CA6 Antigen-Specific Cytotoxic Conjugate and Methods of Using the Same

Abstract

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.