Patent ID: 7615225

Claim:
A method of treating a subject having one or more cells expressing the 5T4 cancer antigen, comprising the steps of: (I) administering to a subject a conjugate comprising a bacterial superantigen and an antibody, wherein the superantigen is a variant of Staphylococcal enterotoxin E, reference SEQ ID NO: 7, and differs from Staphylococcal enterotoxin E in comprising amino acid substitutions as follows, wherein the positions of the amino acid substitutions are relative to the amino acid positions in reference SEQ ID NO: 7: (i) amino acid position 20 is glycine or a conserved variant thereof, amino acid position 21 is threonine or a conserved variant thereof, amino acid position 24 is glycine or a conserved variant thereof, amino acid position 27 is lysine or a conserved variant thereof, and amino acid position 227 is serine or alanine, or a conserved variant thereof; and (ii) wherein at least one amino acid in a region C is substituted with a different amino acid, such that the superantigen variant has reduced seroreactivity compared to the seroreactivity of Staphylococcal enterotoxin having the amino acid sequence of SEQ ID NO: 7, and the position of the amino acid substitution in region C is selected from the group consisting of amino acid positions 74, 75, 78, 79, 81, 83 and 84; and wherein the antibody binds 5T4 cancer antigen; and (II) the antibody binding to a 5T4 cancer antigen present on at least one cell in the subject, thereby leading to lysis of said one or more cells expressing the 5T4 cancer antigen.