Anti-DPEP3 antibodies and methods of use

1. An antibody drug conjugate comprising a monoclonal antibody conjugated, linked, or otherwise associated with a cytotoxic agent,

wherein the monoclonal antibody binds human DPEP3 and comprises three complementarity determining regions of a light chain variable region set forth as SEQ ID NO: 205 and three complementarity determining regions of a heavy chain variable region set forth as SEQ ID NO: 207.

2. The antibody drug conjugate of claim 1 , wherein mutating at least one of amino acids E217, R242, Q248, Q372, K375, and E379 of SEQ ID NO: 3 results in loss of binding of the antibody to DPEP3.

3. The antibody drug conjugate of claim 1 , wherein the monoclonal antibody binds to an epitope on human DPEP3 that comprises residues E217, R242, Q248, Q372, K375, and E379.

4. The antibody drug conjugate of claim 1 , wherein the monoclonal antibody is a chimeric, CDR grafted, or humanized antibody.

5. The antibody drug conjugate of claim 1 , comprising the formula Ab-[L-D]n, wherein:

a) Ab comprises the antibody;

b) L comprises an optional linker;

c) D comprises a drug, which is the cytotoxic agent; and

d) n is an integer from about 1 to about 20.

6. The antibody drug conjugate of claim 1 , wherein the cytotoxic agent is a pyrrolobenzodiazepine (PBD).

7. A pharmaceutical composition comprising (i) the antibody drug conjugate of claim 1 and (ii) a pharmaceutically acceptable carrier.

8. The antibody drug conjugate of claim 1 , wherein the antibody comprises residues 24-34 of SEQ ID NO: 205 for CDRL1, residues 50-56 of SEQ ID NO: 205 for CDRL2, residues 89-97 of SEQ ID NO: 205 for CDRL3, residues 31-35 of SEQ ID NO: 207 for CDRH1, residues 50-65 of SEQ ID NO: 207 for CDRH2 and residues 95-102 of SEQ ID NO: 207 for CDRH3, wherein the CDR residues are numbered according to Kabat.

9. The antibody drug conjugate of claim 1 , wherein the antibody comprises residues 24-34 of SEQ ID NO: 205 for CDRL1, residues 50-56 of SEQ ID NO: 205 for CDRL2, residues 89-97 of SEQ ID NO: 205 for CDRL3, residues 26-32 of SEQ ID NO: 207 for CDRH1, residues 52-56 of SEQ ID NO: 207 for CDRH2 and residues 95-102 of SEQ ID NO: 207 for CDRH3, wherein the CDR residues are numbered according to Chothia.

10. The antibody drug conjugate of claim 1 , wherein the antibody comprises residues 30-36 of SEQ ID NO: 205 for CDRL1, residues 46-55 of SEQ ID NO: 205 for CDRL2, residues 89-96 of SEQ ID NO: 205 for CDRL3, residues 30-35 of SEQ ID NO: 207 for CDRH1, residues 47-58 of SEQ ID NO: 207 for CDRH2 and residues 93-101 of SEQ ID NO: 207 for CDRH3, wherein the CDR residues are numbered according to MacCallum.

11. The antibody drug conjugate of claim 1 , wherein the antibody comprises residues 24-34 of SEQ ID NO: 205 for CDRL1, residues 50-56 of SEQ ID NO: 205 for CDRL2, residues 89-97 of SEQ ID NO: 205 for CDRL3, residues 26-35 of SEQ ID NO: 207 for CDRH1, residues 50-58 of SEQ ID NO: 207 for CDRH2 and residues 95-102 of SEQ ID NO: 207 for CDRH3, wherein the CDR residues are numbered according to AbM.

12. The antibody drug conjugate of claim 1 , wherein the antibody comprises a light chain variable region set forth as SEQ ID NO: 205 and a heavy chain variable region set forth as SEQ ID NO: 207.

13. The antibody drug conjugate of claim 1 , wherein the antibody comprises two light chains and two heavy chains, wherein each of the two light chains comprises a sequence set forth as SEQ ID NO: 224 and each of the two heavy chains comprises a sequence set forth as SEQ ID NO: 225.

14. The antibody drug conjugate of claim 1 , wherein the antibody comprises two light chains, two heavy chains, and two unpaired cysteine residues.

15. The antibody drug conjugate of claim 14 , wherein each of the two light chains comprises an unpaired cysteine residue.

16. The antibody drug conjugate of claim 15 , wherein the two light chains each comprise an unpaired cysteine residue at position C214.

17. The antibody drug conjugate of claim 14 , wherein each of the two heavy chains comprises an unpaired cysteine residue.

18. The antibody drug conjugate of claim 17 , wherein each of the two heavy chains comprise IgG1 comprising an unpaired cysteine residue at position C220.

19. The antibody drug conjugate of claim 14 , wherein the antibody comprises an IgG1 monoclonal antibody comprising (i) a cysteine residue at heavy chain position 220 and a deletion of a cysteine residue at light chain position 214; (ii) a cysteine residue at heavy chain position 220 and a substitution of a cysteine residue at light chain position 214; (iii) a cysteine residue at light chain position 214 and a deletion of a cysteine residue at heavy chain position 220; or (iv) a cysteine residue at light chain position 214 and a substitution of a cysteine residue at heavy chain position 220; and

wherein the antibody comprises native cysteine residues at heavy chain positions 226 and 229.

20. The antibody drug conjugate of claim 14 , wherein each of the two light chains comprises a sequence set forth as SEQ ID NO: 224 and each of the two heavy chains comprises a sequence set forth as SEQ ID NO: 226.

21. The antibody drug conjugate of claim 1 , wherein the antibody is conjugated to the cytotoxic agent.

22. The antibody drug conjugate of claim 1 , wherein the cytotoxic agent is a pyrrolobenzodiazepine having the structure:

23. The antibody drug conjugate of claim 1 , wherein the antibody comprises a light chain variable region set forth as SEQ ID NO: 205 and a heavy chain variable region set forth as SEQ ID NO: 207 and wherein the cytotoxic agent is a pyrrolobenzodiazepine having the structure:

24. The antibody drug conjugate of claim 1 , wherein the antibody comprises two light chains and two heavy chains, wherein each of the two light chains comprises a sequence set forth as SEQ ID NO: 224 and each of the two heavy chains comprises a sequence set forth as SEQ ID NO: 226, and wherein the cytotoxic agent is a pyrrolobenzodiazepine having the structure:

25. The antibody drug conjugate of claim 1 , wherein the antibody drug conjugate has a drug loading of 2.

26. The antibody drug conjugate of claim 25 , comprising a linker.

27. The antibody drug conjugate of claim 26 , wherein the linker is a cleavable linker.

28. The antibody drug conjugate of claim 27 , wherein the linker comprises a maleimide linker.

29. The pharmaceutical composition of claim 7 , comprising a drug to antibody ratio (DAR) of 1, 2, 3, 4, 5, 6, 7 or 8 each ±0.4.

30. The pharmaceutical composition of claim 7 , comprising a drug to antibody ratio (DAR) of 2±0.4.

31. The pharmaceutical composition of claim 30 , comprising less than 30% of non-predominant antibody drug conjugate species.

32. The pharmaceutical formulation of claim 7 , wherein the antibody drug conjugate further comprises a linker and wherein:

(a) the antibody comprises a light chain variable region set forth as SEQ ID NO: 205 and a heavy chain variable region set forth as SEQ ID NO: 207; and

(b) the cytotoxic agent is a pyrrolobenzodiazepine having the structure:

33. The pharmaceutical composition of claim 7 , wherein the antibody drug conjugate further comprises a linker and wherein:

(a) the antibody comprises two light chains and two heavy chains, wherein the two light chains each comprise a sequence set forth as SEQ ID NO: 224 and the two heavy chains each comprise a sequence set forth as SEQ ID NO: 226; and

(b) the cytotoxic agent is a pyrrolobenzodiazepine having the structure:

34. The pharmaceutical composition of claim 32 , comprising a drug to antibody ratio (DAR) of 1, 2, 3, 4, 5, 6, 7 or 8 each ±0.4.

35. The pharmaceutical composition of claim 32 , comprising a drug to antibody ratio (DAR) of 2±0.4.

36. The pharmaceutical composition of claim 32 , comprising less than 30% of non-predominant antibody drug conjugate species.

37. The pharmaceutical composition of claim 33 , comprising a drug to antibody ratio (DAR) of 2±0.4.

38. The pharmaceutical composition of claim 33 , comprising less than 30% of non-predominant antibody drug conjugate species.