ANTl-5T4 ANTIGEN BINDING DOMAINS, ANTIBODY-DRUG CONJUGATES AND METHODS OF USE THEREOF

A method of treating cancer in a subject in need thereof, the method comprising administering to a subject in need thereof a therapeutically effective amount of an antibody-drug conjugate, wherein the antibody-drug conjugate comprises:

• a. a first antigen binding domain that specifically binds to a first 5T4 epitope;
• b. a second antigen binding domain that specifically binds to a second 5T4 epitope that is not the same as the first 5T4 epitope;
• and
• c. a chemotherapeutic agent;
• wherein the first antigen binding domain is operably linked to the second antigen binding domain.

An antigen binding domain comprising a heavy chain variable region domain and a light chain variable region domain;

• wherein the heavy chain variable region domain comprises:
• a. a heavy chain (HC) complementarity determining region (CDR1) sequence selected from the group consisting of SEQ ID NOs:
• 1, 4, and 13-23, or a sequence having 1, 2 or 3 substitutions, insertions or deletions relative thereto;
• b. a HC CDR2 sequence selected from the group consisting of SEQ ID NOs:
• 2, 5, and 24-39, or a sequence having 1, 2 or 3 substitutions, insertions or deletions relative thereto;
• and
• c. a HC CDR3 sequence selected from the group consisting of SEQ ID NOs:
• 3, 6, and 40-52, or a sequence having 1, 2 or 3 substitutions, insertions or deletions relative thereto;
• and
• wherein the light chain variable region domain comprises:
• a. a light chain (LC) complementarity determining region (CDR1) sequence selected from the group consisting of SEQ ID NOs:
• 7, 10, and 53-66, or a sequence having 1, 2 or 3 substitutions, insertions or deletions relative thereto;
• b. a LC CDR2 sequence selected from the group consisting of SEQ ID NOs:
• 8, 11, and 67-75, or a sequence having 1, 2 or 3 substitutions, insertions or deletions relative thereto;
• and
• c. a LC CDR3 sequence selected from the group consisting of SEQ ID NOs:
• 9, 12, and 76-83, or a sequence having 1, 2 or 3 substitutions, insertions or deletions relative thereto.