Modified forms of <i>pseudomonas </i>exotoxin A

摘要

Pseudomonas exotoxin A or “PE” is a 66kD, highly potent, cytotoxic protein secreted by the bacterium Pseudomonas aeruginosa. Various forms of PE have been coupled to other proteins, such as antibodies, to generate therapeutically useful cytotoxin conjugates that selectively target cells of a desired phenotype (such as tumor cells). In the present invention, peptides spanning the sequence of an approximately 38kD form of Pseudomonas exotoxin A protein were analyzed for the presence of immunogenic CD4+ T cell epitopes. Six immunogenic T cell epitopes were identified. Residues were identified within each epitope for introduction of targeted amino acid substitutions to reduce or prevent immunogenic T-cell responses in PE molecules which may be administered to a heterologous host.

主权项

1. A polypeptide having at least one Pseudomonas exotoxin A (PE-A) biological activity, wherein said polypeptide comprises one or more amino acid substitutions compared to a wild-type PE-A polypeptide, wherein said one or more amino acid substitutions is a substitution of a different amino acid at one or more positions corresponding to amino acid residues in the polypeptide of SEQ ID NO:1, wherein one of said substitutions is selected from the group consisting of:
a) arginine (R) at position 146 is substituted with a different basic amino acid; b) arginine (R) at position 146 is substituted with a different polar amino acid residue wherein the substitution at position 146 is not lysine (K) or histidine (H).