CA6 Antigen-Specific Cytotoxic Conjugate and Methods of Using the Same
Cytotoxic conjugates comprising a cell binding agent and a cytotoxic agent, therapeutic compositions comprising the conjugate, methods for using the conjugates in the inhibition of cell growth and the treatment of disease, and a kit comprising the cytotoxic conjugate are disclosed are all embodiments of the invention. In particular, the cell binding agent is a monoclonal antibody, and epitope-binding fragments thereof, that recognizes and binds the CA6 glycotope. The present invention is also directed to humanized or resurfaced versions of DS6, an anti-CA6 murine monoclonal antibody, and epitope-binding fragments thereof.
1 . A method of treating a subject having a cancer expressing CA6 glycotope, the method comprising administering to the subject a therapeutically effective amount of a humanized antibody or antigen-binding fragment thereof that binds to glycotope CA6;
wherein the cancer is lung cancer; and
wherein the humanized antibody or antigen-binding fragment thereof that binds to glycotope CA6 comprises a heavy chain variable region and a light chain variable region,
wherein the heavy chain variable region comprises three sequential complementarity-determining regions having amino acid sequences comprising SEQ ID NOS: 1, 21, and 3, respectively, and
wherein the light chain variable region comprises three sequential complementarity-determining regions having amino acid sequences comprising SEQ ID NOS: 4, 5, and 6, respectively.
2 . The method of claim 1 ,
wherein the three sequential complementarity-determining regions of the heavy chain variable region comprise amino acids 31-35, 50-66, and 99-106 of SEQ ID NO: 11, respectively, and
wherein the three sequential complementarity-determining regions of the light chain variable region comprise amino acids 24-33, 49-55, and 88-96 of SEQ ID NO: 8, respectively.
3 . The method of claim 1 , wherein the sequence of the heavy chain variable region is set forth in SEQ ID NOS: 10 or 11.
4 . The method of claim 1 , wherein the sequence of the light chain variable region is set forth in SEQ ID NO: 8.
5 . The method of claim 1 ,
wherein the sequence of the heavy chain variable region is set forth in SEQ ID NO: 11, and
wherein the sequence of the light chain variable region is set forth in SEQ ID NO: 8.
6 . The method of claim 1 , wherein humanized antibody or antigen-binding fragment thereof that binds to glycotope CA6 is conjugated to a cytotoxic agent.
7 . The method of claim 6 , wherein the cytotoxic agent is a maytansinoid.
8 . The method of claim 7 , wherein the maytansinoid is a compound of formula (VIII):
wherein Y 1 ′ represents (CR 7 R 8 ) l (CR 9 ═CR 10 ) p (C≡C) q A o (CR 5 R 6 ) m D u (CR 11 ═CR 12 ) r (C≡C) s B t (CR 3 R 4 ) n CR 1 R 2 S—,
wherein:
A, B, and D, each independently is cycloalkyl or cycloalkenyl having 3-10 carbon atoms, simple or substituted aryl, or heterocyclic aromatic or heterocyclic radical;
R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , and R 12 are each independently H, CH 3 , C 2 H 5 , linear alkyl or alkenyl having from 1 to 10 carbon atoms, branched or cyclic alkyl or alkenyl having from 3 to 10 carbon atoms, phenyl, substituted phenyl or heterocyclic aromatic or heterocyclic radical; and
l, m, n, o, p, q, r, s, t, and u are each independently 0 or an integer from 1 to 5, provided that at least two of l, m, n, o, p, q, r, s, t, and u are not zero at any one time.
9 . The method of claim 8 , wherein R 1 is methyl and R 2 is H.
10 . The method of claim 8 , wherein R 1 and R 2 are methyl.
11 . The method of claim 7 , wherein the maytansinoid is a compound of formula (IX-L), (IX-D), or (IX-D,L):
wherein Y 1 represents (CR 7 R 8 ) l (CR 5 R 6 ) m (CR 3 R 4 ) n CR 1 R 2 S—,
wherein:
R 1 and R 2 are each independently CH 3 , C 2 H 5 , linear alkyl or alkenyl having from 1 to 10 carbon atoms, branched or cyclic alkyl or alkenyl having from 3 to 10 carbon atoms, phenyl, substituted phenyl, heterocyclic aromatic or heterocyclic radical, and in addition R 2 can be H;
R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently H, CH 3 , C 2 H 5 , linear alkyl or alkenyl having from 1 to 10 carbon atoms, branched or cyclic alkyl or alkenyl having from 3 to 10 carbon atoms, phenyl, substituted phenyl or heterocyclic aromatic or heterocyclic radical;
l, m and n are each independently an integer from 1 to 5, and in addition n can be 0; and
May represents a maytansinol which bears the side chain at C-3, C-14 hydroxymethyl, C-15 hydroxy or C-20 desmethyl.
12 . The method of claim 11 , wherein R 1 is methyl and R 2 is H, or R 1 and R 2 are methyl.
13 . The method of claim 7 , wherein the maytansinoid is a compound of formula (X):
wherein Y 1 represents (CR 7 R 8 ) l (CR 5 R 6 ) m (CR 3 R 4 ) n CR 1 R 2 S—,
wherein:
R 1 and R 2 are each independently CH 3 , C 2 H 5 , linear alkyl or alkenyl having from 1 to 10 carbon atoms, branched or cyclic alkyl or alkenyl having from 3 to 10 carbon atoms, phenyl, substituted phenyl, heterocyclic aromatic or heterocyclic radical, and in addition R 2 can be H;
R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently H, CH 3 , C 2 H 5 , linear alkyl or alkenyl having from 1 to 10 carbon atoms, branched or cyclic alkyl or alkenyl having from 3 to 10 carbon atoms, phenyl, substituted phenyl or heterocyclic aromatic or heterocyclic radical; and
l, m and n are each independently an integer from 1 to 5, and in addition n can be 0.
14 . The method of claim 7 , wherein the maytansinoid is DM1 or DM4.
15 . The method of claim 14 , wherein the maytansinoid is DM4.
16 . The method of claim 15 , wherein 1-10 DM4 molecules are linked to the antibody or antigen-binding fragment thereof.