renal-cell carcinoma, liver cancer, non-small cell carcinoma of the lung, and cancer of the small intestine. [00279] Exemplary cancers described by the National Cancer Institute include: Acute Lymphoblastic Leukemia, Adult; Acute Lymphoblastic Leukemia, Childhood; Acute Myeloid Leukemia, Adult; Adrenocortical Carcinoma; Adrenocortical Carcinoma, Childhood; AIDS- Related Lymphoma; AIDS-Related Malignancies; Anal Cancer; Astrocytoma, Childhood Cerebellar; Astrocytoma, Childhood Cerebral; Bile Duct Cancer, Extrahepatic; Bladder Cancer; Bladder Cancer, Childhood; Bone Cancer, Osteosarcoma/Malignant Fibrous Histiocytoma; Brain Stem Glioma, Childhood; Brain Tumor, Adult; Brain Tumor, Brain Stem Glioma, Childhood; Brain Tumor, Cerebellar Astrocytoma, Childhood; Brain Tumor, Cerebral Astrocytoma/Malignant Glioma, Childhood; Brain Tumor, Ependymoma, Childhood; Brain Tumor, Medulloblastoma, Childhood; Brain Tumor, Supratentorial Primitive Neuroectodermal Tumors, Childhood; Brain Tumor, Visual Pathway and Hypothalamic Glioma, Childhood; Brain Tumor, Childhood (Other); Breast Cancer; Breast Cancer and Pregnancy; Breast Cancer, Childhood; Breast Cancer, Male; Bronchial Adenomas/Carcinoids, Childhood; Carcinoid Tumor, Childhood; Carcinoid Tumor, Gastrointestinal; Carcinoma, Adrenocortical; Carcinoma, Islet Cell; Carcinoma of Unknown Primary; Central Nervous System Lymphoma, Primary; Cerebellar Astrocytoma, Childhood; Cerebral Astrocytoma/Malignant Glioma, Childhood; Cervical Cancer; Childhood Cancers; Chronic Lymphocytic Leukemia; Chronic Myelogenous Leukemia; Chronic Myeloproliferative Disorders; Clear Cell Sarcoma of Tendon Sheaths; Colon Cancer; Colorectal Cancer, Childhood; Cutaneous T-Cell Lymphoma; Endometrial Cancer; Ependymoma, Childhood; Epithelial Cancer, Ovarian; Esophageal Cancer; Esophageal Cancer, Childhood; Ewing’s Family of Tumors; Extracranial Germ Cell Tumor, Childhood; Extragonadal Germ Cell Tumor; Extrahepatic Bile Duct Cancer; Eye Cancer, Intraocular Melanoma; Eye Cancer, Retinoblastoma; Gallbladder Cancer; Gastric (Stomach) Cancer; Gastric (Stomach) Cancer, Childhood; Gastrointestinal Carcinoid Tumor; Germ Cell Tumor, Extracranial, Childhood; Germ Cell Tumor, Extragonadal; Germ Cell Tumor, Ovarian; Gestational Trophoblastic Tumor; Glioma, Childhood Brain Stem; Glioma, Childhood Visual Pathway and Hypothalamic; Hairy Cell Leukemia; Head and Neck Cancer; Hepatocellular (Liver) Cancer, Adult (Primary); Hepatocellular (Liver) Cancer, Childhood (Primary); Hodgkin’s Lymphoma, Adult; Hodgkin’s Lymphoma, Childhood; 103 CYTX-115-PCT 4862-0152WO1 Hodgkin’s Lymphoma During Pregnancy; Hypopharyngeal Cancer; Hypothalamic and Visual Pathway Glioma, Childhood; Intraocular Melanoma; Islet Cell Carcinoma (Endocrine Pancreas); Kaposi’s Sarcoma; Kidney Cancer; Laryngeal Cancer; Laryngeal Cancer, Childhood; Leukemia, Acute Lymphoblastic, Adult; Leukemia, Acute Lymphoblastic, Childhood; Leukemia, Acute Myeloid, Adult; Leukemia, Acute Myeloid, Childhood; Leukemia, Chronic Lymphocytic; Leukemia, Chronic Myelogenous; Leukemia, Hairy Cell; Lip and Oral Cavity Cancer; Liver Cancer, Adult (Primary); Liver Cancer, Childhood (Primary); Lung Cancer, Non-Small Cell; Lung Cancer, Small Cell; Lymphoblastic Leukemia, Adult Acute; Lymphoblastic Leukemia, Childhood Acute; Lymphocytic Leukemia, Chronic; Lymphoma, AIDS-Related; Lymphoma, Central Nervous System (Primary); Lymphoma, Cutaneous T-Cell; Lymphoma, Hodgkin’s, Adult; Lymphoma, Hodgkin’s, Childhood; Lymphoma, Hodgkin’s During Pregnancy; Lymphoma, Non- Hodgkin’s, Adult; Lymphoma, Non-Hodgkin’s, Childhood; Lymphoma, Non-Hodgkin’s During Pregnancy; Lymphoma, Primary Central Nervous System; Macroglobulinemia, Waldenstrom’s; Male Breast Cancer; Malignant Mesothelioma, Adult; Malignant Mesothelioma, Childhood; Malignant Thymoma; Medulloblastoma, Childhood; Melanoma; Melanoma, Intraocular; Merkel Cell Carcinoma; Mesothelioma, Malignant; Metastatic Squamous Neck Cancer with Occult Primary; Multiple Endocrine Neoplasia Syndrome, Childhood; Multiple Myeloma/Plasma Cell Neoplasm; Mycosis Fungoides; Myelodysplastic Syndromes; Myelogenous Leukemia, Chronic; Myeloid Leukemia, Childhood Acute; Myeloma, Multiple; Myeloproliferative Disorders, Chronic; Nasal Cavity and Paranasal Sinus Cancer; Nasopharyngeal Cancer; Nasopharyngeal Cancer, Childhood; Neuroblastoma; Non-Hodgkin’s Lymphoma, Adult; Non- Hodgkin’s Lymphoma, Childhood; Non-Hodgkin’s Lymphoma During Pregnancy; Non-Small Cell Lung Cancer; Oral Cancer, Childhood; Oral Cavity and Lip Cancer; Oropharyngeal Cancer; Osteosarcoma/Malignant Fibrous Histiocytoma of Bone; Ovarian Cancer, Childhood; Ovarian Epithelial Cancer; Ovarian Germ Cell Tumor; Ovarian Low Malignant Potential Tumor; Pancreatic Cancer; Pancreatic Cancer, Childhood; Pancreatic Cancer, Islet Cell; Paranasal Sinus and Nasal Cavity Cancer; Parathyroid Cancer; Penile Cancer; Pheochromocytoma; Pineal and Supratentorial Primitive Neuroectodermal Tumors, Childhood; Pituitary Tumor; Plasma Cell Neoplasm/Multiple Myeloma; Pleuropulmonary Blastoma; Pregnancy and Breast Cancer; Pregnancy and Hodgkin’s Lymphoma; Pregnancy and Non-Hodgkin’s Lymphoma; Primary Central Nervous System Lymphoma; Primary Liver Cancer, Adult; Primary Liver Cancer, 104 CYTX-115-PCT 4862-0152WO1 Childhood; Prostate Cancer; Rectal Cancer; Renal Cell (Kidney) Cancer; Renal Cell Cancer, Childhood; Renal Pelvis and Ureter, Transitional Cell Cancer; Retinoblastoma; Rhabdomyosarcoma, Childhood; Salivary Gland Cancer; Salivary Gland Cancer, Childhood; Sarcoma, Ewing’s Family of Tumors; Sarcoma, Kaposi’s; Sarcoma (Osteosarcoma)/Malignant Fibrous Histiocytoma of Bone; Sarcoma, Rhabdomyosarcoma, Childhood; Sarcoma, Soft Tissue, Adult; Sarcoma, Soft Tissue, Childhood; Sezary Syndrome; Skin Cancer; Skin Cancer, Childhood; Skin Cancer (Melanoma); Skin Carcinoma, Merkel Cell; Small Cell Lung Cancer; Small Intestine Cancer; Soft Tissue Sarcoma, Adult; Soft Tissue Sarcoma, Childhood; Squamous Neck Cancer with Occult Primary, Metastatic; Stomach (Gastric) Cancer; Stomach (Gastric) Cancer, Childhood; Supratentorial Primitive Neuroectodermal Tumors, Childhood; T- Cell Lymphoma, Cutaneous; Testicular Cancer; Thymoma, Childhood; Thymoma, Malignant; Thyroid Cancer; Thyroid Cancer, Childhood; Transitional Cell Cancer of the Renal Pelvis and Ureter; Trophoblastic Tumor, Gestational; Unknown Primary Site, Cancer of, Childhood; Unusual Cancers of Childhood; Ureter and Renal Pelvis, Transitional Cell Cancer; Urethral Cancer; Uterine Sarcoma; Vaginal Cancer; Visual Pathway and Hypothalamic Glioma, Childhood; Vulvar Cancer; Waldenstrom’s Macro globulinemia; and Wilms’ Tumor. [00280] Further exemplary cancers include diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL). [00281] Metastases of the aforementioned cancers can also be treated or prevented in accordance with the methods described herein. [00282] In some aspects, these methods can result in a reduction in the number, severity, or frequency of one or more symptoms of the cancer in the subject (e.g., as compared to the number, severity, or frequency of the one or more symptoms of the cancer in the subject prior to treatment). [00283] In some aspects of any of the methods described herein, the methods further include administering to a subject an additional therapeutic agent (e.g., one or more of the therapeutic agents listed in Table 2). Table 2. Additional Therapeutic Agents Antibody Trade Name (antibody name) Target 105 CYTX-115-PCT 4862-0152WO1 Bexxar™ (tositumomab) CD20 Gaz va™ (obinutuzumab) CD20 106 CYTX-115-PCT 4862-0152WO1 (depatuxizumab mafodotin) EGFR (futuximab:modotuximab) EGFR 107 CYTX-115-PCT 4862-0152WO1 (teprotumumab) IGF1R Simulect™ (basiliximab) IL2R ) 108 CYTX-115-PCT 4862-0152WO1 CBT-501 (genolimzumab PD1 ABBV181 (budi alimab) PD1 109 CYTX-115-PCT 4862-0152WO1 Enbrel™ (etanercept) TNF-R (ma atumumab) TRAIL-R1 Compositions/Kits [00284] The present disclosure further provides a composition comprising an activatable IL12 fusion protein or AIC of the present disclosure or an encoding nucleic acid thereof. In some aspects, the composition comprises water and an activatable IL12 fusion protein or AIC of the present invention. In other aspects, the composition comprises water and any of the nucleic acids of the present disclosure. Such compositions are useful for transfecting cells. Also provided herein are pharmaceutical compositions that comprise any of the activatable IL12 fusion proteins or AICs described herein and one or more (e.g., 1, 2, 3, 4, or 5) pharmaceutically acceptable carriers (e.g., any of the pharmaceutically acceptable carriers described herein), diluents, or excipients. [00285] In some aspects, the compositions (e.g. pharmaceutical compositions) that include any of the activatable IL12 fusion proteins or AICs described herein can be disposed in a sterile vial or a pre-loaded syringe. [00286] In some aspects, the compositions (e.g. pharmaceutical compositions) that include any of the activatable IL12 fusion proteins or AICs described herein can be formulated for different routes of administration (e.g., intravenous, subcutaneous, intramuscular, intraperitoneal, or intratumoral). [00287] In some aspects, any of the pharmaceutical compositions described herein can include one or more buffers (e.g., a neutral-buffered saline, a phosphate-buffered saline (PBS), amino acids (e.g., glycine), one or more carbohydrates (e.g., glucose, mannose, sucrose, dextran, or mannitol), one or more antioxidants, one or more chelating agents (e.g., EDTA or glutathione), one or more preservatives, and/or a pharmaceutically acceptable carrier (e.g., bacteriostatic water, PBS, or saline). [00288] As used herein, the phrase “pharmaceutically acceptable carrier” refers to any and all solvents, dispersion media, coatings, antibacterial agents, antimicrobial agents, isotonic and 110 CYTX-115-PCT 4862-0152WO1 absorption delaying agents, and the like, compatible with pharmaceutical administration. Suitable carriers include, but are not limited to: water, saline, ringer’s solutions, dextrose solution, and about 5% human serum albumin. [00289] In some aspects of any of the pharmaceutical compositions described herein, any of the activatable IL12 fusion proteins or AICs described herein are prepared with carriers that protect against rapid elimination from the body, e.g., sustained and controlled release formulations, including implants and microencapsulated delivery systems. Biodegradable, biocompatible polymers can be used, e.g., ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Methods for preparation of such pharmaceutical compositions and formulations are apparent to those skilled in the art. [00290] In another aspect, the present disclosure also provides a composition (e.g., a composition produced during the process of making the activatable IL12 fusion protein or AIC), in which the purified activatable IL12 fusion protein or AIC is at least 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, or 95% pure. [00291] Also provided herein are kits that include any of the activatable IL12 fusion proteins or AICs described herein, any of the compositions that include any of the activatable IL12 fusion proteins or AICs described herein, or any of the pharmaceutical compositions that include any of the activatable IL12 fusion proteins or AICs described herein. Also provided are kits that include one or more second therapeutic agent(s) selected from Table 2 in addition to activatable IL12 fusion proteins or AICs described herein. The second therapeutic agent(s) may be provided in a dosage administration form that is separate from the activatable IL12 fusion proteins or AICs. Alternatively, the second therapeutic agent(s) may be formulated together with the activatable IL12 fusion proteins or AICs. In some aspects, the kit comprises (1) an activatable IL12 fusion protein or AIC comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 1–54, and (2) a second therapeutic agent selected from Table 2. [00292] Any of the kits described herein can include instructions for using any of the compositions (e.g., pharmaceutical compositions) and/or any of the activatable IL12 fusion proteins or AICs described herein. In some aspects, the kits can include instructions for performing any of the methods described herein. In some aspects, the kits can include at least one dose of any of the compositions (e.g., pharmaceutical compositions) described herein. In some aspects, the kits can provide a syringe for administering any of the pharmaceutical compositions described herein. 111 CYTX-115-PCT 4862-0152WO1 EXAMPLES [00293] The invention is further described in the following examples, which do not limit the scope of the invention described in the claims. Example 1: Production of Activatable IL12 Fusion Proteins and Constructs [00294] Activatable IL12 fusion proteins and AICs containing human IL12 (FIGs. 1A–1K) were prepared by recombinant methods. The polypeptides were prepared by transforming a host cell with a polynucleotide encoding the sequences of SEQ ID NOs: 1–54 and 1532, 1533, 1536, 1537, 1540, 1541, 1544, 1545, 1548, 1550, 1552, 1553, 1556, 1557, 1560, 1561, 1564, 1565, 1568, 1569, 1572, 1573, 1576, 1577, 1580, 1581, 1584, 1585, 1588, 1590, 1592, 1593, 1596, 1597, 1600, 1601, 1604, 1605, 1608, 1609, 1612, 1613, 1616, 1617, 1620, 1621, 1624, 1625, 1628, 1629, 1632, and 1633. followed by cultivation of the resulting recombinant host cells so as to express the polypeptides having the sequences of SEQ ID NOs: 1–54 and 1532, 1533, 1536, 1537, 1540, 1541, 1544, 1545, 1548, 1550, 1552, 1553, 1556, 1557, 1560, 1561, 1564, 1565, 1568, 1569, 1572, 1573, 1576, 1577, 1580, 1581, 1584, 1585, 1588, 1590, 1592, 1593, 1596, 1597, 1600, 1601, 1604, 1605, 1608, 1609, 1612, 1613, 1616, 1617, 1620, 1621, 1624, 1625, 1628, 1629, 1632, and 1633 in various cultures. Supernatant harvested from recombinant host cells expressing the polypeptides may be subjected to a Protein A affinity chromatography step, followed by preparative size exclusion chromatography (SEC) to prepare purified activatable IL12 fusion proteins. The purified products can be confirmed to be about 95% or more monomer by analytical SEC. Table 6 provides a description of illustrative AICs. Table 6. Format SEQ ID 112 CYTX-115-PCT 4862-0152WO1 ProC1914 15, 16 1B Hu Peptide (SEQ ID CM1 (SEQ ID NO: 144), NO: 294) CM2 (SEQ ID NO: 1278) : : 113 CYTX-115-PCT 4862-0152WO1 Peptide (SEQ ID CM1 (SEQ ID NO: 246); ProC2702 45, 46 1D Hu CM2, CD3 (SEQ ID NO: NO: 303) , : : 114 CYTX-115-PCT 4862-0152WO1 ProC5866 1640, 1H Chim scFv (SEQ ID CM1, CM2 (SEQ ID NO: 1641 NO: 289) 428) D D D D D 115 CYTX-115-PCT 4862-0152WO1 Split scFv, with CM1, CM2 (SEQ ID NO: ProC5882 1660, Hu CM of SEQ ID 428) : D D D D Example 2: Protease activation 116 CYTX-115-PCT 4862-0152WO1 [00295] To release the MM or the dimerization domain, activatable IL12 fusion proteins or AICs were treated overnight at 37°C with recombinant human matrix metalloprotease 2 (MMP2), or MMP9, or MMP14 or urokinase plasminogen activator (uPA). A cocktail of protease inhibitors was added to neutralize the proteases prior to testing for activity. Cleavage of CMs with protease at the expected sites was confirmed by electrophoresis (FIGs. 2–5 and FIGs. 11-17). Example 3: In vitro evaluation of IL12 activity in reporter assay [00296] The activities of activatable IL12 constructs were tested in vitro using IL12 responsive HEK293 cells. The IL12-responsive HEK293 cells were generated by stable transfection with the human IL12Rb1 and IL12Rb2 genes, along with the genes of the IL12 signaling pathway. The cells also feature an STAT4-inducible secreted embryonic alkaline phosphatase (SEAP) reporter gene. To maintain transgene expression, cells were cultured in DMEM GlutaMaxTM media supplemented with 10% FBS, Pen/Strep, 10 µg/mL Puromycin, and 100 µg/mL of NormocinTM. The addition of IL12 to these cells activates the STAT4 and subsequently induces the production of SEAP which can be readily assessed in the supernatant using QUANTI-Blue solution, a colorimetric detection for alkaline phosphatase activity. [00297] IL12-responsive HEK293 cells were prepared at a concentration of 106 cells/mL in DMEM media supplemented with 10% FBS and 50 μL aliquots were pipetted into wells of a white flat-bottom 96-well plate (50,000 cells/well). The tested constructs were diluted in DMEM media supplemented with 10% FBS. Duplicate of three-fold serial dilutions were prepared from which 50 μL was added to each well. After 20–24 hours of incubation at 37°C, 20 μL of supernatant of the induced reporter cells was transferred to wells of aflat-bottom 96-well plate. 180 µL of resuspended QUANTI-Blue solution was added per well. Following incubation of the plate at 37°C incubator for 0.5–1.5 hrs, the SEAP levels were measured using a spectrophotometer at 620 nm. Dose-response curves were generated and EC50 values were obtained by sigmoidalfit non-linear regression using Graph Pad Prism software. [00298] FIGs.6–9 show IL12 activity of constructs SEQ ID NOs.: 7 to 52 and SEQ ID NO: 1662 and 1663 (ProC670/ProC671) in HEK-Blue IL12 reporter assay. EC50 values are summarized in Table 3. The activity of ProC1910, ProC1911, ProC1912, ProC1913, ProC1914, and ProC1915 was reduced 2.5- to 6-fold compared to unmasked counterpart ProC670 (Figure 1F). The activity of ProC1977, ProC1978, ProC1979, ProC1980, ProC1981, ProC1982, ProC2695, ProC2696, 117 CYTX-115-PCT 4862-0152WO1 ProC2697, ProC2698, ProC2699, ProC2700, ProC2701, ProC2702, ProC2703, ProC2704, and ProC2705 was 1- to 4-fold reduced compared to unmasked counterpart ProC671 (Figure 1G). Table 3. EC50: HEK-Blue Reporter Assay rhIL12 ProC670 ProC1910 ProC1911 ProC1912 ProC1913 ProC1914 ProC1915 EC50 5379 259 1446 7256 8274 1301 7692 9923 00 Example 4: In vitro characterization of exemplary IL12 constructs [00299] In one reporter assay, the activities of certain IL12 constructs ProC2020, ProC1726, and ProC1727 were evaluated before and after activation with protease (FIG. 10). The activity of ProC2020 was reduced at least 250-fold as compared to recombinant human IL12 (rhIL12) (PeproTech, Catalog #200-12H), and at least 150-fold as compared to the activated ProC2020. The activity of ProC1726 was reduced at least 150-fold as compared to rhIL12 and at least 50-fold as compared to the activated ProC1726. The activity of ProC1727 was reduced at least 40-fold as compared to rhIL12 and at least 15-fold as compared to the activated ProC1727. EC50 values for rhIL12, ProC2020, ProC1726, ProC1727, ProC2020+MMP14, ProC1726+MMP14, ProC1727+MMP14 are provided below in Table 4. [00300] In several other reporter assays, the activities of certain IL12 constructs ProC5145, ProC5146, ProC5147, ProC5148, ProC5150, ProC5152, ProC5153, ProC5333, ProC5334, ProC5584, ProC5585, ProC5586, ProC5587, ProC5745, ProC5746, ProC5747 and ProC5748 were evaluated before and after activation with protease (FIGs.18–24). EC50 values for the intact and activated molecules are provided below in Table 5. [00301] These observations, i.e., that the AICs have high masking efficiency compared to both recombinant human IL12 and activated (cleaved) AIC molecules, indicate that there is an enhanced masking effect so as to prevent IL12 activity in the environment of healthy cells associated with 118 CYTX-115-PCT 4862-0152WO1 IL12 toxicity, and to enhance IL12 activity in diseased tissues with high concentrations of proteases. Table 4. EC50: HEK-Blue Reporter Assay EC50 (pM) hIL 12 2344 Table 5. EC50 values o ntact and act vated IL12 AICs n HEK-B ue Reporter Assay Intact Activated by Activated by 119 CYTX-115-PCT 4862-0152WO1 ProC5746 10370 22.86 ProC5747 12760 4830 Example 5: In vivo evaluation of exemplary IL12 constructs [00302] To evaluate the in vivo tolerability and anti-tumor activity of the IL-12 AICs, MC38 tumor-bearing mice were treated with IL12 AICs via intravenous administration on study day 1, day 4, day 8 and day 11. Mice treated with ProC5152 and ProC5153 at 0.3 mg/kg had reduced tumor volume relative to the vehicle control (FIG.25). Plasma samples collected on day 2 and day 5 were evaluated for GM-CSF, IFN-γ, IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12(p70) and TNFα levels (FIGs. 26-27). ALT and AST levels were also assessed as measures of toxicity on day 12 (FIG. 28). Overall, the exemplary IL12 AICs demonstrated strong anti-tumor activity and were well tolerated at the efficacious dose level. [00303] Sequences for exemplary Activatable IL12 fusion proteins and AICs are shown in Table 7, below. The Italicized text corresponds to IL12 p40 and p35, the bold text corresponds to Brikianumab VL and VH, the underlined text corresponds to substrate, and the italic and bold text corresponds to the IL12RB2 ECD fragment. Table 7 SEQ Activatable IL12 Sequence ID fusion protein or T S S F L I G A N 120 CYTX-115-PCT 4862-0152WO1 DQRPSGVPDRFSGSKSGTSASLAITGLQAEDEADYYCQ SYDRYTHPALLFGTGTKVTVLGGGGSGSGGSGGGGSQ R V T E S K T S S P V Y M G S S T 121 CYTX-115-PCT 4862-0152WO1 IDRVMSYLNASDHQSRSGGSESKYGPPCPPCPAPEFEG GPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQF C P C T S S P SI F E Q G S V P E 122 CYTX-115-PCT 4862-0152WO1 7 ProC1910 QSGQLHCRKDPPHICNHNGSSGGSISSGLLSSGSGGSIW polypeptide 1 ELKKDVYVVELDWYPDAPGEMVVLTCDTPEEDGITWT H S D L N T C E S K S S P SI F E Q 123 CYTX-115-PCT 4862-0152WO1 VYTLPPCQEEMTKNQVSLWCLVKGFYPSDIAVEWESN GQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGN E S K S S P SI F E Q E S K 124 CYTX-115-PCT 4862-0152WO1 13 ProC1913 QSGQRGQGPCITYCRHPVNGSSGGSISSGLLSSGSGGSI polypeptide 1 WELKKDVYVVELDWYPDAPGEMVVLTCDTPEEDGIT V S S P SI F E Q E S K S S P SI F E Q 125 CYTX-115-PCT 4862-0152WO1 VYTLPPCQEEMTKNQVSLWCLVKGFYPSDIAVEWESN GQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGN E S K S S P SI F E Q E S K 126 CYTX-115-PCT 4862-0152WO1 19 ProC1977 QSGQLHCRKDPPHICNHNGSSGGSISSGLLSSGSGGSIW polypeptide 1 ELKKDVYVVELDWYPDAPGEMVVLTCDTPEEDGITWT H S D V T L S F E F Q E S S P V Y M 127 CYTX-115-PCT 4862-0152WO1 22 ProC1978 RNLPVATPDPGMFPCLHHSQNLLRAVSNMLQKARQTL polypeptide 2 EFYPCTSEEIDHEDITKDKTSTVEACLPLELTKNESCLNS F E F Q E S S P V Y M L S F E F Q E 128 CYTX-115-PCT 4862-0152WO1 MVDAVHKLKYENYTSSFFIRDIIKPDPPKNLQLKPLKNS RQVEVSWEYPDTWSTPHSYFSLTFCVQVQGKSKREKK S P V Y M L S F E F Q E S S P V Y M L S F E F 129 CYTX-115-PCT 4862-0152WO1 KEYKCKVSNKGLPSSIEKTISKAKGQPREPQVCTLPPSQ EEMTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYK E S S P V Y M L S F E F Q E I S S P V Y M 130 CYTX-115-PCT 4862-0152WO1 TKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEAL L S F E F Q E W T H S D V T L S F E F Q E 131 CYTX-115-PCT 4862-0152WO1 35 ProC2697 QSGQSSCCWGWRKCCPREGGSSGGSLSGRSNIGSGGSI polypeptide 1 WELKKDVYVVELDWYPDAPGEMVVLTCDTPEEDGIT V S S P V Y M L S F E F Q E I S S P V Y M 132 CYTX-115-PCT 4862-0152WO1 38 ProC2698 RNLPVATPDPGMFPCLHHSQNLLRAVSNMLQKARQTL polypeptide 2 EFYPCTSEEIDHEDITKDKTSTVEACLPLELTKNESCLNS F E F Q E I S S P V Y M L S F E F Q E L S G 133 CYTX-115-PCT 4862-0152WO1 AVHKLKYENYTSSFFIRDIIKPDPPKNLQLKPLKNSRQV EVSWEYPDTWSTPHSYFSLTFCVQVQGKSKREKKDRV C V T L S F E F Q E S S P V Y M L S F E F 134 CYTX-115-PCT 4862-0152WO1 KEYKCKVSNKGLPSSIEKTISKAKGQPREPQVCTLPPSQ EEMTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYK E I S S P V Y M L S F E F Q E I S S P V Y M 135 CYTX-115-PCT 4862-0152WO1 TKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEAL L S F E F Q E I S S P V Y M L S F E F Q E 136 CYTX-115-PCT 4862-0152WO1 51 ProC2705 QSGQSNKKACMVFCSRWACGSSGGSLSGRSNIGSGGSI polypeptide 1 WELKKDVYVVELDWYPDAPGEMVVLTCDTPEEDGIT V S S P V Y M L S F E F Q E G S S E K W S 137 CYTX-115-PCT 4862-0152WO1 LNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLP PCQEEMTKNQVSLWCLVKGFYPSDIAVEWESNGQPEN V L S F E F Q E T S S P SI F E Q T 138 CYTX-115-PCT 4862-0152WO1 MVDAVHKLKYENYTSSFFIRDIIKPDPPKNLQLKPLKNS RQVEVSWEYPDTWSTPHSYFSLTFCVQVQGKSKREKK S P SI F E Q T S S P SI F E Q T S S P SI 139 CYTX-115-PCT 4862-0152WO1 YEDLKMYQVEFKTMNAKLLMDPKRQIFLDQNMLAVI DELMQALNFNSETVPQKSSLEEPDFYKTKIKLCILLHAF E Q T S S P SI F E Q T S S P SI F E Q 140 CYTX-115-PCT 4862-0152WO1 VYTLPPCQEEMTKNQVSLWCLVKGFYPSDIAVEWESN GQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGN T S S P V Y M T S S P V Y M T S S P V Y M 141 CYTX-115-PCT 4862-0152WO1 PVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEAL HNRFTQKSLSLSLG T S S P V Y M T S S P V Y M T S S P V Y M 142 CYTX-115-PCT 4862-0152WO1 PVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEAL HNRFTQKSLSLSLG T S S P V Y M T S S P V Y M T S S P V Y M 143 CYTX-115-PCT 4862-0152WO1 PVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEAL HNRFTQKSLSLSLG T S S P V Y M T S S P V Y M T S S P V Y M 144 CYTX-115-PCT 4862-0152WO1 PVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEAL HNRFTQKSLSLSLG T S S P V Y M T S S P V Y M T S S P V Y M 145 CYTX-115-PCT 4862-0152WO1 PVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEAL HNRFTQKSLSLSLG T S S P V Y M T S S P V Y M L T G S E S N L R 146 CYTX-115-PCT 4862-0152WO1 TPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKP REEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKG W F L Y L E G P S V G a a c c c a g t c g g c a T C G T A C A 147 CYTX-115-PCT 4862-0152WO1 GAGAGACAAGCAGCACAACAAGAGGCAGCTGTCTG CCTCCTCAGAAAACCAGCCTGATGATGACCCTGTGC G G T G T G C T T T C C G C G T G G T 148 CYTX-115-PCT 4862-0152WO1 GGAATGGGTAGCGTTCATTCGATACGATGGGAGTAA CAAGTACTATGCCGACTCAGTGAAAGGACGATTTAC C A A A C T L T G S E S N L R 149 CYTX-115-PCT 4862-0152WO1 LPSSIEKTISKAKGQPREPQVYTLPPCQEEMTKNQVSLW CLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSF L Y L E G C V P E G a a c c c a g t c g g c a T C G T A C A G 150 CYTX-115-PCT 4862-0152WO1 ACCGAGTTCCAGGCCATCAACGCCGCTCTGCAGAAC CACAACCACCAGCAGATCATCCTGGACAAGGGCATG C T G T G C T T T C C G C G T G G T C 151 CYTX-115-PCT 4862-0152WO1 CAAATGAACAGCCTTCGAGCCGAGGACACTGCAGTA TACTACTGTAAAACGCACGGGTCACACGACAATTGG C A C L T G S E S N L R W F L 152 CYTX-115-PCT 4862-0152WO1 1541 ProC5147 chain 2 QSVLTQPPSVSGAPGQRVTISCSGSRSNIGSNTVKWY amino acid QQLPGTAPKLLIYYNDQRPSGVPDRFSGSKSGTSASL E S P V G a a c c c a g t c g g c a T C G T A C A G G T G 153 CYTX-115-PCT 4862-0152WO1 TGCATCCTGCTGCACGCCTTCAGCACCAGAGTGGTC ACCATCAACAGAGTGATGGGCTACCTGTCCAGTGCT A T G C T T T C C G C G T G G T C A G G 154 CYTX-115-PCT 4862-0152WO1 GGTCAGGTCCACCGTGTCCGCCCTGTCCAGCACCGG AATTCGAGGGTGGTCCCAGTGTTTTTCTTTTTCCGCC A C L T G S E S N L R W F L Y L E 155 CYTX-115-PCT 4862-0152WO1 DTAVYYCKTHGSHDNWGQGTMVTVSSGGGGSGGG SGGSGSPWGLSGRSGGSGPPCPPCPAPEFEGGPSVFLFP G E L G a a c c c a g t c g g c a T C G T A C A G G T G T G 156 CYTX-115-PCT 4862-0152WO1 GACCCCAGAGGTAACCTGCGTCGTCGTGGATGTTAG TCAGGAAGATCCCGAAGTTCAGTTCAATTGGTACGT C T T T C C G C G T G G T C A C 157 CYTX-115-PCT 4862-0152WO1 TTCTACTTATAGGGTCGTCTCCGTCTTGACAGTGTTG CATCAAGATTGGCTGAATGGCAAAGAATATAAGTGT A L T G S E S N G Q T S Y V I Y G G 158 CYTX-115-PCT 4862-0152WO1 AACTGGACTGGTATCCCGATGCTCCTGGCGAGATGG TGGTGCTGACCTGCGATACCCCTGAAGAGGACGGCA T A A T C G T C C C A A G G G A T A C 159 CYTX-115-PCT 4862-0152WO1 GTAAGTGGTGCTCCTGGCCAGCGCGTTACAATAAGC TGTTCAGGGAGTCGATCTAATATCGGATCAAATACT C A G A C C a T c C C T C C C L T G 160 CYTX-115-PCT 4862-0152WO1 DNKEYEYSVECQEDSACPAAEESLPIEVMVDAVHKLKYEN YTSSFFIRDIIKPDPPKNLQLKPLKNSRQVEVSWEYPDTWS S E S N G Q T S Y S V I P G G A T A A T C G T C 161 CYTX-115-PCT 4862-0152WO1 AGACAGGTGGAAGTGTCCTGGGAGTACCCCGACACC TGGTCTACACCCCACAGCTACTTCAGCCTGACCTTTT C A A G G G A T A C C A G A C 162 CYTX-115-PCT 4862-0152WO1 GGCAGCCACGACAATTGGGGCCAGGGCACAATGGTC ACAGTGTCTAGCGGCGGCAGCCCTTGGGGGTTGCAC T T A T G A A L T G S E S N G Q T S Y 163 CYTX-115-PCT 4862-0152WO1 GPPCPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVTCV VVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNS I Y E S K G G A T A A T C G T C C C A A G 164 CYTX-115-PCT 4862-0152WO1 GGAACTGCACAAAAACGAAAGTTGTCTGGCGACTAG AGAGACCAGTTCAACTACCCGGGGAAGTTGCTTGCC G A T A C C A G A C C a T c C C 165 CYTX-115-PCT 4862-0152WO1 ATGCCAAGAAGAGATGACCAAGAATCAGGTGTCCCT GTGGTGCCTGGTCAAGGGCTTCTACCCTTCCGATATC C C A A C L T G S E S N G Q T 166 CYTX-115-PCT 4862-0152WO1 APKLLIYYNDQRPSGVPDRFSGSKSGTSASLAITGLQ AEDEADYYCQSYDRYTHPALLFGTGTKVTVLGGGG S Y S V I Y E S K G G A T A A T C G T C C C A A 167 CYTX-115-PCT 4862-0152WO1 GGCGGAGGTGGAAGCGGCGGAGGCGGATCTAGAGT TATCCCAGTAAGCGGGCCGGCACGGTGTCTCTCCCA T G G G A T A C C A G A C C a T 168 CYTX-115-PCT 4862-0152WO1 TGGACGGCGTGGAAGTGCACAACGCCAAGACCAAGc ctagagaggaacagttcaacAGCACCTACAGAGTGGTGTCCGT A C C T C C C A A C L T G S E 169 CYTX-115-PCT 4862-0152WO1 DIDHEDITRDQTSTLKTCLPLELHKNESCLATRETSSTTRGS CLPPQKTSLMMTLCLGSIYEDLKMYQTEFQAINAALQNHN G P S Y V S P E S K G G A T A A T C G T C C 170 CYTX-115-PCT 4862-0152WO1 TGGTCTACACCCCACAGCTACTTCAGCCTGACCTTTT GCGTGCAAGTGCAGGGCAAGTCCAAGCGCGAGAAA C A A G G G A T A C G A T A G T 171 CYTX-115-PCT 4862-0152WO1 GTCTAGCGGCGGCAGCCCTTGGGGACTGTCTGGAAG AAGCGGTGGCAGCGGCCCTCCTTGTcctccatgtcctgctccag T C G c A A C C A A A C L T 172 CYTX-115-PCT 4862-0152WO1 CWWLTTISTDLTFSVKSSRGSSDPQGVTCGAATLSAERVRG DNKEYEYSVECQEDSACPAAEESLPIEVMVDAVHKLKYEN S S E S N G P S Y V S P E S K G G A T A A T 173 CYTX-115-PCT 4862-0152WO1 CAGCGTGGAATGCCAAGAGGACAGCGCCTGTCCAGC CGCCGAAGAGTCTCTGCCTATCGAAGTGATGGTGGA G T C C C A A G G G A T A C G A T 174 CYTX-115-PCT 4862-0152WO1 TGGCAAAGGACTTGAGTGGGTCGCCTTCATCAGATA CGACGGCTCCAACAAGTACTACGCCGACTCCGTGAA A G T g T C G c A A C C A A A C 175 CYTX-115-PCT 4862-0152WO1 AGCGTGATGCACGAAGCACTGCACAACcgcttcACGCA GAAAAGCCTGTCCCTGAGCCTGGGCAAATGA L T G S S L S K S A R S S T E S K G G A T 176 CYTX-115-PCT 4862-0152WO1 AGAAAGAGGATGGCATTTGGAGCACCGACATCCTGA AGGACCAGAAAGAGCCCAAGAACAAGACCTTCCTG A T C G T C C C A A t a ct tg t tc c gt c c G G A G G T 177 CYTX-115-PCT 4862-0152WO1 TAGCAGCTATGGCATGCACTGGGTCCGACAGGCCCC TGGCAAAGGACTTGAGTGGGTCGCCTTCATCAGATA A A G T G T A G C T T A A G A A C 178 CYTX-115-PCT 4862-0152WO1 AGCGTGATGCACGAAGCACTGCACAACcgcttcACGCA GAAAAGCCTGTCCCTGAGCCTGGGCAAATGA L T G S E S N M T K L K E S K G a a c c c a g t c g g c a 179 CYTX-115-PCT 4862-0152WO1 gcagttcatggagtgagtgggcctctgtaccttgcagtGGTGGCGGAGGAT CTGGCGGAGGTGGAAGCGGCGGAGGCGGATCTAGA C C G T C T A G T A C C A 180 CYTX-115-PCT 4862-0152WO1 AGTAGAAGTTCATAACGCCAAAACAAAACCACGCGA GGAACAATTCAATTCTACTTATAGGGTCGTCTCCGTC L T G S E S N A L S S A W T P S E S 181 CYTX-115-PCT 4862-0152WO1 IEKTISKAKGQPREPQVCTLPPSQEEMTKNQVSLSCAVK GFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVS G G A T A A T C G T C C C A A G G G A T 182 CYTX-115-PCT 4862-0152WO1 ATCTTGTTGCACGCCTTTAGCACTCGAGTAGTAACGA TCAACAGAGTGATGGGATACTTGTCCTCAGCTGGAG G G G C G T C C C G T G A G A C G a 183 CYTX-115-PCT 4862-0152WO1 1579 ProC5585 chain 2 atgagagcctggatctttttcctgctgtgcctggcagggcgcgcactggctgagTCA DNA sequence AAATATGGTCCACCGTGTCCGCCCTGTCCAGCACCG A A C L T G S E S N P S Y L V 184 CYTX-115-PCT 4862-0152WO1 KGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLY SRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLS E S K G G A T A A T C G T C C C A A G G G 185 CYTX-115-PCT 4862-0152WO1 GGTTCCATTTATGAGGACCTGAAGATGTACCAGACA GAGTTTCAAGCTATTAACGCGGCATTGCAAAACCAC A T A C G T T A G T g ct C G A T T C 186 CYTX-115-PCT 4862-0152WO1 ACTACAAGACCACACCTCCTGTGCTGGACAGCGACG GCTCATTCTTCCTGTACAGCAGACTGACCGTGGACA T A A C L T G S E S N I S 187 CYTX-115-PCT 4862-0152WO1 YGMHWVRQAPGKGLEWVAFIRYDGSNKYYADSVK GRFTISRDNSKNTLYLQMNSLRAEDTAVYYCKTHGS C V K A R E S K G G A T A A T C G T C C C A A 188 CYTX-115-PCT 4862-0152WO1 AAAGACCGCTCGGGAAAAACTTAAACATTATTCATG CACTGCAGAGGACATCGACCACGAAGACATCACCAG G G A T A T T T T G A T A A G A 189 CYTX-115-PCT 4862-0152WO1 GGTGTCCAACAAGGGCCTGCCTAGCAGCATCGAGAA AACAATCAGCAAGGCCAAGGGCCAGCCTCGCGAACC T A A C L T G S S L 190 CYTX-115-PCT 4862-0152WO1 EEPDFYKTKIKLCILLHAFRIRAVTIDRVMSYLNASGGSPW GLHQSRSGGGGSGGGGSGGSGSGGGGSGGGGSGGSQS A L S S A S V G G A T A A T C G T C C C A A t 191 CYTX-115-PCT 4862-0152WO1 ccggtcgctactcccgatccaggtatgtttccatgtttgcaccacagccagaacttgttga gggcagtatccaatatgctgcagaaagcacggcaaacactggaattctacccatgcact tg t tc c gt c c A G A A G a T c g t g a at c g 192 CYTX-115-PCT 4862-0152WO1 cagatggcagcagggcaacgtgttcagctgcagcgtgatgcacgaggccctGCA CAACCACTACACCCAGAAGtctctgagcctgagcTGA L T G S S L S K S A R S V Q G G A T A 193 CYTX-115-PCT 4862-0152WO1 AGATGCGAGGCCAAGAACTACAGCGGCCGGTTCACA TGTTGGTGGCTGACCACCATCAGCACCGACCTGACC T C G T C C C A A t a ct tg t tc c gt c c G G A G G T 194 CYTX-115-PCT 4862-0152WO1 CGACGGCTCCAACAAGTACTACGCCGACTCCGTGAA GGGCAGATTCACCATCTCCAGAGACAACTCCAAGAA A G T G g G g t C a t c a c g t ct L T G S E S N A L S A R 195 CYTX-115-PCT 4862-0152WO1 KTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVS NKGLPSSIEKTISKAKGQPREPQVYTLPPCQEEMTKNQ S T E S K L G G A T A A T C G T C C C A A G G 196 CYTX-115-PCT 4862-0152WO1 AGAGACCAGTTCAACTACCCGGGGAAGTTGCTTGCC GCCACAGAAGACCTCCCTCATGATGACCTTGTGTCTG A T A G G G C G T A T C G C T C G 197 CYTX-115-PCT 4862-0152WO1 GATGACCAAGAATCAGGTGTCCCTGTGGTGCCTGGT CAAGGGCTTCTACCCTTCCGATATCGCCGTGGAATG T G G T T A C g T A C T T G A L T G S E S N 198 CYTX-115-PCT 4862-0152WO1 QLPGTAPKLLIYYNDQRPSGVPDRFSGSKSGTSASLA ITGLQAEDEADYYCQSYDRYTHPALLFGTGTKVTVL S A S L S S T E S K L G G A T A A T C G T C C C A A 199 CYTX-115-PCT 4862-0152WO1 TGGGCCAGCGTGCCATGTTCTGGTGGCGGAGGATCT GGCGGAGGTGGAAGCGGCGGAGGCGGATCTAGAGT G G G A T A G G G C G T A T C G T C G 200 CYTX-115-PCT 4862-0152WO1 TGACCTGCGTGGTGGTCGACGTGTCACAAGAGGATC CCGAGGTGCAGTTCAATTGGTACGTGGACGGCGTGG a G C G T G G T T A C g T A C T T G A L T G 201 CYTX-115-PCT 4862-0152WO1 ASISVRAQDRYYSSSWSEWASVPCSGGGGSGGGGSGGGGS RVIPVSGPARCLSQSRNLLKTTDDMVKTAREKLKHYSCTAE S N L P R D G I K L K E S K L G G A T A A T C G 202 CYTX-115-PCT 4862-0152WO1 CAGCTTTTTCATCCGGGACATCATCAAGCCCGATCCT CCAAAGAACCTGCAGCTGAAGCCTCTGAAGAACAGC C C A A G G G A T A T G G C A G A C C A 203 CYTX-115-PCT 4862-0152WO1 TCTCCAGAGACAACTCCAAGAACACCCTGTACCTGC AGATGAACAGCCTGAGAGCCGAGGATACCGCCGTGT G A T A A tt C T G T T T G T T A C g T A C T T G A 204 CYTX-115-PCT 4862-0152WO1 1604 ProC5748 chain 1 IWELKKDVYVVELDWYPDAPGEMVVLTCDTPEEDGITWT L T G S E S N A S S T Y L E T E S G a a c c c a g t 205 CYTX-115-PCT 4862-0152WO1 aagctgaagtacgaaaactacacgtcaagcttctttatccgagacattataaaaccggac cctcccaaaaatctgcaactcaagcctcttaaaaacagtagacaggttgaagtaagctg g c a T C G T A C A G G T G C C A A T C T G C G 206 CYTX-115-PCT 4862-0152WO1 1607 ProC5748 chain 2 atgagagcctggatctttttcctgctgtgcctggcagggcgcgcactggctCAATC DNA sequence AGTTCTTACCCAACCGCCGAGCGTCTCAGGCGCTCC G G C G T G G T C A G G T L T 207 CYTX-115-PCT 4862-0152WO1 CWWLTTISTDLTFSVKSSRGSSDPQGVTCGAATLSAERVRG DNKEYEYSVECQEDSACPAAEESLPIEVMVDAVHKLKYEN S S S L S K S A R S S T Y G L E S S V D Q G G A T 208 CYTX-115-PCT 4862-0152WO1 TTGGCGACGCCGGCCAGTACACCTGTCACAAAGGCG GAGAAGTGCTGAGCCACAGCCTGCTGCTGCTCCACA A A T C G T C C C A A t a ct tg t tc c gt c c G G A G G 209 CYTX-115-PCT 4862-0152WO1 TTGAATCTGGCGGCGGAGTTGTGCAGCCTGGCAGAA GTCTGAGACTGAGCTGTGCCGCCAGCGGCTTCACCTT C A G T G T A G C T T A A G G G T G G T A 210 CYTX-115-PCT 4862-0152WO1 AGTGACCGCCGTGAATAGCCTGGGCAGCTCTAGCTC TCTGCCCTCCACCTTCACCTTTCTGGACATCGTCAGA A C T T G G C C C A C C T C C T L T G S S L 211 CYTX-115-PCT 4862-0152WO1 GSQSVLTQPPSVSGAPGQRVTISCSGSRSNIGSNTVK WYQQLPGTAPKLLIYYNDQRPSGVPDRFSGSKSGTS K S A R S S T Y G L E R S V D Q G G A T A A T C 212 CYTX-115-PCT 4862-0152WO1 CGCCGTGCACAAGCTGAAGTACGAGAACTACACCAG CAGCTTTTTCATCCGGGACATCATCAAGCCCGATCCT C C C A A t a ct tg t tc c gt c c G G A G G T A G T G T 213 CYTX-115-PCT 4862-0152WO1 cctccatgtcctgctccagagTTTGAAGGCGGCCCTTCCGTGTTC CTGTTTCCACCTAAGCCTAAGGACACCCTGATGATCA G C T T A A G G G T G G T A A C C T T 214 CYTX-115-PCT 4862-0152WO1 CCCATGGGGCCTGCTTGGAGGATCTGGACCTCCTTGT cctccatgtcctgctccagagTTTGAAGGCGGCCCTTCCGTGTTC A G A C C T C C T L T G S E S N A L S S A W T P 215 CYTX-115-PCT 4862-0152WO1 LVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFF LYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLS Y T G S L E P N G G A T A A T C G T C C C A A 216 CYTX-115-PCT 4862-0152WO1 TATCCCAGTAAGCGGGCCGGCACGGTGTCTCTCCCA ATCACGCAACCTCCTTAAAACAACAGACGATATGGT G G G G A T A G G G C G T C C C G T G 217 CYTX-115-PCT 4862-0152WO1 CCAAGACCAAGcctagagaggaacagttcaacAGCACCTACAG AGTGGTGTCCGTGCTGACCGTGCTGCACCAGGATTG A G A C G a T A G C T G C C G C A A G 218 CYTX-115-PCT 4862-0152WO1 GTGGTGGTGGACGTTTCCCAAGAGGACCCTGAGGTG CAGTTCAATTGGTACGTGGACGGCGTGGAAGTGCAC G A G T G L T G S E S N A L S S A W T P S 219 CYTX-115-PCT 4862-0152WO1 1621 ProC5808 chain 2 NIDVCKLGTVTVQPAPVIPLGSAANISCSLNPKQGCSHY amino acid PSSNELILLKFVNDVLVENLHGKKVHDHTGHSSTFQVT E G S L E P N G G A T A A T C G T C C C A A 220 CYTX-115-PCT 4862-0152WO1 CACTGCAGAGGACATCGACCACGAAGACATCACCAG AGATCAGACCTCAACTCTCAAAACATGTCTGCCATT G G A T A G G G C G T C C C G T G A 221 CYTX-115-PCT 4862-0152WO1 CAAGGGCCTGCCTAGCAGCATCGAGAAAACAATCAG CAAGGCCAAGGGCCAGCCTCGCGAACCTCAGGTTTA A C G a T A G C T G C C G C A G G C C 222 CYTX-115-PCT 4862-0152WO1 GCACCTACAGAGTGGTGTCCGTGCTGACCGTGCTGC ACCAGGATTGGCTGAACGGCAAAGAGTACAAGTGCA A C C C L T G S S L S K Q V N G Y G 223 CYTX-115-PCT 4862-0152WO1 YCDYLDFGINLTPESPESNFTAKVTAVNSLGSSSSLPST FTFLDIVRPLPPWDIRIKFQKASVSRSTLYWRDEGLVLL E S R F L G A C T C A C C A A C C G G T G 224 CYTX-115-PCT 4862-0152WO1 TTCATCACCAACGGCTCTTGCCTGGCCAGCAGAAAG ACCTCCTTCATGATGGCCCTGTGCCTGAGCAGCATCT A C A T G G T T G C C G G C T T C T A T A 225 CYTX-115-PCT 4862-0152WO1 CCCAGAGAACCCCAGGTGTACACACTGCCTCCATGC AGAGATGAGCTGACCAAGAACCAGGTGTCCCTGTGG G T G A A G C A C A A G C A G G C G G 226 CYTX-115-PCT 4862-0152WO1 TACAAGTGCAAGGTGTCCAACAAGGCCCTGCCTGCC AGCATCGAGAAAACCATCTCTAAGGCCAAGGGCCAG C T A L T G S S L S K Q V N G Y G 227 CYTX-115-PCT 4862-0152WO1 GPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKF NWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQ C G A C T C A C C A A C C G G T G T A C 228 CYTX-115-PCT 4862-0152WO1 ACGAGCTGATGCAGGCCCTGAACTTCAACAGCGAGA CAGTGCCCCAGAAGTCCAGCCTGGAAGAACCCGACT G G T T G C C G G C T T C T A T A G G T 229 CYTX-115-PCT 4862-0152WO1 CATTCTTCCTGTACAGCAAGCTGACAGTGGACAAGA GCAGATGGCAGCAGGGCAACGTGTTCAGCTGCAGCG A A G C A C A A A A G C C T G G 230 CYTX-115-PCT 4862-0152WO1 1632 ProC5854 chain 1 IWELKKDVYVVELDWYPDAPGEMVVLTCDTPEEDGITWT amino acid LDQSSEVLGSGKTLTIQVKEFGDAGQYTCHKGGEVLSHSL T G S S L S K Q V N G Y C N G A C T C A 231 CYTX-115-PCT 4862-0152WO1 CCGACATCCTGAAGGACCAGAAAGAGCCCAAGAAC AAGACCTTCCTGAGATGCGAGGCCAAGAACTACAGC A A C C G G T G T A C A T G G T T 232 CYTX-115-PCT 4862-0152WO1 GGACGAGGCCGACTACTACTGTCAGAGCTACGACCG GTACACACACCCCGCTCTGCTGTTTGGCACCGGCACC C G G C T T C T A T A G G T G A A G C 233 CYTX-115-PCT 4862-0152WO1 GGCGTTGGCGGCGGAGGATCTGGCGGAGGTGGAAGT GGTGGTAGCGGCAGCGATAGCACCCACACCTGTCCT G T A T A G C C L T G S E S N T A Q S T T 234 CYTX-115-PCT 4862-0152WO1 FYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSK LTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG tt a a a a g c ac t g ta t gt at g A G C T A C G A C C 235 CYTX-115-PCT 4862-0152WO1 AACAAGGCCCTGCCTGCCAGCATCGAGAAAACCATC AGCAAGGCCAAGGGCCAGCCTAGGGAACCCCAGGTT T c A C G A C C C C T A L T G S E S N 236 CYTX-115-PCT 4862-0152WO1 YRVKMKLCILLHAFSTRVVTINRVMGYLSSAGGSDHQSRS GPWGLLGGGGSGGGGSGGSGSGGGGSGGGGSGGSQS A L S S A W S L K T G G G A T A A T C G T C C C 237 CYTX-115-PCT 4862-0152WO1 GTGATCTGCAGAAAGAACGCCAGCATCAGCGTCAGA GCCCAGGACCGGTACTACAGCAGCTCTTGGAGCGAA G G G A T A G G G C G T C C C 238 CYTX-115-PCT 4862-0152WO1 GGCCCaTCCGTGTTCCTGTTTCCTCCAAAGCCTAAGG ACACCCTGATGATCAGCAGAACCCCTGAAGTGACCT G G T T T T C A T T T C L T G 239 CYTX-115-PCT 4862-0152WO1 YTSSFFIRDIIKPDPPKNLQLKPLKNSRQVEVSWEYPDTWS TPHSYFSLTFCVQVQGKSKREKKDRVFTDKTSATVICRKN S E S N A L S A R D N N H T G G G A T A A T C 240 CYTX-115-PCT 4862-0152WO1 CGCCGTGCACAAGCTGAAGTACGAGAACTACACCAG CAGCTTTTTCATCCGGGACATCATCAAGCCCGATCCT C C C A A G G G A T A G G G C G T 241 CYTX-115-PCT 4862-0152WO1 ACTACGCCGACTCCGTGAAGGGCAGATTCACCATCT CCAGAGACAACTCCAAGAACACCCTGTACCTGCAGA T C G a C G G C G T T g A T T T C 242 CYTX-115-PCT 4862-0152WO1 ACGAGGCCCTgcacaaccactacacccagaagTCCCTGTCTCTG AGCCCTGGAAAATGA L T G S E S N A L S A S D N N H T G T G C G 243 CYTX-115-PCT 4862-0152WO1 ACATCCTGAAGGACCAGAAAGAGCCCAAGAACAAG ACCTTCCTGAGATGCGAGGCCAAGAACTACAGCGGC C A A C C A A A A A A C T C 244 CYTX-115-PCT 4862-0152WO1 TGTCAGAGCTACGACCGGTACACACACCCCGCTCTG CTGTTTGGCACCGGCACCAAAGTGACAGTGCTTGGA T A G C G A C C C T T c A A T 245 CYTX-115-PCT 4862-0152WO1 GAGCTGACCAAGAATCAGGTGTCCCTGAGCTGTGCC GTGAAGGGCTTCTACCCTTCCGATATCGCCGTGGAAT T C L T G S S L S K Q V N G T G G 246 CYTX-115-PCT 4862-0152WO1 CTGGCGAGATGGTGGTGCTGACCTGCGATACCCCTG AAGAGGACGGCATCACCTGGACACTGGATCAGTCTA C T C A C A A C C G G T G T A C A T G G T 247 CYTX-115-PCT 4862-0152WO1 GTCTGGTGCCCCTGGACAGAGAGTGACCATCAGCTG TAGCGGCAGCAGAAGCAACATCGGCAGCAACACCGT A G C C G G C T T C T A T A G G T G A 248 CYTX-115-PCT 4862-0152WO1 CGTGGTGGTGGATGTGTCTCACGAGGACCCCGAAGT GAAGTTCAATTGGTACGTGGACGGCGTGGAAGTGCA T T T C L T G S S L S K S A R D N N H 249 CYTX-115-PCT 4862-0152WO1 1657 ProC5880 chain 2 DSTHTCPPCPAPEFEGGPSVFLFPPKPKDTLMISRTPEVT amino acid CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQY E G L T G S S L S K Q V N D P V E T G L T G 250 CYTX-115-PCT 4862-0152WO1 YTSSFFIRDIIKPDPPKNLQLKPLKNSRQVEVSWEYPDTWS TPHSYFSLTFCVQVQGKSKREKKDRVFTDKTSATVICRKN S S L S K Q V N G P V E T G L T G D A V K 251 CYTX-115-PCT 4862-0152WO1 GQPREPQVYTLPPCQEEMTKNQVSLWCLVKGFYPSDIA VEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSR E S K L T G V R A I S S L S R F L TT C A C C G 252 CYTX-115-PCT 4862-0152WO1 ATTTACGTGCTGGTGGTTGACTACGATATCTACCGATTTGACCTTTTCAG TGAAGTCAAGCAGAGGTTCTTCCGACCCCCAGGGAGTGACATGTGGT T G A A C G T C G C C A T T T A G T T A A G A G T C C T T T A A T A G A T C C G A T 253 CYTX-115-PCT 4862-0152WO1 AGTCTCAGTCTTGACGGTCCTTCACCAAGACTGGTTGAATGGAAAGGA GTATAAGTGTAAAGTGAGCAACAAGGGTCTTCCCTCAAGCATAGAAAAA CT G T T A A C A C T C C A C g g g a a t g gg a a a a c ct g G G 254 CYTX-115-PCT 4862-0152WO1 GACACTCTCATGATTTCAAGGACCCCAGAGGTAACCTGCGTCGTCGTG GATGTTAGTCAGGAAGATCCCGAAGTTCAGTTCAATTGGTACGTTGACG C T G A T C A T C T T T C A T C G C T A G at c ga g a gg g tc at T G C A A G 255 CYTX-115-PCT 4862-0152WO1 CGAGGAACAATTCAATTCTACTTATAGGGTCGTCTCCGTCTTGACAGTG TTGCATCAAGATTGGCTGAATGGCAAAGAATATAAGTGTAAAGTTTCCAA G T A T A g g g a a t g gg a a a a c ct g c c ag t c t g ca a c C A A A G A 256 CYTX-115-PCT 4862-0152WO1 GGGTTTTTACCCCTCCGATATAGCCGTGGAATGGGAGTCTAACGGTCA GCCTGAGAATAACTATAAGACCACCCCGCCGGTCCTTGATTCCGATGG G T T T T C A T C G C T A G G C C C C C A T G T G T A T T G A tc 257 CYTX-115-PCT 4862-0152WO1 cggacgcaccaggtgagatggtagtacttacatgtgatacgccagaagaggacgggattaca tggactctcgaccagagttccgaggtacttggctctggaaaaactctcacgatccaggttaag c ag g c a cc t a a g g g ca a c a c c gt g ga G G T A G G A A T A C T T A C A C 258 CYTX-115-PCT 4862-0152WO1 GTCTCCGTCTTGACAGTGTTGCATCAAGATTGGCTGAATGGCAAAGAAT ATAAGTGTAAAGTTTCCAATAAGGGACTGCCGAGTTCCATTGAGAAGAC C A C A A t g a a a c t t g a g c a a g t a a a t g t tg g T C C T A C G A 259 CYTX-115-PCT 4862-0152WO1 GCATAGAAAAAACCATTTCTAAGGCTAAAGGTCAACCCCGAGAGCCAC AGGTCTACACTCTTCCACCATGCCAAGAGGAAATGACAAAGAATCAGG T C T G A C A C T C C A C A G G a a a tt gg c a a c g a t ga c g c 260 CYTX-115-PCT 4862-0152WO1 acagccagaacttgttgagggcagtatccaatatgctgcagaaagcacggcaaacactgga attctacccatgcacttcagaagagatagaccatgaggatattactaaagacaaaacctcta g c a ag c g G G A G A G G A A T A C T T A C A C T C C A C A 261 CYTX-115-PCT 4862-0152WO1 GCGGCAGCGGTGGGTCAatctgggagttgaaaaaagatgtgtatgtagttgagctgg attggtatccggacgcaccaggtgagatggtagtacttacatgtgatacgccagaagaggacg c c c t a gt g a g c a a g t a a a t g t tg g T C C T A C G A C G T C T G a c tg c a 262 CYTX-115-PCT 4862-0152WO1 aaactctcacgatccaggttaaggaatttggagatgctggtcagtacacctgtcacaaaggag gagaagtgttgagtcactctttgcttcttctccacaagaaggaggacgggatctggagtaccga at a g a g a a a a t c g a a ga gt a a c a g g tt a gt gt t c tt ct g A C A C T C C A 263 CYTX-115-PCT 4862-0152WO1 CCCGATGGCAAGAAGGCAATGTCTTCTCTTGCAGCGTGATGCACGAA GCACTGCACAACcgcttcACGCAGAAAAGCCTGTCCCTGAGCCTGGGC A A G gt tt tt tt g g g c t a a c g g g c g t a tg a g c a G T A T A A C C T G T G 264 CYTX-115-PCT 4862-0152WO1 AAGCACTTCATAATCATTACACACAAAAGAGCCTGTCCCTGAGCCTGG GCTGA A C A C T C C A C A C g a g tc a gt c a g a tt tc c c g a g c g tt a c 265 CYTX-115-PCT 4862-0152WO1 gagttgatgcaagcactgaatttcaattctgagaccgtgcctcaaaaatctagtctggaggaa cccgatttttacaaaacgaagatcaagctctgtattttgcttcatgcgtttaggattagggccgta G T G A G A G A A T C A C A C T C C A C A tc a g c ag g 266 CYTX-115-PCT 4862-0152WO1 gtggttgacgactatcagtacggacctcaccttctccgttaagtcttcccggggatcttccgac cctcaaggggtaacttgcggggcggcgactctgagtgccgagcgcgtgaggggtgataacaa cc t a a g g T T G TT C G A A T T T G A gt a at c tt a t t t a C C A A C C 267 CYTX-115-PCT 4862-0152WO1 GGGCAGCCAGAAAACAATTACAAAACGACACCACCCGTACTTGATTCC GATGGATCTTTTTTCCTCGTTAGTCGGCTCACTGTGGACAAGTCCCGAT G G A A t g a a a c t t g a g c a a g C T A G G T C T G A T gt a at c tt 268 CYTX-115-PCT 4862-0152WO1 ggcgtcccgcaagacctcctttatgatggctctttgcctttcctccatatatgaggaccttaaaa tgtaccaggtggagttcaagacaatgaacgcgaaactcctgatggatccaaagaggcaaat t t a C C A A C C C T G A G G a a a tt gg c a a c g a t ga c AT T G TT C 269 CYTX-115-PCT 4862-0152WO1 GGTCCTTCACCAAGACTGGTTGAATGGAAAGGAGTATAAGTGTAAAGTG AGCAACAAGGGTCTTCCCTCAAGCATAGAAAAAACCATTTCTAAGGCTA A T T T G A gt a at c tt a t t t a C C A A C C C T G A g cg c c c 270 CYTX-115-PCT 4862-0152WO1 aaaaggagccaaagaataaaacgttccttagatgcgaggcgaagaattatagcggccggtt cacgtgctggtggttgacgactatcagtacggacctcaccttctccgttaagtcttcccgggga gt g a g c a a g C T A G G T C T G A T gt a at c tt a t t t a C C A A C 271 CYTX-115-PCT 4862-0152WO1 GTCAAAGGGTTCTACCCGAGTGATATCGCAGTTGAATGGGAGAGTAAC GGGCAGCCAGAAAACAATTACAAAACGACACCACCCGTACTTGATTCC T G A A G gt tt tt tt g g g c t a a c g g C A A A G A A G gt a at c 272 CYTX-115-PCT 4862-0152WO1 ttaccaagaacgaaagctgtttgaacagccgcgagacaagctttatcacgaatggttcctgttt ggcgtcccgcaagacctcctttatgatggctctttgcctttcctccatatatgaggaccttaaaa t t t a C C A A C C C T G A C g a g tc a gt c a g a tt tc c c C C A A 273 CYTX-115-PCT 4862-0152WO1 ACCCCGAGAGGAACAGTTCAACTCTACATACAGAGTAGTCTCAGTCTT GACGGTCCTTCACCAAGACTGGTTGAATGGAAAGGAGTATAAGTGTAAA G G A A G gt a at c tt a t t t a C C A A C C C T G A G a a a tt 274 CYTX-115-PCT 4862-0152WO1 gcttcttctccacaagaaggaggacgggatctggagtaccgacatactgaaggatcaaaagg agccaaagaataaaacgttccttagatgcgaggcgaagaattatagcggccggttcacgtgc a a c g a t ga c AT T G TT C G A A T T T G A gt a at c tt a t t t a C C A A C 275 CYTX-115-PCT 4862-0152WO1 CCATCTCAGGAAGAAATGACTAAAAACCAGGTGTCTCTGTCTTGCGCA GTCAAAGGGTTCTACCCGAGTGATATCGCAGTTGAATGGGAGAGTAAC C T G A C G a a a tt gg c a a c g a t ga c AT T G TT C G A A T T T G A gt a at 276 CYTX-115-PCT 4862-0152WO1 agaccatgaggatattactaaagacaaaacctctacagtcgaggcatgcctccctcttgaac ttaccaagaacgaaagctgtttgaacagccgcgagacaagctttatcacgaatggttcctgttt a t t t a C C A A C C C T G A G a a a tt gg c a a c g a t ga c AT T G TT 277 CYTX-115-PCT 4862-0152WO1 CAATTGGTACGTTGACGGAGTAGAGGTACACAATGCCAAAACCAAACC CCGAGAGGAACAGTTCAACTCTACATACAGAGTAGTCTCAGTCTTGAC G A A T T T G A gt a at c tt a t t t a C C A A C C C T G A C G a a a 278 CYTX-115-PCT 4862-0152WO1 aggaatttggagatgctggtcagtacacctgtcacaaaggaggagaagtgttgagtcactcttt gcttcttctccacaagaaggaggacgggatctggagtaccgacatactgaaggatcaaaagg c a a c g a t ga c AT T G TT C G A A T T T G A gt a at c tt a t t t a C C A A C 279 CYTX-115-PCT 4862-0152WO1 TAAAGCCAAAGGCCAGCCTCGAGAACCCCAAGTATGCACGCTCCCC CCATCTCAGGAAGAAATGACTAAAAACCAGGTGTCTCTGTCTTGCGCA C C T G A G a a a tt gg c a a c g a t ga c AT T G TT C G A A T T T G A gt a 280 CYTX-115-PCT 4862-0152WO1 tccaatatgctgcagaaagcacggcaaacactggaattctacccatgcacttcagaagagat agaccatgaggatattactaaagacaaaacctctacagtcgaggcatgcctccctcttgaac ttt a t t t a C C A A C C C T G A T c t g tt c gt c g g c a t tt c A T 281 CYTX-115-PCT 4862-0152WO1 AACCTGCGTCGTCGTGGATGTTAGTCAGGAAGATCCCGAAGTTCAGTT CAATTGGTACGTTGACGGAGTAGAGGTACACAATGCCAAAACCAAACC C G A A T T T G A gt a at c tt a t t t a C C A A C C C T G A gt tt 282 CYTX-115-PCT 4862-0152WO1 acatggactctcgaccagagttccgaggtacttggctctggaaaaactctcacgatccaggtt aaggaatttggagatgctggtcagtacacctgtcacaaaggaggagaagtgttgagtcactctt g g g c t a a c g g C A A A G A A G gt a at c tt a t t t a C C A A 283 CYTX-115-PCT 4862-0152WO1 GTAAAGTTTCCAATAAGGGACTGCCGAGTTCCATTGAGAAGACTATCTC TAAAGCCAAAGGCCAGCCTCGAGAACCCCAAGTATGCACGCTCCCC A C C T G A A a a a tt gg c a a c g a t ga c AT T G TT C G A A T T T G A 284 CYTX-115-PCT 4862-0152WO1 1712 ProC2702 DNA2 atgagagcctggatctttttcctgctgtgcctggcagggcgcgcactggctaggaatcttccggt cgctactcccgatccaggtatgtttccatgtttgcaccacagccagaacttgttgagggcagta at c tt a t t t a C C A A C C C T G A C gt tt tt tt g g g c t a a c g g C 285 CYTX-115-PCT 4862-0152WO1 CCCCATGTCCAGCCCCAGAATTCGAGGGTGGCCCCAGCGTCTTCCT CTTTCCTCCGAAACCCAAGGACACTCTCATGATTTCAAGGACCCCAGA A A G A A G gt a at c tt a t t t a C C A A C C C T G A C 286 CYTX-115-PCT 4862-0152WO1 GCAGCGGTGGGTCAatctgggagttgaaaaaagatgtgtatgtagttgagctggattggt atccggacgcaccaggtgagatggtagtacttacatgtgatacgccagaagaggacgggatt tt tt g g g c t a a c g g C A A A G A A G gt a at c tt a t t t a C C A A 287 CYTX-115-PCT 4862-0152WO1 ACAAAACCACGCGAGGAACAATTCAATTCTACTTATAGGGTCGTCTCC GTCTTGACAGTGTTGCATCAAGATTGGCTGAATGGCAAAGAATATAAGT C C C T G A G a a a tt gg c a a c g a t ga c AT T G TT C G A A T T T G A 288 CYTX-115-PCT 4862-0152WO1 1718 PRoC2705 DNA atgagagcctggatctttttcctgctgtgcctggcagggcgcgcactggctaggaatcttccggt a at c tt a t t t a C C A A C C C T G G G G T C A C A C A T G a 289 CYTX-115-PCT 4862-0152WO1 gatgtgtatgtagttgagctggattggtatccggacgcaccaggtgagatggtagtacttacatg tgatacgccagaagaggacgggattacatggactctcgaccagagttccgaggtacttggct a a c tc g a a c t a g g T G T G A A T G G G C gt a at c tt a t t t a C C A A 290 CYTX-115-PCT 4862-0152WO1 ACAAAACCACGCGAGGAACAATTCAATTCTACTTATAGGGTCGTCTCC GTCTTGACAGTGTTGCATCAAGATTGGCTGAATGGCAAAGAATATAAGT C C C T G G C G A C A T C T T A A C T G C C T T G G A A G C C 291 CYTX-115-PCT 4862-0152WO1 CTGAATGCCAGCGGCGGCAGCGATCACCAGTCTAGATCTGGACCTTG GGGACTGCTTGGAGGCGGAGGAAGTGGTGGCGGCGGAAGTGGCGG CT C C A G C T C T G A T A T C C G C C C C T T A C A A G 292 CYTX-115-PCT 4862-0152WO1 GTGCCGTGAAGGGCTTCTACCCTTCCGATATCGCCGTGGAATGGGAG AGCAATGGCCAGCCTGAGAACAACTACAAGACCACACCTCCTGTGCT A C A G C G A C A T C T T A A C T G C C T T G G A A G C C G T C 293 CYTX-115-PCT 4862-0152WO1 CAACACCGTGAAGTGGTATCAGCAACTGCCCGGCACAGCCCCTAAAC TGCTGATCTACTACAACGACCAGCGGCCTAGCGGCGTGCCCGATAGA G C T A A G C A C C C G C T G G G C C G T C C T T A C A A G G T A C 294 CYTX-115-PCT 4862-0152WO1 GAGGCCCTgcacaaccactacacccagaagTCCCTGTCTCTGAGCCCTGGA AAATGA G C G A C A T C T T A A C T G C C T T G G A A G C C G T C C A G 295 CYTX-115-PCT 4862-0152WO1 ACTGCAGGCCGAGGACGAGGCCGACTACTACTGTCAGAGCTACGAC CGGTACACACACCCCGCTCTGCTGTTTGGCACCGGCACCAAAGTGAC AT A A G C A G G C G G A T T C A C C C C T T A C A A G G T A C A 296 CYTX-115-PCT 4862-0152WO1 1727 ProC670 chain 1 atgagagcctggatctttttcctgctgtgcCTGGCTGGGCGCGCACTGGCTatctgg DNA sequence gagttgaaaaaagatgtgtatgtagttgagctggattggtatccggacgcaccaggtgagatgg cg a a t g gg a a a a c ct g c c ag t c t g ca a c C A A A G A A G T A C A C 297 CYTX-115-PCT 4862-0152WO1 GCCAAAACAAAACCACGCGAGGAACAATTCAATTCTACTTATAGGGTC GTCTCCGTCTTGACAGTGTTGCATCAAGATTGGCTGAATGGCAAAGAAT C C A C [00304] In any of the foregoing sequences having a C-terminal lysine (K) residue, the present disclosure includes polypeptides wherein the C-terminal lysine is absent, e.g., proteins in which the C-terminal lysine (K) has been cleaved during secretion from mammalian cells. NUMBERED ASPECTS [00305] The following numbered aspects also form part of the instant disclosure. [00306] Aspect 1. An activatable interleukin 12 (IL12) fusion protein comprising afirst polypeptide having a structure selected from: i) N'-DD-L1-MM-L2-IL12-C', ii) C'-DD-L1-MM-L2-IL12-N', iii) N'-DD-L1-IL12-L2-MM-C', or iv) C'-DD-L1-IL12-L2-MM-N', wherein: a) L1 is afirst linker or is absent; b) L2 is a second linker; c) DD is a dimerization domain; d) MM is a masking moiety; e) IL12 comprises an IL12α (p35) domain and an IL12β (p40) domain; f) N' is an amino terminus of the activatable IL12 fusion protein; and g) C' is a carboxy terminus of the activatable IL12 fusion protein, 298 CYTX-115-PCT 4862-0152WO1 wherein at least one of L1 and L2 comprises a cleavable moiety (CM). [00307] Aspect 2. The activatable IL12 fusion protein of aspect 1, wherein the activatable IL12 fusion protein has 1.5-fold to about 1000-fold, or about 2-fold to about 100-fold, or about 100-fold to about 1000-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. [00308] Aspect 3. The activatable IL12 fusion protein of aspect 1 or 2, wherein the fusion protein comprises a second polypeptide comprising a second dimerization domain (DD2), and wherein the DD and the DD2 are dimerized. [00309] Aspect 4. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the dimer is not a homodimer. [00310] Aspect 5. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the L2 comprises a CM, and the L1 is absent or the L1 does not comprise a CM. [00311] Aspect. A. The activatable IL12 fusion protein of any of the aspects disclosed herein, wherein L1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. [00312] Aspect. B. The activatable IL12 fusion protein of any of the aspects disclosed herein, wherein L2 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids. [00313] Aspect C. The activatable IL12 fusion protein of any one of aspects 3 to 4, having a structure comprising: i) C'-DD1-L1-MM-CM-IL12-N', and DD2; or ii) N'-DD1-L1-MM-CM-IL12-C', and DD2. [00314] Aspect D. The activatable IL12 fusion protein of any one of aspects 3 to 4, wherein the CM is a first cleavable moiety (CM1) and further comprising a second cleavable moiety (CM2). [00315] Aspect E. The activatable IL12 fusion protein of aspect D, having a structure comprising: 299 CYTX-115-PCT 4862-0152WO1 i) C'-DD1-CM1-IL12-CM2-MM-N', and DD2; ii) N'-DD1-CM1-IL12-CM2-MM-C', and DD2; iii) C'-DD1-CM1-MM-CM2-IL12-N', and DD2; or vi) N'-DD1-CM1-MM-CM2-IL12-C', and DD2. [00316] Aspect F. The activatable IL12 fusion protein of aspect D, further comprising a third cleavable moiety (CM3). [00317] Aspect G. The activatable IL12 fusion protein of aspect F, having a structure comprising: i) C'-DD1-CM1-MM-CM2-IL12-N', and DD2; or ii) N'-DD1-CM1-MM-CM2-IL12-C', and DD2, wherein the MM comprises a first sequence (MM’) and a second sequence (MM”), and wherein the MM further comprises the CM3 within the MM sequence according to the structure comprising: MM’-CM3-MM”. [00318] Aspect H. The activatable IL12 fusion protein of aspect 3 or aspect 4, comprising afirst polypeptide having a structure N'-DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2- IL12-N', and a second polypeptide having a N'-DD2-L3-MM2-L4-IL12-C' or C'-DD2-L3-MM2- L4-IL12-N', wherein MM1 is a first masking moiety, MM2 is a second masking moiety, L3 is a third linker, and L4 is a fourth linker. [00319] Aspect I. The activatable IL12 fusion protein of aspect H, wherein L1 and L3 comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. [00320] Aspect J. The activatable IL12 fusion protein of aspect H or aspect I, wherein L2 and L4 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 300 CYTX-115-PCT 4862-0152WO1 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids. [00321] Aspect K. The activatable IL12 fusion protein of aspect H, wherein the CM is a first cleavable moiety (CM1) and further comprising a second cleavable moiety (CM2), a third cleavable moiety (CM3), and a fourth cleavable moiety (CM4), and having a structure comprising: i) C'-DD1-CM1-MM1-CM2-IL12-N', and C'-DD2-CM3-MM2-CM4-IL12-N'; or ii) N'-DD1-CM1-MM1-CM2-IL12-C', and N'-DD2-CM3-MM2-CM4-IL12-C'. [00322] Aspect L. activatable IL12 fusion protein of aspect 3 or aspect 4, comprising a first polypeptide having a structure N'-DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2-IL12- N'; and a second polypeptide having a structure N'-DD2-L3-MM2-C' or C'-DD2-L3-MM2-N', wherein MM1 is a first masking moiety, MM2 is a second masking moiety, and L3 is a third linker, wherein the MM1 comprises a first sequence (MM1’) and a second sequence (MM1”), and wherein the MM1 further comprises a second cleavable moiety (CM2) within the MM1 according to the structure comprising: MM1’-CM2-MM1”. [00323] Aspect M. The activatable IL12 fusion protein of aspect L, wherein L1 and L3 comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. [00324] Aspect N. The activatable IL12 fusion protein of aspect L or aspect M, wherein L2 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids. [00325] Aspect O. The activatable IL12 fusion protein of aspect 3 or aspect 4, wherein the CM is a first cleavable moiety (CM1) and further comprising a second cleavable moiety (CM2), a third cleavable moiety (CM3), and a fourth cleavable moiety (CM4), and having a structure comprising: i) C'-DD1-CM1-MM1-CM2-IL12-N', and C’DD2-CM3-MM2-N’; or 301 CYTX-115-PCT 4862-0152WO1 ii) N'-DD1-CM1-MM1-CM2-IL12-C', and N’-DD2-CM3-MM2-N’ wherein the MM1 comprises a first sequence (MM1’) and a second sequence (MM1”), and wherein the MM1 further comprises the CM4 within the MM1 according to the structure comprising: MM1’-CM4-MM1”. [00326] Aspect 6. The activatable IL12 fusion protein of any one of the preceding aspects, wherein at least one of the L1 and the L2 comprises a CM that is a substrate for a matrix metalloprotease (MMP) or a serine protease, or both. [00327] Aspect 7. The activatable IL12 fusion protein of aspect 6, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14. [00328] Aspect 8. The activatable IL12 fusion protein of any one of aspects 3 to 7, wherein the DD or the DD2 is an IgG Fc domain, optionally wherein the IgG Fc domain is a human IgG Fc domain. [00329] Aspect 9. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the MM is a Fab fragment or the MM is an scFv. [00330] Aspect 10. The activatable IL12 fusion protein of any one of aspects 3 to 9, wherein the DD and the DD2 are covalently bound to each other via at least one disulfide bond thereby forming a dimer. [00331] Aspect 11. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the IL12 comprises a linker between the p35 domain and the p40 domain. [00332] Aspect 12. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the DD is more proximal to the p35 domain than to the p40 domain. [00333] Aspect 13. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the DD is at the amino terminal end of thefirst polypeptide, and IL12 is at the carboxy terminal end of thefirst polypeptide. [00334] Aspect 14. The activatable IL12 fusion protein of any one of aspects 1 to 12, wherein the DD is at the carboxy terminal end of thefirst polypeptide, and IL12 is at the amino terminal end of thefirst polypeptide. [00335] Aspect 15. The activatable IL12 fusion protein of any one of aspects 1 to 12, wherein the L2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 58 to 98, 101 to 282, 318-1354, and 1388-1423 including any combination thereof. 302 CYTX-115-PCT 4862-0152WO1 [00336] Aspect 16. The activatable IL12 fusion protein of aspect 15, wherein the L1 is absent or comprises an amino acid sequence independently selected from the group consisting of SEQ ID NOs: 58 to 98, 101 to 282, 318-1354, and 1388-1423 including any combination thereof. [00337] Aspect 17. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the MM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 283 to 287, and 290 to 306, 1355 to 1362, 1426-1433, or a combination thereof, e.g., in some aspects, the MM comprises CDRs comprising SEQ ID NOs: 1355-1360, or in some aspects, the MM comprises SEQ ID NOs: 1361, 1362, or both, and in some aspects, SEQ ID NOs: 1361 and 1362 are connected by a linker. [00338] Aspect 18. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the MM is less than 300 amino acids in length. [00339] Aspect 19. The activatable IL12 fusion protein of any one of aspects 1 to 17, wherein the MM is about 400 to about 900 amino acids in length. [00340] Aspect 20. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the MM is an scFv comprising an amino acid sequence according to SEQ ID NO: 289. [00341] Aspect 21. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the MM is an scFv comprising a VL domain and a VH domain, and wherein the VL domain is proximal to the DD and VH is more proximal to the L2. [00342] Aspect 22. The activatable IL12 fusion protein of any one of aspects 1 to 20, wherein the MM is an scFv comprising a VL domain and a VH domain, and wherein the VL domain is more proximal to the L2 and VH is more proximal to the DD. [00343] Aspect 23. The activatable IL12 fusion protein of any one of the preceding aspects, wherein the activatable IL12 fusion protein has about 100-fold to about 500-fold less IL12 activity than a cleavage product of the activatable IL12 fusion protein in an IL12 reporter assay. [00344] Aspect 24. The activatable IL12 fusion protein of aspect 23, wherein the activatable IL12 fusion protein has about 200-fold to about 500-fold less IL12 activity than a cleavage product of the activatable IL12 fusion protein in an IL12 reporter assay. [00345] Aspect 25. The activatable IL12 fusion protein of any one of aspects 1 to 20, wherein the first polypeptide comprises SEQ ID NO: 1 and the second polypeptide comprises SEQ ID NO: 2. [00346] Aspect 26. The activatable IL12 fusion protein of any one of aspects 1 to 20, wherein h) thefirst polypeptide comprises SEQ ID NO: 7 and the second polypeptide comprises SEQ ID NO: 303 CYTX-115-PCT 4862-0152WO1 8; i) thefirst polypeptide comprises SEQ ID NO: 9 and the second polypeptide comprises SEQ ID NO: 10; j) thefirst polypeptide comprises SEQ ID NO: 11 and the second polypeptide comprises SEQ ID NO: 12; k) thefirst polypeptide comprises SEQ ID NO: 13 and the second polypeptide comprises SEQ ID NO: 14; l) thefirst polypeptide comprises SEQ ID NO: 15 and the second polypeptide comprises SEQ ID NO: 16; or m) thefirst polypeptide comprises SEQ ID NO: 17 and the second polypeptide comprises SEQ ID NO: 18. [00347] Aspect 27. An activatable IL12 construct comprising: afirst polypeptide having a structure N'-DD1-L1-p40-C' or C'-DD1-L1-p40-N', and a second polypeptide having a structure N'-DD2-L2-p35-L3-MM-C' or C'-DD2-L2-p35-L3-MM- N'; or ii) afirst polypeptide having a structure N'-DD1-L1-p35-C' or C'-DD1-L1-p35-N' and a second polypeptide having a structure N'-DD2-L2-p40-L3-MM-C' or C'-DD2-L2-p40- L3-MM-N', wherein: a) each of L1, L2, and L3 independently comprises a cleavable moiety (CM); b) DD1 is afirst dimerization domain and DD2 is a second dimerization domain, wherein DD1 and DD2 are dimerized; c) MM is a masking moiety; d) N' is an amino terminus; e) C' is a carboxy terminus; and wherein the activatable IL12 construct has about 50-fold to about 1000-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. [00348] Aspect 28. The activatable IL12 construct of aspect 27, wherein the CM is a substrate for an MMP or a serine protease, or both. [00349] Aspect 29. The activatable IL12 construct of aspect 27 or aspect 28, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14. [00350] Aspect 30. The activatable IL12 construct of any one of aspects 27 to 29, wherein the DD1 is at the amino terminal end of each of thefirst polypeptide and the second polypeptide. [00351] Aspect 31. The activatable IL12 construct of any one of aspects 27 to 29, wherein the DD1 is at the carboxy terminal end of each of thefirst polypeptide and the second polypeptide. [00352] Aspect 32. The activatable IL12 construct of any one of aspects 27 to 31, wherein each of the L1, the L2, and the L3 independently comprises an amino acid sequence selected from the 304 CYTX-115-PCT 4862-0152WO1 group consisting of SEQ ID NOs: 58 to 98, 101 to 282, 318-1354, and 1388-1423, including any combination thereof. [00353] Aspect 33. The activatable IL12 construct of any one of aspects 27 to 32, wherein the MM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 283 to 287, and 290 to 306, 1355-1362, 1426-1433, or a combination thereof, e.g., in some aspects, the MM comprises CDRs comprising SEQ ID NOs: 1355-1360, or in some aspects, the MM comprises SEQ ID NOs: 1361, 1362, or both, and in some aspects, SEQ ID NOs: 1361 and 1362 are connected by a linker. [00354] Aspect 34. The activatable IL12 fusion protein of any one of aspects 27 to 33, wherein the MM is less than 300 amino acids in length. [00355] Aspect 35. The activatable IL12 construct of any one of aspects 27 to 33, wherein the MM is about 400 to about 900 amino acids in length. [00356] Aspect 36. The activatable IL12 construct of any one of aspects 27 to 32, 34, and 35, wherein the MM is an scFv comprising an amino acid sequence according to SEQ ID NO: 289. [00357] Aspect 37. The activatable IL12 construct of any one of aspects 27 to 36, wherein the scFv comprises a VL domain and a VH domain, and wherein the VL domain is more proximal to the L3 than to a terminus of the activatable IL12 construct. [00358] Aspect 38. The activatable IL12 construct of any one of aspects 27 to 36, wherein the scFv comprises a VL domain and a VH domain, and wherein the VH domain is more proximal to the L3 than to a terminus of the activatable IL12 construct. [00359] Aspect 39. The activatable IL12 construct of any one of aspects 28 to 38, has about 50- fold to about 150-fold less IL12 activity than a cleavage product of the activatable IL12 construct in an IL12 reporter assay. [00360] Aspect 40. The activatable IL12 construct of any one of aspects 27 to 31, wherein h) the first polypeptide comprises SEQ ID NO: 3 and the second polypeptide comprises SEQ ID NO: 4; i) thefirst polypeptide comprises SEQ ID NO: 19 and the second polypeptide comprises SEQ ID NO: 20; j) thefirst polypeptide comprises SEQ ID NO: 21 and the second polypeptide comprises SEQ ID NO: 22; k) thefirst polypeptide comprises SEQ ID NO: 23 and the second polypeptide comprises SEQ ID NO: 24; l) thefirst polypeptide comprises SEQ ID NO: 25 and the second polypeptide comprises SEQ ID NO: 26; m) thefirst polypeptide comprises SEQ ID NO: 27 and the second polypeptide comprises SEQ ID NO: 28; n) thefirst polypeptide comprises SEQ ID NO: 305 CYTX-115-PCT 4862-0152WO1 29 and the second polypeptide comprises SEQ ID NO: 30; o) thefirst polypeptide comprises SEQ ID NO: 31 and the second polypeptide comprises SEQ ID NO: 32; p) thefirst polypeptide comprises SEQ ID NO: 33 and the second polypeptide comprises SEQ ID NO: 34; q) thefirst polypeptide comprises SEQ ID NO: 35 and the second polypeptide comprises SEQ ID NO: 36; r) thefirst polypeptide comprises SEQ ID NO: 37 and the second polypeptide comprises SEQ ID NO: 38; s) thefirst polypeptide comprises SEQ ID NO: 39 and the second polypeptide comprises SEQ ID NO: 40; t) thefirst polypeptide comprises SEQ ID NO: 41 and the second polypeptide comprises SEQ ID NO: 42; u) thefirst polypeptide comprises SEQ ID NO: 43 and the second polypeptide comprises SEQ ID NO: 44; v) thefirst polypeptide comprises SEQ ID NO: 45 and the second polypeptide comprises SEQ ID NO: 46; w) thefirst polypeptide comprises SEQ ID NO: 47 and the second polypeptide comprises SEQ ID NO: 48; x) thefirst polypeptide comprises SEQ ID NO: 49 and the second polypeptide comprises SEQ ID NO: 50; or y) thefirst polypeptide comprises SEQ ID NO: 51 and the second polypeptide comprises SEQ ID NO: 52. [00361] Aspect 41. An activatable IL12 construct comprising afirst polypeptide having a structure N'-DD1-L1-IL12-C' or C'-DD1-L1-IL12-N'; and a second polypeptide having a structure N'-DD2- L2-MM-C' or C'-DD2-L2-MM-N', wherein: (a) IL12 comprises a p35 domain and a p40 domain; (b) each of L1 and L2 independently is a cleavable moiety (CM); (c) DD1 is afirst dimerization domain and DD2 is a second dimerization domain, wherein DD1 and DD2 are dimerized; (d) MM is a masking moiety; (e) N' is an amino terminus; (f) C' is an carboxy terminus; and (g) the DD1 is more proximal to the p35 domain than to the p40 domain; and wherein the activatable IL12 construct has about 10-fold to about 50-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. In any of the aspects disclosed herein, L1 may comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. In any of the aspects disclosed herein, L21 may comprise about 20 amino acids to about 60 amino acids, about 22 amino acids to about 58 amino acids, or about 24 amino acids to about 56 amino acids. 306 CYTX-115-PCT 4862-0152WO1 [00362] Aspect 42. The activatable IL12 construct of aspect 41, wherein the CM is a substrate for an MMP or a serine protease, or both. [00363] Aspect 43. The activatable IL12 construct of aspect 42, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14. [00364] Aspect 44. The activatable IL12 construct of any one of aspects 41 to 43, wherein the IL12 comprises a linker between the p35 domain and the p40 domain. [00365] Aspect 45. The activatable IL12 construct of any one of aspects 41 to 44, wherein the DD1 is at the carboxy terminal end of thefirst polypeptide and the DD2 is at the carboxy terminal end of the second polypeptide. [00366] Aspect 46. The activatable IL12 construct of any one of aspects 41 to 45, wherein each of the L1 and the L2 independently comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 58 to 98, 101 to 282, 318-1354, and 1388-1423, including any combination thereof. [00367] Aspect 47. The activatable IL12 fusion protein of any one of aspects 41 to 46, wherein the MM is less than 300 amino acids in length. [00368] Aspect 48. The activatable IL12 construct of any one of aspects 41 to 46, wherein the MM is about 400 to about 900 amino acids in length. [00369] Aspect 49. The activatable IL12 construct of any one of aspects 41 to 48, wherein the MM is an scFv comprising an amino acid sequence according to SEQ ID NO: 289. [00370] Aspect 50. The activatable IL12 construct of any one of aspects 41 to 49, has about 100- fold to about 5-fold to 20-fold less IL12 activity than a cleavage product of the activatable IL12 construct in an IL12 reporter assay. [00371] Aspect 51. The activatable IL12 construct of any one of aspects 41 to 50, wherein thefirst polypeptide comprises SEQ ID NO: 5 and the second polypeptide comprises SEQ ID NO: 6. [00372] Aspect 52. A composition comprising the activatable IL12 fusion protein or the activatable IL12 construct of any one of the aspects disclosed herein, and a pharmaceutically acceptable carrier, or a container, vial, syringe, injector pen, or a kit comprising the activatable IL12 fusion protein or the activatable IL12 construct of any one of the aspects disclosed herein, and a pharmaceutically acceptable carrier. 307 CYTX-115-PCT 4862-0152WO1 [00373] Aspect 53. A nucleic acid encoding the activatable IL12 fusion protein or encoding the first polypeptide or encoding the second polypeptide of the activatable IL12 construct of any one of the aspects disclosed herein. [00374] Aspect 54. A vector comprising the nucleic acid of aspect 53. [00375] Aspect 55. A cell comprising the nucleic acid of aspect 53 or the vector of aspect 54. [00376] Aspect 56. A method of producing the activatable IL12 fusion protein or thefirst polypeptide or the second polypeptide of the activatable IL12 construct of any one of the aspects disclosed herein, comprising culturing the cell of aspect 55 in a culture medium to produce the activatable IL12 fusion protein, thefirst polypeptide, or the second polypeptide; and recovering the activatable IL12 fusion protein, thefirst polypeptide, or the second polypeptide from the culture medium. [00377] Aspect 57. The method of aspect 56, further comprising: purifying the activatable IL12 fusion protein, thefirst polypeptide, or the second polypeptide recovered from the culture medium to obtain a purified activatable IL12 fusion protein,first polypeptide, or second polypeptide. [00378] Aspect 58. A method of treating a subject in need thereof, comprising administering the activatable IL12 fusion protein or the activatable IL12 construct of any one of the aspects disclosed herein to the subject. [00379] Aspect 59. The method of aspect 58, wherein the subject has a cancer, an autoimmune disorder, an inflammatory disorder, or an infectious disease. [00380] Aspect 60. The method of aspect 58 or aspect 59, comprising administering the activatable IL12 fusion protein or the activatable IL12 construct intravenously, intramuscularly, intratumorally, or subcutaneously. [00381] Aspect 61. The method of any one of aspects 58 to 60, further comprising administering a second therapeutic agent. [00382] Aspect 62. The method of aspect 61, wherein the second therapeutic agent is a checkpoint inhibitor, an anti-neoplastic agent, or a cytotoxic agent. [00383] Aspect 63. The method of any one of aspects 61 to 62, wherein the second therapeutic agent is an antibody against PD-L1, an antibody against PD-1, an antibody against CTLA-4, a CD47 antagonist, an ILT2 antagonist, or a SIRPα antagonist to the subject. Aspect 64. An activatable IL12 fusion protein comprising: a first IL12 subunit and a second IL12 subunit; 308 CYTX-115-PCT 4862-0152WO1 at least one of a first linking region (LR1) and a second linking region (LR2); and a half-life extending moiety (EM), wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM), wherein the first IL12 subunit is coupled directly or indirectly to the EM and the second IL-12 subunit is coupled directly or indirectly to the EM, and wherein the first IL12 subunit is coupled to the EM by the LR1, or the first IL12 subunit is coupled to the EM by the LR1 and the second IL12 subunit is coupled to the EM by the LR2. Aspect 65. The activatable IL12 fusion protein of aspect 64, comprising a first polypeptide chain comprising from N-terminus to C-terminus: (i) IL12´-LR1-EM- LR2-IL12″; or (ii) IL12´-IL12″-LR1-EM; wherein the IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond. Aspect 66. The tivatable IL12 fusion protein of any one of aspects 64-65, further comprising a masking moiety (MM). Aspect 67. The activatable IL12 fusion protein of aspect 66, comprising a first polypeptide chain comprising from N-terminus to C-terminus: (i) MM-LR1-IL12´-IL12″-LR2-EM; or (ii) IL12´-IL12″-LR1-MM-LR2-EM. Aspect 68. The activatable IL12 fusion protein of aspect 67, wherein the LR1 and the LR2 comprise a CM. Aspect 69. An activatable IL12 construct comprising the activatable IL12 fusion protein of any one of aspects 64-68, and a second polypeptide chain comprising an EM, wherein the EM of the second polypeptide chain is dimerized with the EM of the activatable IL12 fusion protein. Aspect 70. The activatable IL12 construct of aspect 69, wherein the second polypeptide comprises polypeptide chain comprising from N-terminus to C-terminus: IL12´-LR1-EM- LR2- IL12″. Aspect 71. The activatable IL12 construct of aspect 69, wherein the second polypeptide comprises polypeptide chain comprising from N-terminus to C-terminus: IL12´-CM-LR1-EM- LR2-IL12″. 309 CYTX-115-PCT 4862-0152WO1 Aspect 72. The activatable IL12 construct of any one of aspects 69-71, wherein the EM is an Fc domain, optionally wherein the Fc domain is an IgG Fc domain, and optionally wherein the IgG Fc domain is a human IgG Fc domain, and optionally wherein the Fc domain of the activatable IL12 fusion protein has a different amino acid sequence from the Fc domain of the second polypeptide or wherein the Fc domain of the activatable IL12 fusion protein has the same amino acid sequence as the Fc domain of the second polypeptide. Aspect 73. An activatable IL12 fusion protein or an activatable IL12 construct comprising: a first IL12 subunit and a second IL12 subunit; a first linking region (LR1) and a second linking region (LR2); a half life extension moiety (EM), and a masking moiety (MM); wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM), wherein the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the MM by the LR1 and the MM is coupled to the EM by the LR2, or wherein the first IL12 subunit is coupled to the MM by the LR1, the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the EM by the LR2. Aspect 74. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 72, comprising a first polypeptide chain comprising from N-terminus to C-terminus: (i) MM-LR1-IL12´-IL12″-LR2-EM; or (ii) IL12´-IL12″-LR1-MM-LR2-EM, wherein the IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond. Aspect 75. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 73, wherein the activatable construct comprises a second polypeptide comprising an EM. Aspect 76. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 74, wherein the EM of the first polypeptide chain and the second EM of the second polypeptide chain form a dimer. Aspect P. The activatable IL12 fusion protein of aspect 76, comprising afirst polypeptide having a structure N'-EM1-LR1-IL12’-C' or C'-EM1-LR1-IL12’-N'; and a second polypeptide having a structure N'-EM2-LR2-IL12”-LR3-MM-C' or C'-EM2-LR2-IL12”-LR3-MM-N', wherein EM1 is 310 CYTX-115-PCT 4862-0152WO1 a first half life extension moiety, EM2 is second half life extension moiety, and LR3 is a third linking region. Aspect Q. The activatable IL12 fusion protein of aspect P, wherein LR1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. Aspect R. The activatable IL12 fusion protein of aspect Q, wherein LR2 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. Aspect S. The activatable IL12 fusion protein of aspect Q, wherein LR3 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. Aspect T. The activatable IL12 fusion protein of aspect 76, comprising afirst polypeptide having a structure N'-EM1-LR1-IL12’-LR2-MM-C' or C'-EM1-LR1-IL12’-LR2-MM-N'; and a second polypeptide having a structure N'-EM2-LR3-IL12”-C' or C'-EM2-LR3-IL12”-N', wherein EM1 is a first half life extension moiety, EM2 is second half life extension moiety, and LR3 is a third linking region. Aspect U. The activatable IL12 fusion protein of aspect T, wherein LR1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. Aspect V. The activatable IL12 fusion protein of aspect T, wherein LR2 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. Aspect W. The activatable IL12 fusion protein of aspect 8T, wherein LR3 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 311 CYTX-115-PCT 4862-0152WO1 Aspect X. The activatable IL12 fusion protein or an activatable IL12 construct of aspect W, comprising a first cleavable moiety (CM1), a second cleavable moiety (CM2), and a third cleavable moiety (CM3). Aspect Y. The activatable IL12 fusion protein or an activatable IL12 construct of aspect X, having a structure comprising from N-terminus to C-terminus: i) IL12’-CM1-EM1; and ii) MM-CM2-IL12”-CM3-EM2; or wherein the IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond. Aspect 77. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64 to 75, wherein the first IL12 subunit is p40 and the second IL12 subunit is p35 or wherein the first IL12 subunit is p35 and the second IL12 subunit is p40. Aspect 78. An activatable IL12 fusion protein or an activatable IL12 construct comprising: a) N´-p35-EM-CM-p40-C´; b) N´-p40-EM-CM-p35-C´; c) N´-p35-CM-EM-p40-C´; d) N´-p40-CM-EM-p35-C´; e) N´-p40-p35-CM-EM-C´; f) N´-p40-p35-CM-MM-EM-C´; or g) a dimer of any combination of two polypeptides of one or two of a)-d), wherein p35 is an IL12α domain, wherein p40 is an IL12β domain, wherein CM is a cleavable moiety, wherein EM is a half-life extending moiety, wherein N´ represents the N-terminus, wherein C´ represents the C-terminus, wherein MM is a masking moiety, and wherein “-” comprises a linker or a direct bond. Aspect 79. The activatable IL12 construct of aspect 78, comprising a dimer of: i) a first polypeptide comprising a) and a second polypeptide comprising a); ii) a first polypeptide comprising b) and a second polypeptide comprising b); 312 CYTX-115-PCT 4862-0152WO1 iii) a first polypeptide comprising c) and a second polypeptide comprising c); iv) a first polypeptide comprising d) and a second polypeptide comprising d); v) a first polypeptide comprising a) and a second polypeptide comprising b); vi) a first polypeptide comprising a) and a second polypeptide comprising c); vii) a first polypeptide comprising a) and a second polypeptide comprising d); viii) a first polypeptide comprising b) and a second polypeptide comprising c); ix) a first polypeptide comprising b) and a second polypeptide comprising d); or x) a first polypeptide comprising c) and a second polypeptide comprising d), wherein the EM of the first polypeptide and the EM of the second polypeptide are dimerized. Aspect 80. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 78, wherein e) further comprises a MM and a second cleavable moiety (CM2) such that it comprises a structural arrangement of: N´-MM-CM2-p40-p35-CM-EM-C´. Aspect 81. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 78, wherein f) further comprises a second cleavable moiety (CM2) such that it comprises a structural arrangement of: N´-p40-p35-CM-MM-CM2-EM-C´. Aspect 82. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 78-81, further comprising at least one of a first linking region (LR1) and a second linking region (LR2). Aspect 83. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 82, comprising: a) N´-p35-LR1-EM-LR2-CM-p40-C´; b) N´-p35-EM-LR1-CM-p40-C´; c) N´-p35-LR1-EM-CM-p40-C´; d) N´-p40-LR1-EM-LR2-CM-p35-C´; e) N´-p40-EM-LR1-CM-p35-C´; f) N´-p40-LR1-EM-CM-p35-C´; g) N´-p35-CM-LR1-EM-LR2-p40-C´; h) N´-p35-CM-EM-LR1-p40-C´; i) N´-p35-CM-LR1-EM-p40-C´; j) N´-p40-LR1-CM-EM-LR2-p35-C´; k) N´-p40-CM-EM-LR1-p35-C´; 313 CYTX-115-PCT 4862-0152WO1 l) N´-p40-LR1-CM-EM-p35-C´; m) N´-p40-p35-CM-LR1-EM-C´; n) N´-p40-p35-CM-LR1-MM-LR2-EM-C´; or o) a dimer of any combination of two polypeptides of one or two of a)-n). Aspect 84. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-77 and 82-83, wherein the LR1, the LR2, or both the LR1 and the LR2 are each independently 7 to 45 amino acids amino acids in length. Aspect 85. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-77 and 82-83, wherein the LR1 and the LR2 are each independently at least 7 amino acids amino acids in length. Aspect 86. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 85, wherein the LR1 and the LR2 are each independently 7 to 300 amino acids amino acids in length. Aspect 87. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-77 and 82-83, wherein the LR1 and the LR2 are each independently 1 to 300 amino acids in length. Aspect 88. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 87, wherein the LR1 and the LR2 are each independently 1 to 60 amino acids in length. Aspect 89. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 88, wherein the LR1 and the LR2 are each independently 4 to 50 amino acids in length. Aspect 90. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 89, wherein the LR1 and the LR2 are each independently 4 to 43 amino acids in length. Aspect 91. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 90, wherein the LR1 and the LR2 are each independently 29 to 43 amino acids in length. Aspect 92. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 90, wherein the LR1 and the LR2 are each independently 17 to 21 amino acids in length. Aspect 93. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-92, wherein the EM is selected from a polyalkylene glycol polymer, a hexa-hat GST (glutathione S-transferase) glutathione affinity, Calmodulin-binding peptide (CBP), Strep-tag, Cellulose Binding Domain, Maltose Binding Protein, S-Peptide Tag, Chitin Binding Tag, Immuno-reactive Epitopes, Epitope Tags, E2Tag, HA Epitope Tag, Myc Epitope, FLAG 314 CYTX-115-PCT 4862-0152WO1 Epitope, AU1 and AU5 Epitopes, Glu-Glu Epitope, KT3 Epitope, IRS Epitope, Btag Epitope, Protein Kinase-C Epitope, VSV Epitope, a latency associated protein (LAP), or a serum albumin protein. Aspect 94. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 93, wherein the EM is human serum albumin (HSA). Aspect 95. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 93, wherein the EM is an albumin binding peptide comprising the amino acid sequence QRLMEDICLPRWGCLWEDDF (SEQ ID NO: 1424). Aspect 96. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-92, wherein the EM is a dimerization domain (DD). Aspect 97. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 96, wherein the DD is an IgG Fc domain, optionally wherein the IgG Fc domain is a human IgG Fc domain. Aspect 98. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 97, wherein the Fc domain is covalently bound to a second Fc domain via at least one disulfide bond thereby forming a dimer. Aspect 99. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-77 and 82-98, wherein at least one of the LR1 and the LR2 comprises a CM. Aspect 100. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-99, wherein the CM is a substrate for a matrix metalloprotease (MMP) or a serine protease, or both. Aspect 101. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 100, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14. Aspect 102. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-99, wherein the CM comprises an amino acid sequence of QXAQX1LX2XBA (SEQ ID NO: 1388), wherein XA is N, A, W, or F; X1 is G or A; X2 is R or K; XB is S, M, V, or L, provided that: i) when XA is N, then XB is S, L, or V; ii) when XA is A, then XB is S or M; and iii) when XA is W or F, then XB is M; and wherein the CM is a substrate for a protease. 315 CYTX-115-PCT 4862-0152WO1 Aspect 103. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 102, wherein the CM comprises a sequence selected from: SEQ ID NO: 1389, SEQ ID NO: 1394, SEQ ID NO: 1399, SEQ ID NO: 1404, SEQ ID NO: 1409, SEQ ID NO: 1414, SEQ ID NO: 1419. Aspect 104. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 102, wherein the CM comprises a sequence selected from: SEQ ID NO: 1390, SEQ ID NO: 1391, SEQ ID NO: 1392, SEQ ID NO: 1393, SEQ ID NO: 1395, SEQ ID NO: 1396, SEQ ID NO: 1397, SEQ ID NO: 1398, SEQ ID NO: 1400, SEQ ID NO: 1401, SEQ ID NO: 1402, SEQ ID NO: 1403, SEQ ID NO: 1405, SEQ ID NO: 1406, SEQ ID NO: 1407, SEQ ID NO: 1408, SEQ ID NO: 1410, SEQ ID NO: 1411, SEQ ID NO: 1412, SEQ ID NO: 1413, SEQ ID NO: 1415, SEQ ID NO: 1416, SEQ ID NO: 1417, SEQ ID NO: 1418, SEQ ID NO: 1420, SEQ ID NO: 1421, SEQ ID NO: 1422, or SEQ ID NO: 1423. Aspect 105. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 64-99, wherein the CM comprises SEQ ID NO: 428, SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 1354, SEQ ID NO: 805, SEQ ID NO: 1278, SEQ ID NO: 144. Aspect 106. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 105, wherein the CM comprises SEQ ID NO: 428 or SEQ ID NO: 805. Aspect 107. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 68-92 and 96-106, wherein the MM is an Fab, an Fab fragment, a receptor polypeptide of the receptor for the IL12, or an extracellular domain of the IL12 receptor. Aspect 108. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 107, wherein the Fab fragment is an scFv. Aspect 109. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 68-92 and 96-108, wherein the MM comprises a HCDR1 sequence comprising SYGMH (SEQ ID NO: 1355), a HCDR2 sequence comprising FIRYDGSNKYYADSVKG (SEQ ID NO: 1356), a HCDR3 sequence comprising HGSHDN (SEQ ID NO: 1357), a LCDR1 sequence comprising SGSRSNIGSNTVK (SEQ ID NO: 1358), a LCDR2 sequence comprising YNDQRPS (SEQ ID NO: 1359), and LCDR3 sequence comprising QSYDRYTHPALL (SEQ ID NO: 1360). Aspect 110. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 109, wherein the MM comprises SEQ ID NO: 1361, SEQ ID NO: 1362, or both. 316 CYTX-115-PCT 4862-0152WO1 Aspect 111. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 108, wherein the MM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1355-1362, 1426-1433, or a combination thereof. Aspect 112. The activatable IL12 fusion protein or the activatable IL12 construct of any one of aspects 68-111, wherein the MM is less than 300 amino acids in length. Aspect 113. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 112, wherein the MM is about 400 to about 900 amino acids in length. Aspect 114. The activatable IL12 fusion protein or the activatable IL12 construct of aspect 113, wherein the MM is an scFv comprising an amino acid sequence according to SEQ ID NO: 289. [00384] According to any one or combination of the foregoing aspects, a linker between the p40 domain and the p35 domain is 7, 8, 9, 10, 11, 12, 13, 14, or 15 amino acids in length, e.g., 7 amino acids or 15 amino acids. [00385] According to any one or combination of the foregoing aspects, a linking region (flexible linker or flexible linker and CM) between the MM and the IL12 is 25 to 47 amino acids in length (including any integer in the range of 25 to 47), e.g., 25, 38, or 47 amino acids. [00386] According to any one or combination of the foregoing aspects, a linking region (flexible linker or flexible linker and CM) between the MM and the DD is 25 to 47 amino acids in length (including any integer in the range of 25 to 47), e.g., 25, 38, or 47 amino acids. [00387] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 246, SEQ ID NO: 247, SEQ ID NO: 1354, SEQ ID NO: 805, SEQ ID NO: 1278, and SEQ ID NO: 144. [00388] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 318-1347 [00389] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 318-331. [00390] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 332-400. [00391] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 401-794. [00392] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 795-1274. 317 CYTX-115-PCT 4862-0152WO1 [00393] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1275-1347. [00394] According to any one or combination of the foregoing aspects, the CM comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1388-1423. OTHER EMBODIMENTS [00395] It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims. 318

Claims

CYTX-115-PCT 4862-0152WO1 CLAIMS 1. An activatable interleukin 12 (IL12) fusion protein comprising afirst polypeptide having a structure selected from: i) N'-DD-L1-MM-L2-IL12-C', ii) C'-DD-L1-MM-L2-IL12-N', iii) N'-DD-L1-IL12-L2-MM-C', or iv) C'-DD-L1-IL12-L2-MM-N', wherein: a) L1 is afirst linker or is absent; b) L2 is a second linker; c) DD is a dimerization domain; d) MM is a masking moiety; e) IL12 comprises an IL12α (p35) domain and an IL12β (p40) domain; f) N' is an amino terminus of the activatable IL12 fusion protein; and g) C' is a carboxy terminus of the activatable IL12 fusion protein, wherein at least one of L1 and L2 comprises a cleavable moiety (CM). 2. The activatable IL12 fusion protein of claim 1, wherein the activatable IL12 fusion protein has 1.5-fold to about 1000-fold, or about 2-fold to about 100-fold, or about 100-fold to about 1000-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. 3. The activatable IL12 fusion protein of claim 1, wherein the fusion protein comprises a second polypeptide comprising a second dimerization domain (DD2), and wherein the DD and the DD2 are dimerized. 4. The activatable IL12 fusion protein of claim 3, wherein the dimer is not a homodimer. 5. The activatable IL12 fusion protein of any one of claims 1 to 4, wherein the L2 comprises a CM, and the L1 is absent or the L1 does not comprise a CM. 6. The activatable IL12 fusion protein of any one of claims 1 to 5, wherein L1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 319 CYTX-115-PCT 4862-0152WO1 7. The activatable IL12 fusion protein of any one of claims 1 to 6, wherein L2 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids. 8. The activatable IL12 fusion protein of any one of claims 3 to 4, having a structure comprising: i) C'-DD1-L1-MM-CM-IL12-N', and DD2; or ii) N'-DD1-L1-MM-CM-IL12-C', and DD2. 9. The activatable IL12 fusion protein of any one of claims 3 to 4, wherein the CM is a first cleavable moiety (CM1) and further comprising a second cleavable moiety (CM2). 10. The activatable IL12 fusion protein of claim 9, having a structure comprising: i) C'-DD1-CM1-IL12-CM2-MM-N', and DD2; ii) N'-DD1-CM1-IL12-CM2-MM-C', and DD2; iii) C'-DD1-CM1-MM-CM2-IL12-N', and DD2; or vi) N'-DD1-CM1-MM-CM2-IL12-C', and DD2. 11. The activatable IL12 fusion protein of claim 9, further comprising a third cleavable moiety (CM3). 12. The activatable IL12 fusion protein of claim 11, having a structure comprising: i) C'-DD1-CM1-MM-CM2-IL12-N', and DD2; or ii) N'-DD1-CM1-MM-CM2-IL12-C', and DD2, 320 CYTX-115-PCT 4862-0152WO1 wherein the MM comprises a first sequence (MM’) and a second sequence (MM”), and wherein the MM further comprises the CM3 within the MM sequence according to the structure comprising: MM’-CM3-MM”. 13. The activatable IL12 fusion protein of claim 3 or claim 4, comprising afirst polypeptide having a structure N'-DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2-IL12-N', and a second polypeptide having a N'-DD2-L3-MM2-L4-IL12-C' or C'-DD2-L3-MM2-L4-IL12-N', wherein MM1 is a first masking moiety, MM2 is a second masking moiety, L3 is a third linker, and L4 is a fourth linker. 14. The activatable IL12 fusion protein of claim 13, wherein L1 and L3 comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 15. The activatable IL12 fusion protein of claim 13 or claim 14, wherein L2 and L4 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids. 16. The activatable IL12 fusion protein of claim 13, wherein the CM is a first cleavable moiety (CM1) and further comprising a second cleavable moiety (CM2), a third cleavable moiety (CM3), and a fourth cleavable moiety (CM4), and having a structure comprising: i) C'-DD1-CM1-MM1-CM2-IL12-N', and C'-DD2-CM3-MM2-CM4-IL12-N'; or ii) N'-DD1-CM1-MM1-CM2-IL12-C', and N'-DD2-CM3-MM2-CM4-IL12-C'. 17. The activatable IL12 fusion protein of claim 3 or claim 4, comprising afirst polypeptide having a structure N'-DD1-L1-MM1-L2-IL12-C' or C'-DD1-L1-MM1-L2-IL12-N'; and a second polypeptide having a structure N'-DD2-L3-MM2-C' or C'-DD2-L3-MM2-N', wherein MM1 is a first masking moiety, MM2 is a second masking moiety, and L3 is a third linker, wherein the MM1 comprises a first sequence (MM1’) and a second sequence (MM1”), and wherein the MM1 further comprises a second cleavable moiety (CM2) within the MM1 according to the structure comprising: MM1’-CM2-MM1”. 321 CYTX-115-PCT 4862-0152WO1 18. The activatable IL12 fusion protein of claim 17, wherein L1 and L3 comprise about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 19. The activatable IL12 fusion protein of claim 17 or claim 18, wherein L2 comprises about 26 amino acids to about 54 amino acids, about 28 amino acids to about 52 amino acids, about 30 amino acids to about 50 amino acids, or about 32 amino acids to about 48 amino acids. 20. The activatable IL12 fusion protein of claim 3 or claim 4, wherein the CM is a first cleavable moiety (CM1) and further comprising a second cleavable moiety (CM2), a third cleavable moiety (CM3), and a fourth cleavable moiety (CM4), and having a structure comprising: i) C'-DD1-CM1-MM1-CM2-IL12-N', and C’DD2-CM3-MM2-N’; or ii) N'-DD1-CM1-MM1-CM2-IL12-C', and N’-DD2-CM3-MM2-N’ wherein the MM1 comprises a first sequence (MM1’) and a second sequence (MM1”), and wherein the MM1 further comprises the CM4 within the MM1 according to the structure comprising: MM1’-CM4-MM1”. 21. The activatable IL12 fusion protein of any one of claims 1 to 7, wherein at least one of the L1 and the L2 comprises a CM that is a substrate for a matrix metalloprotease (MMP) or a serine protease, or both. 22. The activatable IL12 fusion protein of claim 21, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14. 23. The activatable IL12 fusion protein of any one of claims 3 to 22, wherein the DD or the DD2 is an IgG Fc domain, optionally wherein the IgG Fc domain is a human IgG Fc domain. 24. The activatable IL12 fusion protein of any one of claims 3 to 23, wherein the DD and the DD2 are covalently bound to each other via at least one disulfide bond thereby forming a dimer. 322 CYTX-115-PCT 4862-0152WO1 25. The activatable IL12 fusion protein of any one of claims 1 to 24, wherein the IL12 comprises a linker between the p35 domain and the p40 domain. 26. The activatable IL12 fusion protein of any one of claims 1 to 25, wherein the DD is more proximal to the p35 domain than to the p40 domain. 27. The activatable IL12 fusion protein of any one of claims 1 to 26 wherein the DD is at the amino terminal end of thefirst polypeptide, and IL12 is at the carboxy terminal end of thefirst polypeptide. 28. The activatable IL12 fusion protein of any one of claims 1 to 26, wherein the DD is at the carboxy terminal end of thefirst polypeptide, and IL12 is at the amino terminal end of thefirst polypeptide. 29. The activatable IL12 fusion protein of any one of claims 1 to 7, wherein the L2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 58 to 98, 101 to 282, 318-1354, and 1388-1423. 30. The activatable IL12 fusion protein of claim 29, wherein the L1 is absent or comprises an amino acid sequence independently selected from the group consisting of SEQ ID NOs: 58 to 98, 101 to 282, 318-1354, and 1388-1423. 31. The activatable IL12 fusion protein of any one of claims 1 to 30, wherein the MM is less than 300 amino acids in length. 32. The activatable IL12 fusion protein of any one of claims 1 to 30, wherein the MM is about 400 to about 900 amino acids in length. 33. The activatable IL12 fusion protein of any one of claims 1 to 32, wherein the activatable IL12 fusion protein has about 100-fold to about 500-fold less IL12 activity than a cleavage product of the activatable IL12 fusion protein in an IL12 reporter assay. 34. The activatable IL12 fusion protein of claim 33, wherein the activatable IL12 fusion protein has about 200-fold to about 500-fold less IL12 activity than a cleavage product of the activatable IL12 fusion protein in an IL12 reporter assay. 323 CYTX-115-PCT 4862-0152WO1 35. The activatable IL12 fusion protein of any one of claims 1 to 32, wherein thefirst polypeptide comprises SEQ ID NO: 1 and the second polypeptide comprises SEQ ID NO: 2. 36. The activatable IL12 fusion protein of any one of claims 1 to 32, wherein a) thefirst polypeptide comprises SEQ ID NO: 7 and the second polypeptide comprises SEQ ID NO: 8; b) thefirst polypeptide comprises SEQ ID NO: 9 and the second polypeptide comprises SEQ ID NO: 10; c) thefirst polypeptide comprises SEQ ID NO: 11 and the second polypeptide comprises SEQ ID NO: 12; d) thefirst polypeptide comprises SEQ ID NO: 13 and the second polypeptide comprises SEQ ID NO: 14; e) thefirst polypeptide comprises SEQ ID NO: 15 and the second polypeptide comprises SEQ ID NO: 16; or f) thefirst polypeptide comprises SEQ ID NO: 17 and the second polypeptide comprises SEQ ID NO: 18. 37. An activatable IL12 construct comprising: i) afirst polypeptide having a structure N'-DD1-L1-p40-C' or C'-DD1-L1-p40-N', and a second polypeptide having a structure N'-DD2-L2-p35-L3-MM-C' or C'-DD2-L2-p35- L3-MM-N'; or ii) afirst polypeptide having a structure N'-DD1-L1-p35-C' or C'-DD1-L1-p35-N' and a second polypeptide having a structure N'-DD2-L2-p40-L3-MM-C' or C'-DD2-L2-p40- L3-MM-N', wherein: a) each of L1, L2, and L3 independently comprises a cleavable moiety (CM); b) DD1 is afirst dimerization domain and DD2 is a second dimerization domain, wherein DD1 and DD2 are dimerized; c) MM is a masking moiety; d) N' is an amino terminus; e) C' is a carboxy terminus; and wherein the activatable IL12 construct has about 50-fold to about 1000-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. 324 CYTX-115-PCT 4862-0152WO1 38. The activatable IL12 construct of claim 37, wherein the CM is a substrate for an MMP or a serine protease, or both. 39. The activatable IL12 construct of claim 37 or claim 38, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14. 40. The activatable IL12 construct of any one of claims 37 to 39, wherein the DD1 is at the amino terminal end of each of thefirst polypeptide and the second polypeptide. 41. The activatable IL12 construct of any one of claims 37 to 39, wherein the DD1 is at the carboxy terminal end of each of thefirst polypeptide and the second polypeptide. 42. The activatable IL12 construct of any one of claims 37 to 41, wherein each of the L1, the L2, and the L3 independently comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 61 to 98. 43. The activatable IL12 fusion protein of any one of claims 37 to 42, wherein the MM is less than 300 amino acids in length. 44. The activatable IL12 construct of any one of claims 37 to 42, wherein the MM is about 400 to about 900 amino acids in length. 45. The activatable IL12 construct of any one of claims 38 to 44, has about 50-fold to about 150-fold less IL12 activity than a cleavage product of the activatable IL12 construct in an IL12 reporter assay. 46. The activatable IL12 construct of any one of claims 37 to 41, wherein a) thefirst polypeptide comprises SEQ ID NO: 3 and the second polypeptide comprises SEQ ID NO: 4; b) thefirst polypeptide comprises SEQ ID NO: 19 and the second polypeptide comprises SEQ ID NO: 20; c) thefirst polypeptide comprises SEQ ID NO: 21 and the second polypeptide comprises SEQ ID NO: 22; d) thefirst polypeptide comprises SEQ ID NO: 23 and the second polypeptide comprises SEQ ID NO: 24; e) thefirst polypeptide comprises SEQ ID NO: 25 and the second polypeptide comprises SEQ ID NO: 26; 325 CYTX-115-PCT 4862-0152WO1 f) thefirst polypeptide comprises SEQ ID NO: 27 and the second polypeptide comprises SEQ ID NO: 28; g) thefirst polypeptide comprises SEQ ID NO: 29 and the second polypeptide comprises SEQ ID NO: 30; h) thefirst polypeptide comprises SEQ ID NO: 31 and the second polypeptide comprises SEQ ID NO: 32; i) thefirst polypeptide comprises SEQ ID NO: 33 and the second polypeptide comprises SEQ ID NO: 34; j) thefirst polypeptide comprises SEQ ID NO: 35 and the second polypeptide comprises SEQ ID NO: 36; k) thefirst polypeptide comprises SEQ ID NO: 37 and the second polypeptide comprises SEQ ID NO: 38; l) thefirst polypeptide comprises SEQ ID NO: 39 and the second polypeptide comprises SEQ ID NO: 40; m) thefirst polypeptide comprises SEQ ID NO: 41 and the second polypeptide comprises SEQ ID NO: 42; n) thefirst polypeptide comprises SEQ ID NO: 43 and the second polypeptide comprises SEQ ID NO: 44; o) thefirst polypeptide comprises SEQ ID NO: 45 and the second polypeptide comprises SEQ ID NO: 46; p) thefirst polypeptide comprises SEQ ID NO: 47 and the second polypeptide comprises SEQ ID NO: 48; q) thefirst polypeptide comprises SEQ ID NO: 49 and the second polypeptide comprises SEQ ID NO: 50; or r) thefirst polypeptide comprises SEQ ID NO: 51 and the second polypeptide comprises SEQ ID NO: 52. 47. An activatable IL12 construct comprising afirst polypeptide having a structure N'-DD1-L1- IL12-C' or C'-DD1-L1-IL12-N'; and a second polypeptide having a structure N'-DD2-L2-MM-C' or C'-DD2-L2-MM-N', wherein: a) IL12 comprises a p35 domain and a p40 domain; b) each of L1 and L2 independently is a cleavable moiety (CM); 326 CYTX-115-PCT 4862-0152WO1 c) DD1 is afirst dimerization domain and DD2 is a second dimerization domain, wherein DD1 and DD2 are dimerized; d) MM is a masking moiety; e) N' is an amino terminus; f) C' is an carboxy terminus; and g) the DD1 is more proximal to the p35 domain than to the p40 domain; and wherein the activatable IL12 construct has about 10-fold to about 50-fold less IL12 activity than recombinant human IL12 polypeptide in an IL12 reporter assay. 48. The activatable IL12 fusion protein of claim 47, wherein L1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 49. The activatable IL12 fusion protein of claim 47 or claim 48, wherein L2 comprises about 20 amino acids to about 60 amino acids, about 22 amino acids to about 58 amino acids, or about 24 amino acids to about 56 amino acids. 50. The activatable IL12 construct of claim 47, wherein the CM is a substrate for an MMP or a serine protease, or both. 51. The activatable IL12 construct of claim 50, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14. 52. The activatable IL12 construct of any one of claims 47 to 51, wherein the IL12 comprises a linker between the p35 domain and the p40 domain. 53. The activatable IL12 construct of any one of claims 47 to 52, wherein the DD1 is at the carboxy terminal end of thefirst polypeptide and the DD2 is at the carboxy terminal end of the second polypeptide. 54. The activatable IL12 construct of any one of claims 47 to 53, wherein each of the L1 and the L2 independently comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 61 to 98. 327 CYTX-115-PCT 4862-0152WO1 55. The activatable IL12 fusion protein of any one of claims 47 to 54, wherein the MM is less than 300 amino acids in length. 56. The activatable IL12 construct of any one of claims 47 to 54, wherein the MM is about 400 to about 900 amino acids in length. 57. The activatable IL12 construct of any one of claims 47 to 56, has about 100-fold to about 5- fold to 20-fold less IL12 activity than a cleavage product of the activatable IL12 construct in an IL12 reporter assay. 58. The activatable IL12 construct of any one of claims 47 to 57, wherein thefirst polypeptide comprises SEQ ID NO: 5 and the second polypeptide comprises SEQ ID NO: 6. 59. A composition comprising the activatable IL12 fusion protein of any one of claims 1 to 26 or the activatable IL12 construct of any one of claims 37 to 58, and a pharmaceutically acceptable carrier, or a container, vial, syringe, injector pen, or a kit comprising the activatable IL12 fusion protein of any one of claims 1 to 36 or the activatable IL12 construct of any one of claims 37 to 58, and a pharmaceutically acceptable carrier. 60. A nucleic acid encoding the activatable IL12 fusion protein of any one of claims 1 to 36, or encoding thefirst polypeptide or encoding the second polypeptide of the activatable IL12 construct of any one of claims 37 to 58. 61. A vector comprising the nucleic acid of claim 60. 62. A cell comprising the nucleic acid of claim 60 or the vector of claim 61. 63. A method of producing the activatable IL12 fusion protein of any one of claims 1 to 26, or thefirst polypeptide or the second polypeptide of the activatable IL12 construct of any one of claims 37 to 58, comprising culturing the cell of claim 62 in a culture medium to produce the activatable IL12 fusion protein, thefirst polypeptide, or the second polypeptide; and recovering the activatable IL12 fusion protein, thefirst polypeptide, or the second polypeptide from the culture medium. 328 CYTX-115-PCT 4862-0152WO1 64. The method of claim 63, further comprising: purifying the activatable IL12 fusion protein, thefirst polypeptide, or the second polypeptide recovered from the culture medium to obtain a purified activatable IL12 fusion protein,first polypeptide, or second polypeptide. 65. A method of treating a subject in need thereof, comprising administering the activatable IL12 fusion protein of any one of claims 1 to 36 or the activatable IL12 construct of any one of claims 37 to 58 to the subject. 66. The method of claim 65, wherein the subject has a cancer, an autoimmune disorder, an inflammatory disorder, or an infectious disease. 67. The method of claim 65 or claim 66, comprising administering the activatable IL12 fusion protein or the activatable IL12 construct intravenously, intramuscularly, intratumorally, or subcutaneously. 68. The method of any one of claims 65 to 67, further comprising administering a second therapeutic agent. 69. The method of claim 68, wherein the second therapeutic agent is a checkpoint inhibitor, an anti-neoplastic agent, or a cytotoxic agent. 70. The method of any one of claims 68 to 69, wherein the second therapeutic agent is an antibody against PD-L1, an antibody against PD-1, an antibody against CTLA-4, a CD47 antagonist, an ILT2 antagonist, or a SIRPα antagonist to the subject. 71. An activatable IL12 fusion protein comprising: a first IL12 subunit and a second IL12 subunit; at least one of a first linking region (LR1) and a second linking region (LR2); and a half-life extending moiety (EM), wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM), wherein the first IL12 subunit is coupled directly or indirectly to the EM and the second IL-12 subunit is coupled directly or indirectly to the EM, and wherein the first IL12 subunit is coupled to the EM by the LR1, or the first IL12 subunit is coupled to the EM by the LR1 and the second IL12 subunit is coupled to the EM by the LR2. 329 CYTX-115-PCT 4862-0152WO1 72. The activatable IL12 fusion protein of claim 71, comprising a first polypeptide chain comprising from N-terminus to C-terminus: (i) IL12´-LR1-EM- LR2-IL12″; or (ii) IL12´-IL12″-LR1-EM; wherein the IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond. 73. The activatable IL12 fusion protein of any one of claims 71-72, further comprising a masking moiety (MM). 74. The activatable IL12 fusion protein of claim 73, comprising a first polypeptide chain comprising from N-terminus to C-terminus: (i) MM-LR1-IL12´-IL12″-LR2-EM; or (ii) IL12´-IL12″-LR1-MM-LR2-EM. 75. The activatable IL12 fusion protein of claim 74, wherein the LR1 and the LR2 comprise a CM. 76. An activatable IL12 construct comprising the activatable IL12 fusion protein of any one of claims 71-75, and a second polypeptide chain comprising an EM, wherein the EM of the second polypeptide chain is dimerized with the EM of the activatable IL12 fusion protein. 77. The activatable IL12 construct of claim 76, wherein the second polypeptide comprises polypeptide chain comprising from N-terminus to C-terminus: IL12´-LR1-EM-LR2-IL12″. 78. The activatable IL12 construct of claim 76, wherein the second polypeptide comprises polypeptide chain comprising from N-terminus to C-terminus: IL12´-CM-LR1-EM-LR2-IL12″. 79. The activatable IL12 construct of any one of claims 76-78, wherein the EM is an Fc domain, optionally wherein the Fc domain is an IgG Fc domain, and optionally wherein the IgG Fc domain is a human IgG Fc domain, and optionally wherein the Fc domain of the activatable IL12 fusion protein has a different amino acid sequence from the Fc domain of the second polypeptide or wherein the Fc domain of the activatable IL12 fusion protein has the same amino acid sequence as the Fc domain of the second polypeptide. 80. An activatable IL12 fusion protein or an activatable IL12 construct comprising: a first IL12 subunit and a second IL12 subunit; a first linking region (LR1) and a second linking region (LR2); 330 CYTX-115-PCT 4862-0152WO1 a half life extension moiety (EM), and a masking moiety (MM); wherein at least one of the LR1 and the LR2 comprises a cleavable moiety (CM), wherein the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the MM by the LR1 and the MM is coupled to the EM by the LR2, or wherein the first IL12 subunit is coupled to the MM by the LR1, the first IL12 subunit is coupled to the second IL12 subunit and the second IL12 subunit is coupled to the EM by the LR2. 81. The activatable IL12 fusion protein or the activatable IL12 construct of claim 80, comprising a first polypeptide chain comprising from N-terminus to C-terminus: (i) MM-LR1-IL12´-IL12″-LR2-EM; or (ii) IL12´-IL12″-LR1-MM-LR2-EM, wherein the IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond. 82. The activatable IL12 fusion protein or the activatable IL12 construct of claim 80, wherein the activatable construct comprises a second polypeptide comprising an EM. 83. The activatable IL12 fusion protein or the activatable IL12 construct of claim 82, wherein the EM of the first polypeptide chain and the second EM of the second polypeptide chain form a dimer. 84. The activatable IL12 fusion protein of claim 83, comprising afirst polypeptide having a structure N'-EM1-LR1-IL12’-C' or C'-EM1-LR1-IL12’-N'; and a second polypeptide having a structure N'-EM2-LR2-IL12”-LR3-MM-C' or C'-EM2-LR2-IL12”-LR3-MM-N', wherein EM1 is a first half life extension moiety, EM2 is second half life extension moiety, and LR3 is a third linking region. 85. The activatable IL12 fusion protein of claim 84, wherein LR1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 86. The activatable IL12 fusion protein of claim 84, wherein LR2 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino 331 CYTX-115-PCT 4862-0152WO1 acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 87. The activatable IL12 fusion protein of claim 84, wherein LR3 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 88. The activatable IL12 fusion protein of claim 83, comprising afirst polypeptide having a structure N'-EM1-LR1-IL12’-LR2-MM-C' or C'-EM1-LR1-IL12’-LR2-MM-N'; and a second polypeptide having a structure N'-EM2-LR3-IL12”-C' or C'-EM2-LR3-IL12”-N', wherein EM1 is a first half life extension moiety, EM2 is second half life extension moiety, and LR3 is a third linking region. 89. The activatable IL12 fusion protein of claim 88, wherein LR1 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 90. The activatable IL12 fusion protein of claim 88, wherein LR2 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 91. The activatable IL12 fusion protein of claim 88, wherein LR3 comprises about 10 amino acids to about 30 amino acids, about 11 amino acids to about 28 amino acids, about 12 amino acids to about 26, about 13 amino acids to about 24 amino acids, or about 14 amino acids to about 22 amino acids. 92. The activatable IL12 fusion protein or an activatable IL12 construct of claim 91, comprising a first cleavable moiety (CM1), a second cleavable moiety (CM2), and a third cleavable moiety (CM3). 93. The activatable IL12 fusion protein or an activatable IL12 construct of claim 92, having a structure comprising from N-terminus to C-terminus: 332 CYTX-115-PCT 4862-0152WO1 i) IL12’-CM1-EM1; and ii) MM-CM2-IL12”-CM3-EM2; or wherein the IL12´ is the first IL12 subunit and the IL12″ is the second IL12 subunit, and wherein “-” comprises a linker or a direct bond. 94. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71 to 93, wherein the first IL12 subunit is p40 and the second IL12 subunit is p35 or wherein the first IL12 subunit is p35 and the second IL12 subunit is p40. 95. An activatable IL12 fusion protein or an activatable IL12 construct comprising: a) N´-p35-EM-CM-p40-C´; b) N´-p40-EM-CM-p35-C´; c) N´-p35-CM-EM-p40-C´; d) N´-p40-CM-EM-p35-C´; e) N´-p40-p35-CM-EM-C´; f) N´-p40-p35-CM-MM-EM-C´; or g) a dimer of any combination of two polypeptides of one or two of a)-d), wherein p35 is an IL12α domain, wherein p40 is an IL12β domain, wherein CM is a cleavable moiety, wherein EM is a half-life extending moiety, wherein N´ represents the N-terminus, wherein C´ represents the C-terminus, wherein MM is a masking moiety, and wherein “-” comprises a linker or a direct bond. 96. The activatable IL12 construct of claim 95, comprising a dimer of: i) a first polypeptide comprising a) and a second polypeptide comprising a); ii) a first polypeptide comprising b) and a second polypeptide comprising b); iii) a first polypeptide comprising c) and a second polypeptide comprising c); iv) a first polypeptide comprising d) and a second polypeptide comprising d); 333 CYTX-115-PCT 4862-0152WO1 v) a first polypeptide comprising a) and a second polypeptide comprising b); vi) a first polypeptide comprising a) and a second polypeptide comprising c); vii) a first polypeptide comprising a) and a second polypeptide comprising d); viii) a first polypeptide comprising b) and a second polypeptide comprising c); ix) a first polypeptide comprising b) and a second polypeptide comprising d); or x) a first polypeptide comprising c) and a second polypeptide comprising d), wherein the EM of the first polypeptide and the EM of the second polypeptide are dimerized. 97. The activatable IL12 fusion protein or the activatable IL12 construct of claim 95, wherein e) further comprises a MM and a second cleavable moiety (CM2) such that it comprises a structural arrangement of: N´-MM-CM2-p40-p35-CM-EM-C´. 98. The activatable IL12 fusion protein or the activatable IL12 construct of claim 95, wherein f) further comprises a second cleavable moiety (CM2) such that it comprises a structural arrangement of: N´-p40-p35-CM-MM-CM2-EM-C´. 99. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 95-98, further comprising at least one of a first linking region (LR1) and a second linking region (LR2). 100. The activatable IL12 fusion protein or the activatable IL12 construct of claim 99, comprising: a) N´-p35-LR1-EM-LR2-CM-p40-C´; b) N´-p35-EM-LR1-CM-p40-C´; c) N´-p35-LR1-EM-CM-p40-C´; d) N´-p40-LR1-EM-LR2-CM-p35-C´; e) N´-p40-EM-LR1-CM-p35-C´; f) N´-p40-LR1-EM-CM-p35-C´; g) N´-p35-CM-LR1-EM-LR2-p40-C´; h) N´-p35-CM-EM-LR1-p40-C´; i) N´-p35-CM-LR1-EM-p40-C´; j) N´-p40-LR1-CM-EM-LR2-p35-C´; k) N´-p40-CM-EM-LR1-p35-C´; l) N´-p40-LR1-CM-EM-p35-C´; 334 CYTX-115-PCT 4862-0152WO1 m) N´-p40-p35-CM-LR1-EM-C´; n) N´-p40-p35-CM-LR1-MM-LR2-EM-C´; or o) a dimer of any combination of two polypeptides of one or two of a)-n). 101. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71-94 and 99-100, wherein the LR1, the LR2, or both the LR1 and the LR2 are each independently 7 to 45 amino acids amino acids in length. 102. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71-94 and 99-100, wherein the LR1 and the LR2 are each independently at least 7 amino acids amino acids in length. 103. The activatable IL12 fusion protein or the activatable IL12 construct of claim 102, wherein the LR1 and the LR2 are each independently 7 to 300 amino acids amino acids in length. 104. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71-94 and 99-100, wherein the LR1 and the LR2 are each independently 1 to 300 amino acids in length. 105. The activatable IL12 fusion protein or the activatable IL12 construct of claim 104, wherein the LR1 and the LR2 are each independently 1 to 60 amino acids in length. 106. The activatable IL12 fusion protein or the activatable IL12 construct of claim 105, wherein the LR1 and the LR2 are each independently 4 to 50 amino acids in length. 107. The activatable IL12 fusion protein or the activatable IL12 construct of claim 106, wherein the LR1 and the LR2 are each independently 4 to 43 amino acids in length. 108. The activatable IL12 fusion protein or the activatable IL12 construct of claim 107, wherein the LR1 and the LR2 are each independently 29 to 43 amino acids in length. 335 CYTX-115-PCT 4862-0152WO1 109. The activatable IL12 fusion protein or the activatable IL12 construct of claim 107, wherein the LR1 and the LR2 are each independently 17 to 21 amino acids in length. 110. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71-109, wherein the EM is selected from a polyalkylene glycol polymer, a hexa-hat GST (glutathione S-transferase) glutathione affinity, Calmodulin-binding peptide (CBP), Strep-tag, Cellulose Binding Domain, Maltose Binding Protein, S-Peptide Tag, Chitin Binding Tag, Immuno-reactive Epitopes, Epitope Tags, E2Tag, HA Epitope Tag, Myc Epitope, FLAG Epitope, AU1 and AU5 Epitopes, Glu-Glu Epitope, KT3 Epitope, IRS Epitope, Btag Epitope, Protein Kinase-C Epitope, VSV Epitope, a latency associated protein (LAP), or a serum albumin protein. 111. The activatable IL12 fusion protein or the activatable IL12 construct of claim 110, wherein the EM is human serum albumin (HSA). 112. The activatable IL12 fusion protein or the activatable IL12 construct of claim 111, wherein the EM is an albumin binding peptide comprising the amino acid sequence QRLMEDICLPRWGCLWEDDF (SEQ ID NO: 1424). 113. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71-109, wherein the EM is a dimerization domain (DD). 114. The activatable IL12 fusion protein or the activatable IL12 construct of claim 113, wherein the DD is an IgG Fc domain, optionally wherein the IgG Fc domain is a human IgG Fc domain. 115. The activatable IL12 fusion protein or the activatable IL12 construct of claim 114, wherein the Fc domain is covalently bound to a second Fc domain via at least one disulfide bond thereby forming a dimer. 116. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71-94 and 99-115, wherein at least one of the LR1 and the LR2 comprises a CM. 336 CYTX-115-PCT 4862-0152WO1 117. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71-116 wherein the CM is a substrate for a matrix metalloprotease (MMP) or a serine protease, or both. 118. The activatable IL12 fusion protein or the activatable IL12 construct of claim 117, wherein the MMP is MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, or MMP14. 119. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71-116, wherein the CM comprises an amino acid sequence of SEQ ID NO: 1388; and wherein the CM is a substrate for a protease. 120. The activatable IL12 fusion protein or the activatable IL12 construct of claim 119, wherein the CM comprises a sequence selected from: SEQ ID NOs: 1389,1394, 1399, 1404, 1409, 1414, or 1419. 121. The activatable IL12 fusion protein or the activatable IL12 construct of claim 119, wherein the CM comprises a sequence selected from: SEQ ID NOs: 1390-1423. 122. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 71-116, wherein the CM comprises SEQ ID NOs: 428, 246, 247, 1354, 805, 1278, or 144. 123. The activatable IL12 fusion protein or the activatable IL12 construct of claim 122, wherein the CM comprises SEQ ID NO: 428 or SEQ ID NO: 805. 124. The activatable IL12 fusion protein or the activatable IL12 construct of any one of claims 75-123, wherein the MM is less than 300 amino acids in length. 125. The activatable IL12 fusion protein or the activatable IL12 construct of claim 124, wherein the MM is about 400 to about 900 amino acids in length. 337
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