HK1169961B - Immunomodulatory polypeptides derived from il-2 and their use thereof in the therapeutic of cancer and chronic infections - Google Patents

Description

Immunomodulatory polypeptides derived from IL-2 and their use in the treatment of cancer and chronic infections

Technical Field

The present invention relates to the field of biotechnology, in particular immunology. The present invention relates to a technical solution with therapeutic application for human health. The invention particularly relates to the therapeutic modulation of the immune system using analogues of natural molecules.

Background

Interleukin 2(IL-2) is the first growth factor described for T cells. Since its discovery, it has shown a strong ability to promote T cell proliferation and survival in vitro (Smith, KA (1988) science.240,1169-76) and to enhance T cell immune responses in vivo in the case of viral infection (Blattman, JN, et al (2003) Nat Med 9,540-7) or in the case of vaccines (fisherman, m., et al (2008) J immunology.31, 72-80, Kudo-Saito, c., et al (2007) Cancer Immunol Immuno.56, 1897-910; Lin, CT, et al (2007) Immunol Lett.114, 86-93). However, recently, a number of experimental data have questioned this classical role of IL-2 as a promoter of the T immune response (Almeida, A.R., et al (2002) J Immunol.169,4850-60; de la Rosa, M., et al (2004) Eur J Immunol.34,2480-8; Malek, T.R., et al (2004) Nat RevImmunol.4,665-74), these data suggest that the cytokine is a self-stabilizing growth factor for naturally regulated T cells TCD4+ CD25+ FoxP3+ (Treg).

Interleukin-2 is a major participant in the mechanism by which regulatory T cells suppress the activity and expansion of other effector cells, such as CD4 helper T cells, CD8 cytotoxic T cells, and NK cells. In particular, it has recently been proposed that regulatory T cells inhibit other T cells, inducing a local decrease in IL-2 levels (Pandiyan, p., et al (2007) Nat immunol.8, 1353-62). This inhibitory effect is based on: a) they directly inhibit the production of IL-2 by effector T cells they inhibit (Almeida, A.R., et al. (2002) J Immunol.169,485060; Takahashi, T., et al. (1998) Int Immunol.10,1969-80; Thornton, A.M., et al. (1998) J Exp Med.188,287-96; Wolf, M., et al. (2001) Eur JImmunol.31,1637-45); b) the ability to rapidly and efficiently deplete IL-2 in their microenvironment (Pandiyan, P., 2007) Nat Immunol.8,1353-62); and c) the ability to overexpress IL-2. alpha. chain receptors (Kuniyasu, Y., et al. (2000) Int. 12, et al.5-1145), which makes them more effective at low IL-2 concentrations.

In conclusion, IL-2 is a very pleiotropic cytokine which has a very important significance for the biological activity of different cell populations. This property makes IL-2 an important node in the regulation of immune responses, making it an interesting and complex target for immunomodulatory therapies. In particular, the pleiotropic nature of the action of this cytokine makes it of great importance for the design of therapeutic strategies that modulate the activity of this cytokine in a selective/preferential manner among different cell populations.

IL-2 has been used for cancer therapy for several years. In particular, it is approved in several countries for the treatment of melanoma and renal cell carcinoma at high doses. However, the direct use of IL-2 in patients is severely limited due to its toxic effects. Only 20% of the eligible patients receive further treatment and only 17% show the associated objective response. One possible explanation for this significant failure in the clinical phase is: treatment with native IL-2 also stimulates a population of regulatory T cells that hampers the immune stimulation sought with it (Ahmadzadeh, m., et al (2006) blood.107, 2409-14).

Several strategies have been developed to mitigate the toxic effects of IL-2 treatment. Some of these strategies are based on the use of mutants of IL-2 designed to enhance the signaling capacity of this molecule, mainly through high affinity receptors (alpha, beta and gamma chains), but not through medium affinity receptors (beta and gamma chains). The basic idea is: signal transduction on T cells is preferentially promoted over signal transduction in NK cells, which are thought to be the cells responsible for the toxic effects observed. The following inventions are in the same line of research: us patent 7,186,804, us patent 7,105,653, us patent 6,955,807, us patent No.5,229,109, us patent application 20050142106. It is important to note that: none of these inventions relates to IL-2 mutants with the ability to differentially modulate the activity of regulatory T cells. In addition, the mutants in these inventions are agonists of IL-2, not antagonists/inhibitors, such as those described in this application.

Other IL-2 mutants have been developed for the purpose of enhancing the pharmacological activity of IL-2. For example, in order to improve its folding or to extend its life in the blood. Among these, the following invention relates to this research route: U.S. Pat. No. 4,959,314, U.S. Pat. No.5,116,943, U.S. Pat. No. 4,853,332. Likewise, none of these mutants showed the ability to differentially modulate the activity of regulatory T cells.

Other prior inventions relate to inhibitors of IL-2 activity, primarily for the treatment of autoimmune diseases or for the prevention of organ transplant rejection. Among them are the following inventions: us patent 5,876,717, us patent 5,635,597, us patent 6,906,170, us patent 6,168,785.

Finally, it should be mentioned that there are many proposals for therapeutic agents in the literature (Kreitman, R.J. (2009) Curr Pharm Des.15,2652-64; Litzinger, M.T., Fernando, R., Curiel, T.J., Grosenbach, D.W., Schlom, J.and Palena, C. (2007) blood.110,3192-201; Morse, M.A., Hobeika, A.C., Osada, T., Serra, D., Niedzwiecki, D.Lyerly, H.K. and Clay, T.M. (2008) blood.112,610-8; Tawara, I., Shimizu, J.K., Saguchi, Saita, Fukia.112, T.833, 833-8; Izoda, C., Alzhe, Alzhen, Vuil, S.19, Calif, S.19, Calif. A., Alzhen, S.19, Calif. A., T.19, Calif. A.A.19, and S.19, Calif. A.A, and S. A. A, and S. 19, and S. A. 5, and S.5, Calif. cells, which regulate their activity in vivo. These therapeutic agents have been tested in animal models, even in patients, to perform direct cancer therapy or to enhance the effect of vaccines. There are also reports suggesting that the activity of IL-2 is modulated, in particular to promote more effective immune responses by monoclonal antibodies (Boyman, o., Kovar, M., Rubinstein, m.p., Surh, c.d. and Sprent, J. (2006) science.311,1924-1927; Boyman, o., et al. (2006) Expert OpinBiol ther.6,1323-31; kamima, d., et al (2006) J immunol.177,306-14; Murakami, M., Sakamoto, a., Bender, J. kappa.j., J. kappa.j., j.andmarrack, P. (2002) Proc Natl Acad. usa.99, 32-887; toma, J., mmalova, h., chrvan, t., rivava, b.49J. (2009), Kovar. 04), or more effective immune responses. However, to our knowledge, no mutants of such IL-2 have been reported in the literature: supporting their potential for selectively or preferentially modulating the activity of regulatory T cells. In particular, IL-2 muteins are: capable of selectively/preferentially antagonizing the activity of IL-2 on regulatory T cells, thereby affecting its function and facilitating therapeutic enhancement of the immune response.

Disclosure of Invention

The invention is based on the following scientific findings: mutant variants of IL-2 are capable of producing preferential inhibition of regulatory T cells. The inventor discovers for the first time that: in vitro experiments, mutants of IL-2 were able to substantially inhibit the activity of regulatory T cells (T CD4+ CD25+ FoxP3+) with little effect on the activation and/or proliferation of other lymphocytes with effector functions. This discovery provides a novel strategy for immunomodulation of regulatory T cells in these cell-associated diseases, such as cancer or chronic infection.

The present invention relates to polypeptides sharing a primary sequence with human IL-2, but wherein several amino acids are mutated to eliminate or substantially reduce their signaling through different forms of the IL-2 receptor.

These mutant variants of IL-2 retain the ability to bind to one or more components of the IL-2 receptor and have preferential inhibitory activity against a population of regulatory T cells, where they negatively modulate their function. Several specific IL-2 mutant variants are provided that have preferential inhibitory properties for regulatory T cells. The invention also includes therapeutic applications of these mutants: alone or in combination with a vaccine for the treatment of diseases in which the activity of regulatory T cells (tregs) is associated, such as cancer or chronic infections.

The present invention proposes a novel strategy for modulating the activity of regulatory T cells in diseases in which the protective immune response induced naturally or by vaccines is reduced by inhibition of these cells. The advantages of this new therapeutic strategy are manifold over other proposed advantages of modulating Treg activity, such as:

● IL-2 mutant is essentially self protein (except some mutations). This fact reduces the risk of unexpected toxicity (which is common in small inhibitor-based strategies), or the risk of generating an immune response against the injected drug (which would occur in strategies such as Ontak, where IL-2 is coupled to a foreign and toxic molecule, such as diphtheria toxin).

● these mutant variants of IL-2 retain binding affinity for the receptor for IL-2, at least an order of magnitude greater than that of native IL-2 (10 pM for high affinity receptors). This affinity is difficult to achieve with strategies using receptor inhibitors or ligands, using monoclonal antibodies or other drugs.

● the small size of these mutants (15kD) allows them to have high mobility and to penetrate easily into the tumor microenvironment. This is known to be complicated for larger molecules such as antibodies and the like.

Detailed Description

Obtaining IL-2 analog polypeptides

The present invention relates to polypeptides of 100 to 500 amino acids, preferably 140 amino acids in size, having an apparent molecular weight of at least 15 kD. These polypeptides retain a high level of sequence identity, over 90% identity, with native IL2, and comprise 2 to 6 mutations relative to native IL-2 in their sequence regions.

In these positions, the polypeptides are mutated by insertion of amino acid residues that differ from those at the same position of native IL-2. Residues that replace the original residues were chosen because they have very different physicochemical properties than the original amino acids: residues change from polar to non-polar, from charged to uncharged, from large to small, from acidic to basic, and so forth.

The polypeptides of the invention may also be referred to as intrinsic immunomodulatory polypeptides, analogs of IL-2 or muteins of IL-2, and the like. These polypeptides are designed based on the 3D structure of IL-2 (stored in the PDB database) and introduce mutations only at those positions of IL-2 corresponding to amino acids that are significantly exposed to the solvent, as identified by using a public domain bioinformatic program such as RASMOL, SwissPDBviewer, etc.

The polypeptides of the invention can be obtained in several ways, for example by protein synthesis. They may also be obtained by genetic engineering techniques, such as expressing them in inclusion bodies in bacteria such as E.coli. Point mutations at specific positions can also be obtained by site-directed mutagenesis techniques using the polymerase chain reaction.

Analog polypeptides for selection of IL-2 by their biological activity

Selecting a polypeptide of the invention in vitro or in vivo experiments that simultaneously has the following characteristics:

1) these mutant variants of IL-2 lose, or have a substantially reduced ability to signal, different forms of the IL-2 receptor. This property can be determined directly in an in vitro proliferation assay by using IL-2 dependent cell lines (e.g. CTLL2 or Kitt225), or using T lymphocytes or NK cells of murine and/or human origin. These mutants should have at least 1/100 stimulating activity of native IL-2 in these assays.

2) These mutants of IL-2 (muteins) retain the ability to bind to one or more molecular components of the IL-2 receptor. The binding capacity can be determined by: direct assay by ELISA against commercially available receptor chains, e.g. alpha and beta chains of the receptor; or indirectly on a population of cells that are positive for the recipient. In these assays, the recognition rate of the IL-2 mutein should be comparable to native IL-2.

3) Mutants of IL-2 have inhibitory activity on native IL-2 activity on lymphocytes, and are preferred for regulatory T cell populations (at least in T CD4+ CD25+ FoxP3+ cells). Muteins of IL-2 included in the present invention are capable of preferentially or selectively inhibiting the activity or expansion of regulatory T cells over a range of concentrations without affecting or only minimally affecting the activity and/or expansion of other lymphocytes having effector function (e.g., T helper cells, cytotoxic T cells, or NK cells). The preferential or selective inhibitory activity of these muteins can be demonstrated in several in vitro tests, in which the response of a mixture of effector and regulatory populations to stimuli in the presence of increasing amounts of the mutein is determined. At suitable concentration ranges, they are at least 3-fold more potent in inhibiting the growth or activity of regulatory T cells relative to their inhibition of the activity or expansion of effector populations used in the experiment, such as T helper cells, cytotoxic T cells or NK cells.

The present invention also includes several specific variants of IL-2 muteins (specific mutations are disclosed in table 1) that have been selected with the above-described characteristics. These muteins comprise a plurality of amino acid substitutions that significantly reduce their ability to stimulate murine and human lymphocytes. However, their ability to bind to the alpha and beta chains of the receptor remains intact, and they acquire the ability to inhibit (antagonize) the natural activity of IL-2. The most significant aspects of these muteins are: in cultures of lymphocytes containing regulatory T cells and other effector T cells, they showed significant ability to preferentially inhibit regulatory T cells (CD4+ CD25+ FoxP3+) over a range of concentrations.

Mutations	Name (R)
		Q22V,Q126A,I129D,S130G	M1
L18N,Q126Y,S130R	M2
		Q13Y,Q126Y,I129D,S130R	M3
L18N,Q22V,T123A,I129D,S130R	M4

Table 1: constructed mutants, referred to by the numbering of human IL2

The present invention also includes additional modifications of the IL-2 mutants described above, particularly those types disclosed in table 1. Either to increase their affinity for specific components of IL-2 without affecting or even enhancing their preferential inhibitory properties, or to improve their in vivo pharmacodynamics: prolonging life cycle or reducing its internalization by T cells. These additional mutations can be obtained by rational design using bioinformatic tools, or by using combinatorial molecular libraries of different nature (phage display libraries, gene expression libraries in yeast or bacteria).

Therapeutic uses of IL-2 analog polypeptides

The invention also includes: pharmaceutical compositions comprising as active ingredient IL-2 muteins and analogues thereof as described in the present invention, and their potential therapeutic use aimed at selectively modulating IL-2 activity on regulatory T cells. In particular, the invention claims the use of these muteins for promoting a naturally induced or vaccine-induced immune response in diseases in which regulatory T cells are particularly relevant, such as cancer or chronic infections.

For therapeutic use, the polypeptides of the invention should be administered to carriers of the disease, either independently or in combination with other polypeptides or other agents that promote or enhance their therapeutic effect. The route of administration may be any of the routes of administration described in the prior art for parenteral administration of a drug. Preferably, administration may be by intravenous, intramuscular, subcutaneous or intratumoral routes.

The polypeptides or fusion proteins described herein may also be administered as part of a pharmaceutical composition for the treatment of cancer and chronic infectious diseases.

To obtain the desired therapeutic effect, the polypeptides of the invention should be administered in a high dose sufficient to ensure a sufficient concentration at the lymph nodes or relevant peripheral sites of the disease in question. It should be at a sufficient concentration so that the mutein exhibits a preferential inhibitory effect on regulatory T cells. Therefore, the dosage must be adjusted according to the type of disease and the route of administration under study. For example, in the case of tumor therapy, the dose should be adjusted until the concentration of the mutant in the tumor and/or regional lymph nodes is sufficient to ensure a preferential inhibitory effect on regulatory T cells. The dosage range employed may be from tens of micrograms to several milligrams per dose.

The number of administrations should also be adjusted according to the biodistribution of the mutein under study. Generally, the effective concentration should be maintained for a period of 2 days to 30 consecutive days. Note, for example, if the mutant protein is coupled to a carrier protein, the frequency of administration will be adjusted accordingly. By "therapeutic effect" is meant the complete or partial alleviation of the symptoms of the disease. For cancer, a decrease in tumor volume or an extension from the time of recurrence would be considered an indicator of remission. Finally, it should be noted that the advantages of this new therapeutic strategy over other proposals to modulate Treg activity are manifold. For example:

● IL-2 mutant is essentially self protein (except some mutations). This fact reduces the risk of unexpected toxicity (which is common in small inhibitor-based strategies), or the risk of generating an immune response against the injected drug (which would occur in strategies such as Ontak, where IL-2 is coupled to a foreign and toxic molecule, such as diphtheria toxin).

● these mutant variants of IL-2 retain binding affinity for the receptor for IL-2, at least an order of magnitude greater than that of native IL-2 (10 pM for high affinity receptors). This affinity is difficult to achieve with strategies using receptor inhibitors or ligands, using monoclonal antibodies or other drugs.

● the small size of these mutants (15kD) allows them to have high mobility and to penetrate easily into the tumor microenvironment. This is known to be complicated for larger molecules such as antibodies and the like.

Examples

Example 1

Mutants were designed in silico by bioinformatics techniques using Wang, X, Rickert, M.and Garcia, K.C.in Structure of the quantitative complex of interplukin-2 with t salpha, beta, and gamma arecers.science, 2005.310(5751) as a basis for the quaternary Structure of the complex of human IL-2 coupled to a receptor as reported in p.1159-63, and an energy calculation algorithm for protein-ligand interactions in the public domain. It was initially predicted that different variants of the mutein would not affect the binding capacity to the alpha and beta chains of the receptor. These muteins were expressed in E.coli from a genetic construct of the pET28a vector, which included the 6 histidine-identifying sequences at the amino terminus. Purification of the mutein using the reverse phase (fig. 1) resulted in high purity (> 95%). The muteins obtained were selected according to their properties in vitro experiments. In the constructed muteins shown in table 1, a specific group of mutations having the property of preferentially inhibiting the activity of tregs is described.

Example 2

The selected muteins retain the ability to bind to the different components of the IL2 receptor, in particular the alpha and beta chains of the receptor. FIG. 2 shows: using ELISA assays, several of the mutants shown in table 1 maintained the ability to bind to the alpha chain (see fig. 2) and beta chain (fig. 2b) of the IL-2 human receptor substantially intact. FIG. 3 shows that the binding of these mutants to receptors on the cell surface is further confirmed (see FIG. 3a), and that this binding can be gradually replaced by the addition of native IL-2 (FIG. 3 b).

Example 3

The ability of the selected muteins to signal through the IL-2 receptor is significantly reduced. Figure 3 demonstrates this by determining their ability to stimulate the growth of the CTLL2 cell line from total splenic lymphocytes (figure 4a) or to stimulate NK cell differentiation from total splenic lymphocytes (figure 4 b). At high concentrations, these muteins inhibited the activity of native IL-2 on T lymphocytes (FIG. 5a) and NK cells (FIG. 5 b).

Example 4

The selected muteins preferentially inhibited the in vitro expansion of regulatory T cells (CD4+ CD25+ FoxP3 +). Figure 6 demonstrates this property of one of the mutants in table 1, in particular showing that the addition of moderate doses of this mutein substantially inhibited the proliferation of CD4+ FoxP3+ in lymphocyte cultures stimulated with anti-CD 3 antibody, in which there was a mixture of effector and regulatory T cells, without significantly affecting the expansion of the CD4+ FoxP 3-effector population.

Example 5

The selected mutein is preferentially captured by regulatory T cells in culture, such that its ability to affect effector T cells is reduced. These muteins inhibit IL-2-mediated signaling (stimulation) by purified, anti-CD 3 antibody-stimulated CD4+ CD25-FoxP 3-helper T cell populations produced endogenously. However, mutant-mediated inhibition of the T effector population was reduced after addition of increasing numbers of CD4+ CD25+ FoxP3+ regulatory T cells to these cultures (fig. 7). This effect is explained as: the muteins preferentially inhibit the activity of IL-2 on a population of regulatory T cells. The presence of even small numbers of regulatory T cells targets the activity of the mutant to these cells, thereby reducing the inhibitory activity of the mutant on the effector population.

Example 6

The selected muteins showed antitumor activity in a mouse model of transplanted tumors. Figure 8 shows a table 1 of a mutant protein of this property. Muteins were evaluated in a primary tumor model with melanoma MB16F10 cell line (subcutaneously implanted in the right flank). FIG. 8 shows: tumor volume in mice treated with the mutein was reduced relative to the control group treated with PBS. In addition, a control group treated with an anti-CD 25 monoclonal antibody (MAb) was included, which showed that this experimental system was perceptible for Treg cell depletion.

Drawings

FIG. 1 production and purification of mutants of human IL-2. a: western blot showing the expression of native IL-2 of some mutants and controls in E.coli strains transfected with the constructed gene constructs. b: an example of a typical purification profile obtained using reverse phase purification.

FIG. 2 identification of the alpha (a) and beta (b) chains of the IL-2 receptor by several mutants described in Table 1 was assessed by ELISA. Native IL-2 was used as a positive control. It can be seen that all the muteins tested retained recognition rates comparable to native IL-2.

FIG. 3 several of the muteins described in Table 1 were tested for their ability to bind to the IL-2 receptor on the surface of cells, in particular the murine CTLL2 cell line, by flow cytometry. Mutants on the cell surface and native IL-2 controls were detected using anti-6-His-PE antibodies that recognize histidine heads (included in the genetic construct of these molecules). a) The method comprises the following steps Bar chart: the level of detected direct binding is shown; b) the method comprises the following steps The reduction of the binding of the mutein to the cells, determined by the decrease in the mean fluorescence intensity detected, is caused by the addition of increasing concentrations of native IL-2(a variant of this molecule without a histidine head and without interfering with the staining).

FIG. 4 evaluation of the signal transduction potential of several muteins shown in Table 1. a) The method comprises the following steps The proliferation of the CTLL2 cell line was measured colorimetrically using MTT to assess the activity of the mutant proteins; b) the method comprises the following steps Muteins were also evaluated in a differentiation assay of NK1.1+ cells from total mouse splenocytes. In both cases, we compared the stimulatory capacity of the muteins produced in the exact same experimental system (same genetic construct, E.coli producer, purification system) with the native IL-2 control. Results similar to those shown in FIG. 3a were obtained using the Kitt225 cell line, in which the receptor system is human.

FIG. 5 evaluation of the ability of several muteins described in Table 1 to inhibit native IL-2 activity in vitro. a: inhibition of total ganglion lymphocyte proliferation stimulated with anti-CD 3 monoclonal antibody (clone 2C11, 10. mu.g/mL) by increasing concentrations of the mutein. b: inhibition of differentiation of NK1.1+ cells from total mouse splenocytes stimulated with 500IU/mL native IL-2 by adding increasing amounts of mutein in culture.

FIG. 6 evaluation of the ability of the muteins to preferentially inhibit CD4+ Foxp3+ lymphocytes. Mouse lymph node lymphocytes were stimulated with anti-CD 3 monoclonal antibody (clone 2C11, 10 μ g/mL) in vitro in the presence of the indicated amount of M1 mutein (as referred to in Table 1). After 72 hours of culture, the number of viable CD4+ Foxp3+ regulatory lymphocytes and CD4+ Foxp3 effector lymphocytes was determined by flow cytometry using reference beads. The graph in a shows the basic staining in flow cytometry to distinguish between regulatory and effector cell populations. The graph in b shows the level of inhibition of proliferation induced by the different amounts of mutein added. The inhibition was calculated based on the number of viable cells recovered in the absence of the mutein. As shown in b, there is such a medium concentration range of M1 mutant protein: inhibition of the CD4+ FoxP3+ regulatory population was significantly higher than inhibition of CD4+ FoxP 3-helper or effector T cells.

FIG. 7 evaluation of the ability of regulatory T cells to preferentially capture engineered IL-2 muteins (release inhibitory effects on effector T cells). Effector T-cells CD4+ CD25-FoxP3 "were purified using CFSE-labeled magnetic beads and placed in culture, some with and without mutein (M1 mutein, two different concentrations in the figure: 10. mu.g/mL and 5. mu.g/mL) and stimulated with anti-CD 3 antibody (clone 2C11, 10. mu.g/mL) and anti-CD 28 (clone 37.51, 10. mu.g/mL). To these cultures, different numbers of purified regulatory T cells (CD4+ CD25+ FoxP3+) were added. Fig. 6a shows: high levels of purity were achieved using magnetic bead isolation (92% tregs, 97% for effector T cells). Fig. 6b shows: proliferation levels of effector cells were determined by CFSE dilution for different numbers of regulatory cells in culture. It can be seen that in the absence of tregs, the presence of the mutein significantly affects the proliferation of effector cells (suppressive effect), but with the addition of tregs, the proliferation of effector T cells is restored, since tregs preferentially capture the mutein, releasing suppressive effect on effector cells.

FIG. 8 direct anti-tumor effect of IL-2 mutein was evaluated using a primary tumor model with melanoma MB16F10 tumor cell line. 12C 57BL6 mice were used, 3 groups of 4 mice each. All treatments were performed subcutaneously on days-5 to 0. Group 1 received 200. mu.LPBS, group 2 received 100. mu.g of anti-CD 25MAb, and group 3 received 200. mu. gIL-2 mutein. On day 0, all mice received 250000 cells at the right flank fossa. Tumor volumes were measured every 2 days until day 30. Data were analyzed using the ANOVA test and the multiple comparison Bonferroni test method. The IL-2 mutein and the anti-CD 25MAb caused a significant delay in tumor growth (p < 0.001).

Claims (10)

1. An immunomodulatory polypeptide derived from IL-2, which has introduced a point mutation relative to the sequence of native IL-2 and has the property of preferentially inhibiting the activity of IL-2 on regulatory T cells in vitro, wherein the polypeptide:

(i) the mutations Q22V, Q126A, S130G and I129D were introduced relative to the sequence of native IL-2;

(ii) the mutations L18N, Q126Y and S130R were introduced relative to the sequence of native IL-2; or

(iii) Mutations Q13Y, Q126Y, I129D and S130R were introduced relative to the sequence of native IL-2.

2. The polypeptide of claim 1 which selectively and preferentially inhibits the activity of IL-2 on CD4+ CD25+ FoxP3+ natural regulatory T cells.

3. The polypeptide of claim 1, characterized in that it preferentially inhibits the ability of regulatory T cells in vivo.

4. A fusion protein consisting of an immunomodulatory polypeptide of any one of claims 1-3 coupled to a carrier protein.

5. Fusion protein according to claim 4, characterized in that the carrier protein is albumin.

6. Fusion protein according to claim 4, characterized in that the carrier protein is the Fc-region of a human immunoglobulin.

7. Use of a polypeptide according to any one of claims 1 to 3 for the manufacture of a medicament for the treatment of chronic infectious diseases or cancer that can be treated by IL-2.

8. A pharmaceutical composition for treating cancer and chronic infectious diseases, comprising the polypeptide of any one of claims 1 to 3 as an active ingredient.

9. Use of a fusion protein according to any one of claims 4 to 6 for the preparation of a medicament for the treatment of chronic infectious diseases or cancer that IL-2 can treat.

10. A pharmaceutical composition for treating cancer and chronic infectious diseases, comprising the fusion protein of any one of claims 4 to 6 as an active ingredient.