AU2008201889A1 - Growth hormone fusion protein - Google Patents

Description

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AUSTRALIA

FB RICE CO Patent and Trade Mark Attorneys Patents Act 1990 ASTERION LIMITED COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Growth hormone fusion protein The following statement is a full description of this invention including the best method of performing it known to us:- 00

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Modified Polypeptide This is a divisional of AU 2002366325, the entire contents of which are incorporated

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c herein by reference.

The invention relates to chimeric polypeptides wherein said polypeptides comprise a 00 00 modified binding domain of growth hormone linked to a receptor binding domain of 0growth hormone receptor; and tandems/oligomers of said modified growth hormone 00 binding domains.

C GH is a member of a large family of hormones involved in the regulation of mammalian growth and development. Human GH is a 22kDa polypeptide which is involved in a number of biological processes. For example, cell growth, lactation, the activation of macrophages and the regulation of energy metabolism. GH interacts sequentially with two membrane bound GHR's via two separate sites on GH referred as site 1 and site 2. Site 1 is a high affinity binding site and site 2 a low affinity site. A single GH molecule binds 1 GHR via site 1. A second GHR is then recruited via site 2 to form a GHR: GH: GHR complex. The complex is then internalised and activates a signal transduction cascade leading to changes in gene expression.

The extracellular domain of the GHR exists as two linked domains each of approximately 100 amino acids (SD-100), the C-terminal SD-100 domain being closest to the cell surface and the N-terminal SD-100 domain being furthest away.

It is a conformational change in these two domains that occurs on hormone binding with the formation of the trimeric complex GHR-GH-GHR.

Modified GH's are disclosed in US 5,849,535 which is incorporated by reference. The modification to GH is at both site 1 and site 2 binding sites. The modifications to site 1 produce a GH molecule which has a higher affinity for GHR compared to wild-type GH. These modified GH molecules act agonists. There is also disclosure of site 2 modifications which result in the creation of GH antagonists. Further examples of modifications to GH which alter the binding affinity of GH for site 1 are disclosed in US 5,854,026; US 6,004,931; US 6,022,711; US 6,057,292; and US 6,136,563 each of 0 2

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which are incorporated by reference. A summary of the modifications made to site 1 is provided in Table 1. Modifications to site 2 are also disclosed, in particular amino acid O residue G120 which when modified to either arginine, lysine, tryptophan, tyrosine,

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c phenylalanine, or glutamic acid creates a GH molecule with antagonistic properties.

In addition, the modified GH is coated in polyethylene glycol (PEG) by a process known as "pegylation" this has several beneficial effects. Firstly, the PEG coat 00 00 increases the effective molecular weight of GH from 22kD to approximately 0 The effect this has is to decrease glomerular filtration of GH thereby increasing the 00 half-life of GH in vivo which reduces the dose administered to produce the desired effect. In addition pegylation is thought to reduce both the immunogenicity and c toxicity of proteins which are treated in this way, see Abuchowski et al J Biol Chem., 252,3578-3581, (1977).

However, a consequence of pegylation is to reduce the affinity of the modified GH molecule for GHR. This means that an increased dose is required to counter the reduced affinity. This is undesirable since it counteracts the advantageous effect of pegylation with respect to increasing the half life of modified GH. It would be desirable to provide a modified GH molecule which does not require pegylation but has an increased half-life and also has the added benefits of reduced immunogenicity and lacks toxicity.

According to a first aspect of the invention there is provided a chimeric polypeptide comprising: i) at least one modified binding domain of growth hormone wherein said modification is the addition, deletion or substitution of at least one amino acid residue; and ii) a growth hormone binding domain of a growth hormone receptor.

The present invention also provides a chimeric polypeptide comprising: i) a first modified growth hormone receptor binding domain of growth hormone wherein said modification is the addition, deletion or substitution of at least one amino acid residue; and ii) a second modified growth hormone receptor binding domain of growth hormone wherein said modification is the addition deletion or substitution of at least one amino acid residue, characterized in that said binding domains are fused in tandem and the modification is to site 2 in at least one binding domain of growth hormone and wherein said polypeptide is an antagonist.

00 0 In a preferred embodiment of the invention said polypeptide is modified in the site 1 CN binding domain of growth hormone.

SIn a further preferred embodiment of the invention said polypeptide is modified in the site 2 binding domain of growth hormone.

00 00 In a yet further preferred embodiment of the invention said polypeptide is modified at both site 1 and site 2 of growth hormone.

00 As previously described, site 1 mutations are known in the art which increase the affinity of growth hormone for its binding domain on growth hormone receptor.

Such modified growth. hormone acts as an agonist. If a site 1 modification is combined with a site 2 modification wherein the latter modification results in an inactive or partially active site 2 binding site then such a molecule is an antagonist.

A modification just to site 2 which exploits a wild-type site 1 binding site also creates an antagonist.

In a further preferred embodiment of the invention there is provided a polypeptide comprising a site 1 binding domain which has been modified by amino acid substitution wherein said modification is selected -from the group consisting of: histidine 18 with alanine or aspartic acid; and/or histidine 21 with asparagine; and/or glutamine 22 with alanine; and/or phenylalanine 25 with alanine; and/or aspartic acid 26 with alanine; and/or glutamine 29 with alanine; and/or glutamic acid 167 with alanine; and/or aspartic acid 171 with serine; and/or lysine 172 with serine or alanine; and/or isoleucine 179 with tyrosine, of the sequence represented in Figure 13 Preferably said modification to increase the affinity of site 1 for its binding domain in GHR consists of the amino acid substitutions: histidine 18 aspartic acid; histidine 21 asparagine; arginine 167 asparagine; aspartic acid 171 arginine; glutamic acid 174 serine; and isoleucine 179 threonine; as represented by the GH amino acid sequence in Figure 13.

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SIn a further preferred embodiment of the invention said modification to increase the affinity of site 1 for its binding domain in GHR consists of the amino acid substitutions: histidine 18 alanine; glutamine 22 alanine; phenylalanine 25 alanine; aspartic acid 26 alanine; glutamine 29 alanine; glutamic acid 65 alanine; lysine 168 Salanine; and glutamic acid 174 alanine; as represented by the GH amino acid 00 Ssequence in Figure 13.

00 0In a further preferred embodiment of the invention said site 2 modification is to C 10 amino acid residue 120 of the sequence presented in Figure 13. Preferably said site 2 modification is combined with site 1 modifications as herein disclosed.

Alternatively, GH is modified only at amino acid residue glycine 120.

In a preferred embodiment of the invention said site 2 modification is a substitution of glycine for an amino acid selected from the group consisting of: arginine; alanine; lysine; tryptophan; tyrosine; phenylalanine; and glutamic acid. Preferably said substitution is glycine 120 for arginine or lysine or alanine.

In a further preferred embodiment of the invention the growth hormone binding domain of GHR js the extracellular domain of GHR. More preferably the binding domain is the C-terminal SD-100 domain of GH.

Alternatively said binding domain is the full length GHR.

In a preferred embodiment of the invention said chimeric polypeptide is a fusion protein wherein the modified GH is an inframe translational fusion with GHR, or part thereof. Preferaby, said fusion polypeptide comprises modified GH and the Cterminal SD-100 domain of GHR.

00 In an alternative further preferred embodiment of the invention, the modified binding CN domain of GH is linked by a linker to the GH binding domain of GHR. The linker Smay be flexible.

The linker could be at any residue within the extracellular domain of the receptor which would allow the modified GH to flexibly bind with the free receptor at the cell 00 surface. Preferably the linkage is made between a residue close to the C-terminus of the modified GH molecule and a residue close to the N-terminus of GHR. More 00 preferably the linkage is made between a residue close to the C-terminus of modified GH molecule and a residue close to the N-terminal of the N-terminal of the Cterminal SD-100. More preferably the linkage is made at any of residues 126-128 of the N-terminus of the C-terminal SD-100 of the GHR. In one embodiment of the invention, the linkage is made at residue 127 of the N-terminus of the C-terminal SD- 100. Preferably the linker is a peptide.

The crystal structure of the GHR:GH:GHR complex reveals that the distance between the C-terminus of GH (residue 191) and N-terminus of the C-terminus SD- 100 (residue 126-128) is 10A. This provides invaluable information with respect to linker design.

Preferably the linker is a polypeptide which comprises 5 to 30 amino acid residues.

More preferably the linker comprises 10 to 20 amino acid residues. More preferably still the linker comprises at least one copy of the peptide: Gly Gly Gly Gly Ser (hereinafter referred to as "Gly4Ser").

In one embodiment of the invention the linker is 10 amino acids in length and comprises two copies of the Gly4Ser linker. In an alternative embodiment of the invention, the linker is 15 amino acids in length and comprises three copies of the Gly4Ser linker. In yet an alternative embodiment, the linker is 20 amino acids in length and comprises four copies of the Gly4Ser linker.

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SIn a preferred embodiment of the invention said polypeptide is derived from human GH and human GHR.

According to a further aspect of the invention there is provided a nucleic acid Smolecule which encodes a polypeptide according to the invention selected from the 00 0 group consisting of: oO i) a nucleic acid molecule as represented by the nucleic acid sequence in Figure C 10 13; and ii) a nucleic acid molecule which hybridises to the nucleic acid sequence in Nucleic acid molecules which encode a modified growth hormone according to the invention can typically be synthesized by molecular techniques known in the art and include recombinant methods as well as the synthesis of nucleic acid molecules using oligonucleotide synthesizers.

In a preferred embodiment of the invention said nucleic acid molecule hybridises under stringent hybridisation.

The term "stringent hybridisation conditions" as used herein refers to parameters with which the art is familiar. Nucleic acid hybridization parameters may be found in references which compile such methods, e.g. Molecular Cloning: A Laboratory Manual, J. Sambrook, et al., eds., Second Edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, 1989, or Current Protocols in Molecular Biology, F.M. Ausubel, et al., eds., John Wiley Sons, Inc., New York. More specifically, stringent conditions, as used herein, refers, for example, to hybridization at 65°C in hybridization buffer (3.5 x SSC, 0.02% Ficoll, 0.02% polyvinyl pyrrolidone, 0.02% Bovine Serum Albumin, 2.5mM NaH 2

PO

4 (pH7), 0.5% SDS, ;0 2mM EDTA). SSC is 0.15M sodium chloride/0.015M sodium citrate, pH7; SDS is sodium dodecyl sulphate; and EDTA is ethylenediaminetetracetic acid. After 00 O hybridization, the membrane upon which the DNA is transferred is washed at 2 x C1 SSC at room temperature and then at 0.1 0.5 X SSC/0.1 x SDS at temperatures up to 68 0

C.

According to a further aspect of the invention there is provided a vector comprising the nucleic acid molecule according to the invention.

00 00 In a preferred embodiment of the invention said vector is an expression vector 00 adapted for recombinant gene expression.

Typically said adaptation includes, by example and not by way of limitation, the provision of transcription control sequences (promoter sequences) which mediate cell/tissue specific expression. These promoter sequences may be cell/tissue specific, inducible or constitutive.

Promoter is an art-recognised term and, for the sake of clarity, includes the following features which are provided by example only, and not by way of limitation. Enhancer elements are cis acting nucleic acid sequences often found 5' to the transcription initiation site of a gene (enhancers can also be found 3' to a gene sequence or even located in introiic sequences and is therefore position independent). Enhancers function to increase the rate of transcription of the gene to which the enhancer is linked. Enhancer activity is responsive to trans acting transcription factor which have been shown to bind specifically to enhancer elements. The binding/activity of transcription factors (please see Eukaryotic Transcription Factors, by David S Latchman, Academic Press Ltd, San Diego) is responsive to a number of environmental cues which include, by example and not by way of limitation, intermediary metabolites and/or environmental effectors.

Promoter elements also include so called TATA box and RNA polymerase initiation selection (RIS) sequences which function to select a site of transcription initiation.

00 These sequences also bind polypeptides which function, inter alia, to facilitate Stranscription initiation selection by RNA polymerase.

O Adaptations also include the provision of selectable markers and autonomous replication sequences which both facilitate the maintenance of said vector in either 0the eukaryotic cell or prokaryotic host. Vectors which are maintained autonomously 00 00 are referred to as episomal vectors. Episomal vectors are desirable since these Smolecules can incorporate large DNA fragments (30-50kb DNA). Episomal vectors Sof this type are described in W098/07876 which is incorporated by reference.

Adaptations which facilitate the expression of vector encoded genes include the provision of transcription termination/polyadenylation sequences. This also includes the provision of internal ribosome entry sites (IRES) which function to maximise expression of vector encoded genes arranged in bicistronic or multi-cistronic expression cassettes.

These adaptations are well known in the art. There is a significant amount of published literature with respect to expression vector construction and recombinant DNA techniques in general. Please see, Sambrook et al (1989) Molecular Cloning: A Laboratory Manual, Cold Spring Harbour Laboratory, Cold Spring Harbour, NY and references therein; Marston, F (1987) DNA Cloning Techniques: A Practical Approach Vol EI TRL Press, Oxford UK; DNA Cloning: F M Ausubel et al, Current Protocols in Molecular Biology, John Wiley Sons, Inc.(1994).

According to a further aspect of the invention there is provided the use of the polypeptide according to the invention as a pharmaceutical. In a preferred embodiment of the invention said polypeptide is for use in the manufacture of a medicament for the treatment of a condition selected from the group consisting of: gigantism, acromegaly; cancer Wilm's tumour, osteogenic sarcoma, breast, colon, prostate, thyroid); diabetic retinopathy; diabetic nephropathy and other complications of diabetes and GH excess.

00 C The polypeptides and compositions of the invention can be administered by any Sconventional route, including injection or by gradual infusion over time. The administration may, for example, be oral, intravenous, intraperitoneal, intramuscular, intracavity, intraocular, subcutaneous, or transdermal. The pharmaceutical compositions may conveniently be presented in unit dosage form and may be 00 00 prepared by any of the methods well-known in the art of pharmacy.

0 00 When administered, the pharmaceutical preparations of the invention are applied in O 10 pharmaceutically-acceptable amounts and in pharmaceutically-acceptable compositions. The term "pharmaceutically acceptable" means a non-toxic material that does not interfere with the effectiveness of the biological activity of the active ingredients. Such preparations may routinely contain salts, buffering agents, preservatives, compatible carriers, and optionally other therapeutic agents.

The compositions may be combined, if desired, with a pharmaceutically-acceptable carrier. The term "pharmaceutically-acceptable carrier" means one or more compatible solid or liquid fillers, diluents or encapsulating substances which are suitable for administration into a human. The term "carrier" denotes an organic or inorganic ingredient, natural or synthetic, with which the active ingredient is combined to facilitate the application. The pharmaceutical compositions may contain suitable buffering agents, including: acetic acid in a salt; citric acid in a salt; boric acid in a salt; and phosphoric acid in a salt. The pharmaceutical compositions also may contain, optionally, suitable preservatives, such as: benzalkonium chloride; chlorobutanol; parabens and thimerosal.

According to a yet further aspect of the invention there is provided a cell transformed or transfected with the nucleic acid or vector according to the invention.

In a preferred embodiment of the invention said cell is a eukaryotic cell. Preferably said cell is selected from the group consisting of: a slime mould Dictyostelium 00 O spp) a yeast cell Saccharomyces cerevisae; Pichia spp); a mammalian cell S(e.g.Chinese Hamster Ovary); a plant cell; an insect cell (e.g.Spodoptera spp).

SIn an alternative preferred embodiment said cell is a prokaryotic cell, preferably Escherchia coli or Bacillus spp.

00 oO 00 According to a further aspect of the invention there is provided a method to manufacture the polypeptide according to the invention comprising: 00 10 i) providing a cell according to the invention; ii) incubating said cell under conditions conducive to the production of the polypeptide according to the invention; and optionally iii) isolating the polypeptide from the cell or the cell culture medium.

In a preferred method of the invention said polypeptide is provided with a secretion signal to facilitate the purification of the polypeptide from said cell. More preferably still said polypeptide is provided with an affinity tag to facilitate the purification of the polypeptide from said cell or the cell culture medium.

According to a yet further aspect of the invention there is provided a method of treatment of a mammal, preferably a human, comprising administering to said mammal the polypeptide according to the invention.

According to a further aspect of the invention there is provided a chimeric 1 5 polypeptide comprising more than two modified growth hormone binding domains wherein said modification is the addition, deletion or substitution of at least one amino acid residue.

In a preferred embodiment of the invention there is provided a chimeric polypeptide 0 comprising a plurality of modified growth hormone binding domains.

00 0 In a further preferred embodiment of the invention there is provided a chimeric N polypeptide comprising at least two modified site 2 growth hormone binding domains.

C 5 In a further preferred embodiment of the invention there is provided a chimeric polypeptide comprising 3, 4, 5, 6, 7, 8, 9, 10 modified site 2 growth hormone binding 00 domains.

00 OO In a yet further preferred embodiment of the invention said chimeric polypeptide S 10 comprises more than two modified growth hormone binding domains linked together by a linker molecule. Preferably said linker molecule is as hereinbefore disclosed.

According to a yet further aspect of the invention said chimeric polypeptide comprising more than two modified growth hormone binding domains further comprises at least one growth hormone binding domain of a growth hormone receptor.

Preferably said chimeric polypeptide consists of two modified growth hormone binding domains and one growth hormone binding domain of a growth hormone receptor.

Preferably said chimeric polypeptide consists of at least two modified site 2 growth hormone binding domains.

Aspects and embodiments which relate to a chimeric polypeptide comprising growth a hormone binding domain linked to a receptor binding domain are applicable to chimeric polypeptides comprising more than or a plurality of growth hormone binding domains. For example, vectors comprisng nucleic acids encoding said chimeric polypeptides, pharmaceutical compositions comprising said polypeptides, cell-lines expressing said chimeric polypeptides, methods to' manufacture said 0 12 polypeptides and methods of treatment utilising said polypeptides are all within the a scope of the invention with respect to this species of chimeric polypeptide.

SThroughout this specification the word "comprise", or variations such as c "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

00 00 Any discussion of documents, acts, materials, devices, articles or the like which 0has been included in the present specification is solely for the purpose of providing a 00 context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the c field relevant to the present invention as it existed before the priority date of each claim of this application.

An embodiment of the invention will now be described by example only and with reference to the following table and figures: Table 1 represents a summary of the amino acid substitutions to site 1 and site 2 of human GH; Figure 1 Plasmid map of pHEAT.GH.G120R, which was generated by ligating the GH.G120R gene, synthesised by PCR, between the BamHI and NotI restriction sites. The selective marker on the plasmid is AmpR Figure 2 Plasmid map of pTrcHis-TOPO. 1A7, which was generated by ligating the GH.G120R gene between the BamHI and NotI sites in pTrcHis IAl. The linker is

(G

4

S)

4 and the selective marker on the plasmid is AmpR Figure 3 Plasmid map of pTrcHis-TOPO. 1B2, which was generated by ligating the GH.G120R gene between the BamHI and NotI sites in pTrcHis 1B1. The linker is

(G

4

S)

4 and the selective marker on the plasmid is AmpR Figure 4 Plasmid map of pTrcHis-TOPO. 1C3, which was generated by ligating the GH.G120R gene between the EcoRI and HinDIII sites in pTrcHis 1A7. The linker is (G 4

S)

4 and the selective marker on the plasmid is AmpR; Figure 5. Sequence of the GH.G120R gene, showing the start codon, 6xHis tag, relevant restriction sites, stop codons and the G120R mutation (CGC). The actual component is shown in CAPITALS, and the sequenced regions are shown in bold.

00 Figure 6. Sequence of the 1A7 gene, showing the start codon, 6xHis tag, relevant restriction sites, stop codons and the G120R mutation (CGC). The actual GH.G120R-

(G

4

S)

4 -GHR(b) component is shown in CAPITALS, and the sequenced regions are shown in bold; Figure 7. Sequence of the 1B2 gene, showing the start codon, 6xHis tag, relevant 00 restriction sites, stop codons and the G120R mutation (CGC). The actual GH.G120R-

(G

4

S)

4 -GHR(flec) component is shown in CAPITALS, and the sequenced regions are 00 shown in bold; Figure 8. Sequence of the 1C3 gene, showing the start codon, 6xHis tag, relevant restriction sites, stop codons and the G120R mutation (CGC). The actual GH.G120R-

(G

4

S)

4 -GH.G120R component is shown in CAPITALS, and the sequenced regions are shown in bold; Figure 9. Western blots using anti-human GH as the primary antibody of 15% SDS' PAGE gels for the expression studies of GH.G120R, 1A7, 1B2 and 1C3.

Expression was from the pTrcHis vector in E. coli XL1 Blue or E. coli SURE cells, these samples were taken 4 hours after induction with ImM (final concentration) IPTG. The blots show that GH.G120R and 1C3 produce single bands, while the samples of 1A7 and 1B2 contain cleavage products; Figure 10. Coomassie stained 15% SDS PAGE gels of purified GH.G120R, 1A7 and 1C3. Western blots of these samples using anti-human GH as the primary antibody are also shown. The coomassie stained gels show that the purified protein samples are >95% pure, however the western blots show that only GH.G120R and 1C3 produce single bands, while the sample of 1A7 contain cleavage products; Figure 11 Graphs showing the results of the GH bioassay fro GH.G120R, 1A7 and 1C3. Each graph shows a stardard curve, the assay with the construct alone at 00 different concentrations and the assay with the construct at different concentrations Swith 25ng/ml hGH. These show that none of the proteins have inherent agonistic activity, but all have antagonistic activity with the GH.G120R being the most active, 0 and 1A7 the least; Figure 12 is the amino acid sequence of unmodified GH; 00 00 Figure 13 is the nucleic acid sequence of unmodified GH.

00 Materials and Methods The methods to generate modified GH at site 1 and/or site 2 are disclosed in US 849, 535; US 5,854,026; US 6,004,931; US6,022,711; US6,057,292; and US6136563 each of which is incorporated by reference.

DNA constructs GENERATION OF SITE 2 MUTATED GH ANTAGONIST (GHa) The cDNA for human GH (Fig 1) has been PCR amplified from human pituitary tissue and cloned into the vector pTrcHis-Topo (pTrcHis-TOPO-GHstop). The GHR extracellular domain was amplified from human liver cDNA using PCR.

Growth Hormone Antagonist (G120R) Constructs G120R Mutation of Growth Hormone The growth hormone (GH) gene was mutated using the phagemid ssDNA mutation method. The GH gene was first sub-cloned from pTrcHisGH into pT7T318 between BamHI and Hindl sites, to produce pT7T318-GH. This plasmid was then transformed into E. coli CJ236 and single stranded ssDNA produced.

00 The ssDNA pT7T318-GH was then mutated by changing the codon for Glyl2O from ci GGC to CGC, the primer GI-L(Gl 2OR)For was used (Table 1).

The dsDNA pT7T3 18-GH.Gl2OR produced after the mutation process was then used to sub-clone the GH.G120R into a pHEAT vector, this gave pKEAT.GH.G120R (Fig.l1).

00 00 Generation of GH.G12OR Constructs 00 10 X lA7 [GH.G120R-QG 4 4 -GH{R(b)1 GHa linked to b domain of GHR.

The GH.Gl20R gene was excised from pHEAT.GH.LG120R (Fig. 1) using the restriction sites BamnHI and NotI. The gene was then ligated in place of the GH gene in pTrcHisX1Al [GH-(G 4

S)

4 -GRR(b)] (Fig. The resulting plasmid was transformed into Escherichia coli XLl Blue and plated, on LB glucose, 50 tgml ampicillin, 12.5pLg/ml tetracycline) agar plates.

~1B2 rGH-G 1 2R-(G 4 4 -GHYflecI GHa linked to fall length extracellular domain of the GHR.

The strategy used to generate the 'X1A7 gene was repeated, however the recipient vector was pTrcHisX1Bl [GH-(G 4

S)

4 -G}TRflec] (Fig. The resulting p lasmid was transformed into E. coli XL1 Blue and plated on LB glucose, ampicillin, 12.5 pig/mI tetracycline) agar plates.

XIC3 rGH-G120R-(GSn 4 4-GH.G12OR1 GHa tandem.

A PCR reaction was performed on pTrcHisGH using the primers DiGHEcoFi and DiOJIHinRi (Table The PCR product was then d igested with EcoRll and HindJI[, this was then ligated in place of the GJ{R(b) domain in pTrcHisXlA1 [GH-

(G

4

S)

4 -GHR(b)] (Fig. The resulting plasmid was transformed into the recombinant deficient coli SURE and plated on LB glucose, 50 ig/ml ampicillin, 12.5gg/ml tetracycline, 50jig/ml kanamycin) agar plates.

Sepjuencin2 Results 00 SPlasmids containing the construct genes were sequenced. The sequences of the genes and the regions sequenced for GH.G120R, X1A7, X1B2 and X1C3 are shown in Figs.

5-8, respectively.

Expression Studies 00 00 Single colonies were used to inoculate 3ml LB glucose, 50g/ml ampicillin, 12.5pg/ml tetracycline) broth for E. coli XL1 Blue cells and LB glucose, 00 0 10 50pig/ml ampicillin, 12.5gg/ml tetracycline, 50p.g/ml kanamycin) broth for E. coli CN SURE cells. These were grown, shaking, overnight at 37 0

C.

4mls of 4YT media, containing the appropriate antibiotics, were then inoculated with 200gl of the overnight LB culture. These were grown for 3 hours, .ml samples were then taken (To samples).

The 4YT cultures were then induced with IPTG to a final concentration of ImM and then further incubated for another 4 hours (T 4 samples).

The To and T 4 samples were processed immediately after they had been taken. They were first centrifuged to pellet the cells, the supematant was then discarded and the pellet processed for running on a SDS PAGE gel. Protein was visualised on these PAGE gels by either Coomassie staining or by western blot using an anti-GH primary antibody to probe for the construct.

In all cases the Coomassie stained PAGE gels do not show over-expression of the construct. However, the constructs are observed on the western blots (Fig. These show that in all cases protein of the correct size is expressed.

Purification In general protein was purified from 4 x 250ml cultures grown in 4YT, containing the appropriate antibiotics, and induced for 4-5 hours with IPTG to a final 0 concentration of 1mM. The cells were harvested by centrifugation and lysed by C, treatment with lysozyme and sodium deoxycholate followed by sonication.

The lysed cells were centrifuged to remove cell debris and the superatant initially 5 purified using Invitrogen ProBond Resin (Ni-column). Protein was eluted using imidazole.

00 00 The protein sample was further purified by diluting the eluant from the Ni-column times in a suitable buffer and then passing it through a MonoQ ion-exchange column.

Protein was eluted using a salt gradient of 0-1M NaCI over 20ml at a rate of c, 0.5ml/min; 0.5ml fractions were collected. The fractions were then analysed for the presence of the construct, and the fractions containing the-construct pooled.

The purified protein was analysed by SDS PAGE (Coomassie staining and western blot) (Fig. 10) and assayed to measure its concentration. The protein was then submitted for the bioassay.

In the cases of 1A7 and X1B2, which showed cleaved products by western blot, the constructs were submitted to the Rapid Translation System (RTS) for in vitro transcription. Previous, studies on X1A1 and XIB1 have shown that cleavage was greatly reduced using the RTS system in conjunction with protease inhibitors and chaperones for expression.

Bioassay The purified constructs were submitted to the Asterion standard GH bioassay.

Prepared 293 Hi, which stably express growth hormone receptor, were stimulated with the construct using a range of doses. A second duplicate plate was also prepared, but 25ng/ml GH was added 30min. after adding the construct to observe the antagonistic capability of the construct.

All the GH.G120R constructs had antagonistic activities (Fig. 11).

00

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SScreening of Antagonist Activity O An established bioassay is used to screen for antagonist activity A permanent cell line expressing the full length GHR is transiently transfected with a luciferase reporter that binds activated Stat5 Twenty-four hours later the cells are oO stimulated with GH for. 6 hours with or without antagonist. The cells are then lysed and luciferase activity measured 00 0 10 Testing metabolic clearance rate in vivo Sprague-Dawley rats are anaesthetised and cannulae implanted in femoral and jugular veins. Two days later GH chimera or tandem is administered by intravenous or subcutaneous injection. Blood samples are collected via the femoral cannula and chimera and tandem or oligomer protein levels measured by radio-immunoassay.

Pharmacokinetic parameters are estimated using available computer programs fitting hormone concentration against time.

Table 1 represents a summary of amino acid substitutions made to site 1 of GH.

Modifications to site 2 include the substitution of G120 for any of arginine; alanine; lysine; tryptophan; tyrosine; phenylalanine; or glutamic acid.

H18 H2 Q22 F25 D26 Q29 E65 R167 K168 D171 K172 E174 1179 1 D N N A S R S T A A A A A A A A_ A A A A A A

A

D A A A A A A S A A A 'A A A A S D A A A A A A A A A A A A A A A D N N A S R S T A A A A A A A A

Claims (25)

1. A chimeric polypeptide comprising: i) a first modified growth hormone receptor binding domain of growth hormone wherein said modification is the addition, deletion or substitution of at least one amino acid residue; and 00 00 ii) a second modified growth hormone receptor binding domain of growth Shormone 00 wherein said modification is the addition deletion or substitution of at least one amino acid residue, characterized in that said binding domains are fused in tandem and C I the modification is to site 2 in at least one binding domain of growth hormone and wherein said polypeptide is an antagonist.

2. A polypeptide according to claim 1 wherein said first and second binding domains are also modified in site 1 of growth hormone.

3. A polypeptide according to claim 1 wherein said first and second binding domains are modified in site 2 of growth hormone.

4. A polypeptide according to claim 1 wherein said modification is to binding domains of both site 1 and site 2 of growth hormone. A polypeptide according to claim 1 wherein said modification is selected from the group consisting of: histidine 18 with alanine or aspartic acid; and/or histidine 21 with asparagine; and/or glutamine 22 with alanine; and/or phenylalanine 25 with alanine; and/or aspartic acid 26 with alanine; and/or glutamine 29 with alanine; and/or glutamic acid 167 with alanine; and/or aspartic acid 171 with serine; and/or lysine 172 with serine or alanine; and/or isoleucine 179 with tyrosine, as represented by the GH amino acid sequence in Figure 12.

6. A polypeptide according to claim 1 wherein said modification consists of the amino acid substitutions: histidine 18 aspartic acid; histidine 21 asparagine; arginine 167 asparagine; aspartic acid 171 arginine; glutamic acid 174 serine; and isoleucine 179 threonine; as represented by the GH amino acid sequence in Figure 12. 00

7. A polypeptide according to claim 1 wherein said modification consists of the Samino acid substitutions: histidine 18 alanine; glutamine 22 alanine; phenylalanine alanine; aspartic acid 26 alanine; glutamine 29 alanine; glutamic acid 65 alanine; lysine c 168 alanine; and glutamic acid 174 alanine; as represented by the GH amino acid sequence in Figure 12. 00 00 8. A polypeptide according to any of claims 1 to 3 wherein said site 2 modification 0is to amino acid residue glycine 120 of the amino acid sequence presented in Figure 00

12. N 9. A polypeptide according to claim 8 wherein said site 2 modification is a substitution of glycine for an amino acid selected from the group consisting of: arginine; alanine; lysine; tryptophan; tyrosine; phenylalanine; and glutamic acid. 10. A polypeptide according to claim 9 wherein said site 2 substitution is glycine 120 for arginine or lysine or alanine. 11. A polypeptide according to any of claims 1 to 10 wherein the first modified binding domain of growth hormone is linked by a linker to the second growth hormone binding domain. 12. A polypeptide according to claim 11 wherein the linker is a polypeptide which comprises 5 to 30 amino acid residues.

13. A polypeptide according to claim 12 wherein the linker comprises 10 to 20 amino acid residues.

14. A polypeptide according to claim 12 or 13 wherein the linker comprises at least one copy of the peptide Gly Gly Gly Gly Ser.

15. A nucleic acid molecule which encodes a polypeptide according to any of claims 1 to 14.

16. A vector comprising the nucleic acid molecule according to claim

17. A vector according to claim 16 wherein said vector is an expression vector adapted for recombinant expression. 00 21 O

18. A polypeptide according to any of claims 1 to 14 for use as a pharmaceutical.

19. Use of the polypeptide according to any of claims 1 to 14 for the manufacture of a medicament for the treatment of a condition selected from the group consisting of: giantism; acromegaly; cancer; Wilm's tumour, osteogenic sarcoma, breast, colon, Sprostate, thyroid; diabetic retinopathy; diabetic nephropathy, diabetic complications. 00 Use according to claim 19 wherein said condition is acromegaly. 00

21. A pharmaceutical composition comprising a polypeptide according to any of C N claims 1 to 14.

22. An isolated cell, wherein said cell is transformed or transfected with the nucleic acid or vector according to any of claims 15 to 17.

23. An isolated cell according to claim 22 wherein said cell is a eukaryotic cell selected from the group consisting of: a slime mould; a yeast cell; a mammalian cell; a plant cell; an insect cell.

24. A cell according to claim 22 wherein said cell is a prokaryotic cell. A method to manufacture a polypeptide according to any of claims 1-14 comprising: i) providing a cell according to any of claims 22 to 24; ii) incubating said cell under conditions conducive to the production of said polypeptide; and optionally iii) isolating the polypeptide from the cell or the cell culture medium.

26. A method according to claim 25 wherein said polypeptide is provided with a secretion signal to facilitate the purification of the polypeptide from said cell.

27. A method according to claim 25 or 26 wherein said polypeptide is provided with an affinity tag to facilitate the purification of the polypeptide from said cell or the cell culture medium. 00 22

28. A chimeric polypeptide according to claim 1 comprising a plurality of modified Sgrowth hormone binding domains. c

29. A polypeptide according to claim 28 wherein said polypeptide comprises 3, 4, 6, 7, 8, 9, or at least 10 site 2 modified growth hormone binding domains. 00 00 30. A polypeptide according to claim 29 wherein said polypeptide comprises 2 Smodified site 2 growth hormome binding domains. 00

31. A method to treat a disease or condition that would benefit from a polypeptide c N antagonist according to any of claims 1 to 14 or 28 to 30 comprising administering said polypeptide to human subject.

32. A method according to claim 31 wherein said disease or condition is selected from the group consisting of: gigantism; acromegaly; cancer; diabetic retinopathy; diabetic nephropathy; diabetic complications and any disease of GH excess.

33. A method according to claim 32 wherein said disease is acromegaly.