Antibodies that specifically bind to the EphA2 receptor

1. An antibody or an epitope-binding fragment thereof that specifically binds to an EphA2 receptor comprising at least one heavy chain and at least one light chain, wherein said heavy chain comprises three sequential complementarity-determining regions comprising the amino acid sequences of SEQ ID NOS: 1, 2, and 3, and wherein said light chain comprises three sequential complementarity-determining regions comprising the amino acid sequences of SEQ ID NOS: 4, 5, and 6.

2. An antibody or an epitope-binding fragment thereof according to claim 1 , wherein said monoclonal antibody or epitope-binding fragment thereof is a humanized or resurfaced antibody or epitope-binding fragment thereof.

3. An antibody or an epitope-binding fragment thereof according to claim 1 , wherein said heavy chain comprises the amino acid sequence of SEQ ID NO: 12 and wherein said light chain comprises the amino acid sequence, of SEQ ID NO: 14.

4. A conjugate of an antibody or an epitope-binding fragment according to claim 3 , wherein said conjugate comprises a cytotoxic agent chosen between:

a) the maytansinoid of formula (XIII):

b) the maytansinoid of formula (XIV):

c) the maytansinoid of formula (XXIV):

d) the maytansinoid of formula (XXV):

e) the maytansinoid of formula (XXVI):

f) the maytansinoid of formula (XXVII):

5. A conjugate according to claim 4 , wherein said cytotoxic agent is covalently bound to the antibody.

6. A conjugate according to claim 5 , wherein the cytotoxic agent is the maytansinoid of formula (XIII).

7. A pharmaceutical composition containing an antibody or epitope-binding fragment thereof according to claim 3 , or a conjugate according to claim 6 , and a pharmaceutically acceptable carrier or excipient.

8. A conjugate according to claim 6 having an average DAR above 4, the DAR being measured with a UV spectrophotometer and determined by the following equation

DAR= C D /C A

With:

C D =[(ε A280 ×A 252 )−(ε A252 ×A 280 )]/[(ε D252 ×ε A280 )−(ε A252 ×ε D280 )]

C A =[A 280 −(C D ×ε D280 )]/ε A280

ε D252 =26,159 M −1 cm −1

ε D280 =5,180 M −1 cm −1

ε A280 =224,000 M −1 cm −1

ε A252 =82,880 M −1 cm −1

A 252 and A 280 being the absorbances of the conjugate measured on the UV spectrophotometer at respectively 252 and 280 nm.

9. A conjugate according to claim 8 having an average DAR comprised between 4 and 10.

10. A conjugate according to claim 9 having an average DAR comprised between 5.9 and 7.5.

11. An article of manufacture comprising:

a) a packaging material

b) an antibody or epitope-binding fragment thereof according to claim 3 , or a conjugate according to claim 10 , and

c) a label or package insert contained within said packaging material indicting that said antibody or epitope-binding fragment thereof is effective for treating cancer.

12. An antibody or an epitope-binding fragment thereof according to claim 3 , wherein the paratope of said monoclonal antibody or epitope-binding fragment thereof comprises in the light chain: Arg35 of Loop L1, Tyr54, Arg58 and Asp60 of L2.

13. An antibody or an epitope-binding fragment thereof according to claim 3 wherein the paratope of said monoclonal antibody or epitope-binding fragment thereof comprises in the heavy chain: Thr30, Ala31, Tyr32 and Tyr33 of Loop H1, Asn52, Tyr54, Asn55 and Phe57 of H2 and Glu99, Phe100, Tyr101, Gly102, Tyr103 and Tyr105 of H3.

14. An antibody or an epitope-binding fragment thereof according to claim 3 , wherein said monoclonal antibody or epitope-binding fragment thereof comprises mutation at the position: Thr H28.

15. An antibody or an epitope-binding fragment thereof according to claim 3 , wherein said monoclonal antibody or epitope-binding fragment thereof comprises mutation at one of few of the following positions on the light chain: 35, 26 to 31, 34 to 37, 55, 56, 57, 59 and 94 to 102.

16. An antibody or an epitope-binding fragment thereof according to claim 3 , wherein said monoclonal antibody or epitope-binding fragment thereof comprises mutation at one of few of the following positions on the heavy chain: 28, 54 and 57.

17. An antibody or an epitope-binding fragment thereof according to claim 3 , which specifically binds to an epitope of human EphA2 receptor comprising residues Gly49, Lys50, Gly51, Asp53, Cys70, Asn71, Val72, Met73, Ser74, Gly75, Gln77, Phe108, Pro109, Gly110, Gly111, Ser113 and Ser114 of the LBD from the extra-cellular domain of EphA2 receptor, or a conservatively substituted form thereof.

18. An antibody or an epitope-binding fragment thereof according to claim 1 , wherein said heavy chain comprises the amino acid sequence SEQ ID NO: 18, and wherein said light chain comprises the amino acid sequence SEQ ID NO: 16.

19. A method for preparing a conjugate comprising the steps of:

(i) bringing into contact an optionally-buffered aqueous solution of a cell-binding agent with a solution of a cytotoxic compound;

(ii) then optionally separating the conjugate which was formed in (i) from the unreacted reagents and any aggregate which may be present in the solution;

wherein the cell-binding agent is an antibody according to claim 3 , and a cytotoxic agent chosen between:

the compound of formula (XVII):

wherein Y is N-succinimidyloxy, N-sulfosuccinimidyloxy, N-phthalimidyloxy, N-sulfophthalimidyloxy, 2-nitrophenyloxy, 4-nitrophenyloxy, 2,4-dinitrophenyloxy, 3-sulfonyl-4-nitrophenyloxy, 3-carboxy-4-nitrophenyloxy, imidazolyl, or halogen atom; and

the compound of formula (XVIII):

wherein Y is N-succinimidyloxy, N-sulfosuccinimidyloxy, N-phthalimidyloxy, N-sulfophthalimidyloxy, 2-nitrophenyloxy, 4-nitrophenyloxy, 2,4-dinitrophenyloxy, 3-sulfonyl-4-nitrophenyloxy, 3-carboxy-4-nitrophenyloxy, imidazolyl, or halogen atom.

20. A conjugate obtainable by the method of claim 19 .

21. A conjugate according to claim 20 , said conjugate having a structure chosen between the structures of the formula (XV):

and of the formula (XVI):

wherein Ab is an antibody according to claim 3 and n is an integer comprised between 1 and 15.

22. The antibody-drug conjugate of claim 21 wherein n is comprised between 4 and 7.

23. The antibody-drug conjugate of claim 22 having the structure of formula (XV).

24. A method for treating cancer comprising administering an antibody or epitope-binding fragment thereof according to claim 3 , or a conjugate according to claim 6 .

25. The method of claim 24 wherein the cancer is chosen between carcinoma, including that of the bladder, breast, colon, kidney, liver, lung, ovary, pancreas, stomach, cervix, thyroid and skin; including squamous cell carcinoma; hematopoietic tumors of lymphoid lineage, including leukemia, acute lymphocytic leukemia, acute lymphoblastic leukemia, B-cell lymphoma, T-cell lymphoma, Burkitt's lymphoma; hematopoietic tumors of myeloid lineage, including acute and chronic myelogenous leukemias and promyelocytic leukemia; tumors of mesenchymal origin, including fibrosarcoma and rhabdomyoscarcoma; other tumors, including melanoma, seminoma, tetratocarcinoma, neuroblastoma and glioma; tumors of the central and peripheral nervous system, including astrocytoma, neuroblastoma, glioma, and schwannomas; tumors of mesenchymal origin, including fibrosarcoma, rhabdomyoscarama, and osteosarcoma; and other tumors, including melanoma, xeroderma pigmentosum, keratoactanthoma, seminoma, thyroid follicular cancer and teratocarcinoma.