Engineered superantigen for human therapy

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.