Bifunctional Proteins Combining Checkpoint Blockade for Targeted Therapy

Abstract

Provided are bispecific proteins that comprise a binding domain binding cell surface protein and a vascular endothelial growth factor (VEGF) inhibiting domain. Provided also is an antibody-drug conjugate that comprises a therapeutic agent and an antibody or an antigen-binding fragment binding PD-L1 and/or a VEGF inhibiting domain, wherein the therapeutic agent is covalently conjugated to the antibody or the antigen-binding fragment by a linker.

What is claimed is: 
     
         1 . A fusion protein comprising an antibody or antigen-binding fragment thereof that comprises an at least one polypeptide chain, the at least one polypeptide chain comprising:
 a binding domain binding cell surface protein, wherein the binding domain binds programmed cell death protein 1 ligand (PD-L1), and the binding domain comprises:   a heavy chain variable region comprising complementarity-determining regions (CDRs) CDR1, CDR2, and CDR3 set forth in the sequence of SEQ ID NO: 6 and a light chain variable region comprising CDR1, CDR2, and CDR3 set forth in amino acid 1-110 of SEQ ID NO: 5; and   a vascular endothelial growth factor (VEGF) inhibiting domain comprising the amino acid sequence of SEQ ID NO: 9.   
     
     
         2 . The fusion protein of  claim 1 , wherein the at least one polypeptide chain further comprises:
 an Fc domain; and   an Fab fragment connected to the N-terminus of the Fc domain, the Fab fragment comprising the binding domain,   wherein the VEGF inhibiting domain is connected to the C-terminus of the Fc domain.   
     
     
         3 . The fusion protein of  claim 2 , further comprising a linker between the Fc domain and the VEGF inhibiting domain. 
     
     
         4 . The fusion protein of  claim 1 , wherein the antibody or antigen-binding fragment thereof comprises one or more pairs of polypeptide chains. 
     
     
         5 . The fusion protein of  claim 4 , wherein the antibody is an IgG, IgE, IgM, IgD, IgA, or IgY antibody. 
     
     
         6 . The fusion protein of  claim 5 , wherein the antibody is an IgG antibody. 
     
     
         7 . The fusion protein of  claim 6 , wherein the IgG antibody is an IgG1, IgG2, IgG3, or IgG4 antibody. 
     
     
         8 . The fusion protein of  claim 7 , wherein the IgG1 antibody is a reduction of antibody-dependent cell-mediated cytotoxicity of IgG1 antibody. 
     
     
         9 . The fusion protein of  claim 1 , wherein the antibody is a human antibody. 
     
     
         10 . The fusion protein of  claim 1 , wherein the heavy chain variable region comprises a sequence that is at least 90% sequence identity to the sequence to SEQ ID NO: 6,
 wherein the light chain variable region comprises a sequence that is at least 90% sequence identity to the sequence to amino acids 1-110 of SEQ ID NO: 5, and   wherein the at least 90% sequence identity to the sequence to amino acids 1-110 of SEQ ID NO: 5 and to the sequence to SEQ ID NO: 6 excludes CDRs.   
     
     
         11 . The fusion protein of  claim 1 , further comprising a therapeutic agent, wherein the therapeutic agent is covalently conjugated to the antibody or the antigen-binding fragment in the fusion protein by a linker. 
     
     
         12 . A pharmaceutical composition, comprising:
 the fusion protein of  claim 1 , and   at least one pharmaceutically acceptable carrier.   
     
     
         13 . A fusion protein comprising an antibody or antigen-binding fragment thereof that comprises an at least one polypeptide chain, the at least one polypeptide chain comprising:
 a heavy chain variable region and a light chain variable region respectively, wherein the heavy chain variable region comprises complementarity-determining regions CDR1, CDR2, and CDR3 set forth in the sequence of SEQ ID NO: 6, and wherein the light chain variable region comprises complementarity-determining regions CDR1, CDR2, and CDR3 set forth in amino acid 1-110 of SEQ ID NO: 5; and   a VEGF inhibiting domain comprising the amino acid sequence of SEQ ID NO: 9.   
     
     
         14 . The fusion protein of  claim 13 , wherein the heavy chain variable region comprises a sequence that is at least 90% sequence identity to the amino acid sequence of SEQ ID NO: 6,
 wherein the light chain variable region comprises a sequence that is at least 90% sequence identity to the amino acid sequence of amino acids 1-110 of SEQ ID NO: 5, and   wherein the at least 90% sequence identity to the sequence to amino acids 1-110 of SEQ ID NO: 5 and to the sequence to SEQ ID NO: 6 excludes CDRs.   
     
     
         15 . The fusion protein of  claim 13 , wherein the antibody is a human antibody.