Lymphocyte activation gene-3 (LAG-3) binding antibody and use thereof

1. An isolated anti-LAG-3 antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises:

(a) a heavy chain variable region CDR1 comprising the sequence SYGIS (SEQ ID NO: 88);

(b) a heavy chain variable region CDR2 comprising the sequence WISAYNGNTNYAQKLQG (SEQ ID NO: 89), and

(c) a heavy chain variable region CDR3 comprising the sequence DGWWELLRPDDAFDI (SEQ ID NO: 90), and

the light chain variable region comprises:

(d) a light chain variable region CDR1 comprising the sequence SGDKLGDKYAY (SEQ ID NO: 91),

(e) a light chain variable region CDR2 comprising the sequence YDSDRPS (SEQ ID NO: 92), and

(f) a light chain variable region CDR3 comprising the sequence QVWDSSSDQW (SEQ ID NO: 93).

2. The antibody of claim 1 , comprising a heavy chain variable region and a light chain variable region, wherein:

(1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43;

(2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 75, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43; and

(3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 77, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43.

3. The antibody of claim 1 , wherein the antibody is a monoclonal antibody, a human antibody, or a chimeric antibody.

4. The antibody of claim 1 , wherein the antibody is an antibody fragment binding to LAG-3.

5. The antibody of claim 4 , wherein the antibody fragment is a Fab, Fab′-SH, Fv, scFv, or (Fab′) 2 fragment.

6. The antibody of claim 1 , wherein the antibody is a full length antibody.

7. The antibody of claim 1 , wherein the antibody is an IgG antibody.

8. The antibody of claim 1 , wherein the antibody is a monospecific antibody.

9. The antibody of claim 1 , wherein the antibody is a multispecific antibody.

10. The antibody of claim 9 , wherein the multispecific antibody is a bispecific antibody.

11. The antibody of claim 10 , wherein the bispecific antibody comprises a second binding domain that binds to a second biomolecule, and wherein the second biomolecule is a cell surface antigen.

12. The antibody of claim 11 , wherein the cell surface antigen is a tumor antigen.

13. An isolated nucleic acid encoding the antibody of claim 1 .

14. The isolated nucleic acid of claim 13 , wherein the antibody is an antibody fragment binding to LAG-3.

15. The isolated nucleic acid of claim 14 , wherein the antibody fragment is a Fab, Fab′-SH, Fv, scFv, or (Fab′) 2 fragment.

16. An antibody immunoconjugate comprising a therapeutic agent that is linked to the antibody of claim 5 .

17. The immunoconjugate of claim 16 , wherein the therapeutic agent is a cytotoxic agent.

18. A pharmaceutical composition comprising the antibody immunoconjugate of claim 16 and a pharmaceutically acceptable carrier.

19. A pharmaceutical composition comprising the antibody of claim 1 and a pharmaceutically acceptable carrier.