Patent ID: 8252897

Claim:
A modified diphtheria toxin or fragment thereof comprising an amino acid sequence that is at least 90% identical to the full length sequence of SEQ ID NO: 2 or 200 and comprising at least one modified T-cell epitope core comprising at least one amino acid modification in a sequence selected from: i) amino acid residues 97-105 of SEQ ID NO: 2 or 200; ii) amino acid residues 107-115 of SEQ ID NO: 2 or 200; iii) amino acid residues 116-124 of SEQ ID NO: 2 or 200; iv) amino acid residues 124-132 of SEQ ID NO: 2 or 200; v) amino acid residues 148-156 of SEQ ID NO: 2 or 200, wherein any modification at residue 148 is selected from V148A and V148T; and vi) amino acid residues 298-306 of SEQ ID NO: 2 or 200, wherein any modification at residue 298 is selected from L298A and L298N; wherein said modified diphtheria toxin or fragment thereof is cytotoxic and exhibits reduced immunogenicity compared to an unmodified diphtheria toxin.