Bifunctional proteins combining checkpoint blockade for targeted therapy

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: 4 and a light chain variable region comprising CDR1, CDR2, and CDR3 set forth in amino acid 1-111 of SEQ ID NO: 3; 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 3 , wherein the antibody comprises the amino acid sequence set forth in SEQ ID NO: 12 or 13.

5. The fusion protein of claim 1 , wherein the antibody or antigen-binding fragment thereof comprises one or more pairs of polypeptide chains.

6. The fusion protein of claim 5 , wherein the antibody is an IgG, IgE, IgM, IgD, IgA, or IgY antibody.

7. The fusion protein of claim 6 , wherein the antibody is an IgG antibody.

8. The fusion protein of claim 7 , wherein the IgG antibody is an IgG1, IgG2, IgG3, or IgG4 antibody.

9. The fusion protein of claim 8 , wherein the IgG1 antibody is a reduction of antibody-dependent cell-mediated cytotoxity of IgG1 antibody.

10. The fusion protein of claim 1 , wherein the antibody is a human antibody.

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. The fusion protein of claim 1 , wherein the heavy chain variable region comprises a sequence that is at least 90% sequence identify to the sequence of SEQ ID NO: 4, and

wherein the light chain variable region comprises a sequence that is at least 90% sequence identify to the sequence of amino acids 1-111 of SEQ ID NO: 3, and

wherein the at least 90% sequence identity to the amino acid sequence of SEQ ID NO: 3 or 4 excludes complementarity-determining regions (CDRs).

13. A pharmaceutical composition, comprising:

the fusion protein of claim 1 , and

at least one pharmaceutically acceptable carrier.

14. 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 complementary-determining regions CDR1, CDR2, and CDR3 set forth in the sequence of SEQ ID NO: 4, and wherein the light chain variable region comprises complementary-determining regions CDR1, CDR2, and CDR3 set forth in amino acid 1-111 of SEQ ID NO: 3;

a vascular endothelial growth factor (VEGF) inhibiting domain comprising the amino acid sequence of SEQ ID NO: 9.

15. The fusion protein of claim 14 , 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: 4,

wherein the light chain variable region comprises a sequence that is at least 90% sequence identity to the amino acid sequence of amino acids 1-111 of SEQ ID NO: 3, and

wherein the at least 90% sequence identity to the amino acid sequences of SEQ ID NO: 3 or 4 excludes complementarity-determining regions (CDRs).