Bispecific binding proteins and uses thereof

Abstract

The disclosure generally provides proteins that bind two epitopes (e.g., a first and a second epitope) and that are bivalent for binding to each of the first and second epitopes. The disclosure also provides for specific binding proteins, including antibodies, which bind to a target protein. The disclosure also provides compositions comprising such proteins, nucleic acid molecules encoding such proteins and methods of making such proteins. The disclosure provides methods of inducing an immune response in a subject as well as methods for treating or preventing cancer in a subject by administering the proteins, nucleic acid molecules and/or compositions to the subject.

1 . A protein, comprising:
 a first binding domain (BD1) that binds to a first epitope,   a second binding domain (BD2) that binds to a second epitope, and   an Fc region comprising CH2 and CH3 domains;   
       wherein the Fc region comprises BD2 at a solvent exposed loop in the CH2 domain, the CH3 domain, or at the interface of the CH2 and CH3 domains; and 
       wherein the protein is bivalent for binding to each of the first and second epitopes. 
     
     
         2 - 15 . (canceled) 
     
     
         16 . The protein of  claim 1 , wherein the Fc region comprises BD2 at a solvent exposed loop in the amino acid sequence in the CH2 domain, the CH3 domain, or at the interface of the CH2 and CH3 domain. 
     
     
         17 . The protein of  claim 1  wherein BD2 comprises a single-chain variable fragment (scFv). 
     
     
         18 . The protein of  claim 1  wherein BD1 comprises a binding domain selected from the group consisting of a Fab domain, an scFv, a single domain antibody, and an antibody variable domain. 
     
     
         19 . The protein of  claim 1 , wherein BD1 comprises a Fab domain. 
     
     
         20 . The protein of  claim 19 , wherein the Fab domain is connected to the Fc region via an antibody hinge region. 
     
     
         21 . The protein of  claim 1 , wherein the Fc region comprises a domain selected from the group consisting of an Fc region from an IgG1, IgG2, IgG3, IgG4, IgA, IgM, IgE, and IgD. 
     
     
         22 . The protein of  claim 1  wherein the protein further comprises a protein linker L1 between BD2 and the Fc region. 
     
     
         23 . The protein of  claim 1  wherein the protein further comprises a first protein linker, L1, and a second protein linker, L2, between BD2 and the Fc region. 
     
     
         24 . The protein of  claim 1  wherein BD2 is associated with the Fc region via a protein linker L1. 
     
     
         25 . The protein of  claim 1  wherein BD2 is associated with the Fc region via two protein linkers, L1 and L2. 
     
     
         26 . The protein of  claim 1 , wherein the protein comprises a chimeric heavy chain comprising the following polypeptide domains, from N-terminus to C-terminus
 VH1-CH1-CH2(N-term)-BD2-CH2(C-term)-CH3; and   BD1 comprises a Fab domain;   
       wherein VH1 comprises a heavy chain variable domain of the Fab domain and C H 1 comprises the heavy chain constant domain 1 of the Fab. 
     
     
         27 . The protein of  claim 1 , wherein the protein comprises a chimeric heavy chain comprising the following polypeptide domains, from N-terminus to C-terminus
 VH1-CH1-CH2-BD2-CH3; and   BD1 comprises a Fab domain;   
       wherein VH1 comprises a heavy chain variable domain of the Fab domain and CH1 comprises the heavy chain constant domain 1 of the Fab. 
     
     
         28 . The protein of  claim 1 , wherein the protein comprises a chimeric heavy chain comprising the following polypeptide domains, from N-terminus to C-terminus
 VH1-CH1-CH2-CH3(N-term)-BD2-CH3(C-term); and   BD1 comprises a Fab domain;   
       wherein VH1 comprises a heavy chain variable domain of the Fab domain, CH1 comprises the heavy chain constant domain 1 of the Fab. 
     
     
         29 . The protein of  claim 26 , wherein BD2 comprises an scFv. 
     
     
         30 . The protein of  claim 29 , wherein the scFv comprises, from N-terminus to C-terminus,
 VH2-polypeptide linker-VL2 or VL2-polypeptide linker-VH2;   
       wherein VH2 comprises the heavy chain variable domain of the scFv and VL2 comprises the light chain variable domain of the scFv. 
     
     
         31 . The protein of  claim 26  wherein the protein further comprises a protein linker L1 between BD2 and the Fc region. 
     
     
         32 . The protein of  claim 26  wherein the protein further comprises a first protein linker, L1, and a second protein linker, L2, between BD2 and the Fc region. 
     
     
         33 . The protein of  claim 26 , wherein BD2 is associated via a linker (L1) to the CH2 domain, the CH2 domain, or the interface of the CH2 and CH3 domains of the Fc region. 
     
     
         34 . The protein of  claim 26 , wherein BD2 is associated via two protein linkers, L1 and L2 to the CH2 domain, the CH2 domain, or the interface of the CH2 and CH3 domains of the Fc region.