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An Immunotoxin With Greatly Reduced Immunogenicity by Identification and Removal of B Cell Epitopes

An Immunotoxin With Greatly Reduced Immunogenicity by Identification and Removal of B Cell Epitopes

Masanori Onda, Richard Beers, Laiman Xiang, Satoshi Nagata, Qing-Cheng Wang, Ira Pastan

Proc Natl Acad Sci U S A. 2008 Aug 12;105(32):11311-6.

PMID: 18678888

Abstract:

Recombinant immunotoxins are hybrid proteins composed of an Fv that binds to a tumor antigen fused to a bacterial or plant toxin. Immunotoxin BL22 targets CD22 positive malignancies and is composed of an anti-CD22 Fv fused to a 38-kDa fragment of Pseudomonas exotoxin A (PE38). BL22 has produced many complete remissions in drug-resistant Hairy cell leukemia, where many treatment cycles can be given, because neutralizing antibodies do not form. In marked contrast, only minor responses have been observed in trials with immunotoxins targeting solid tumors, because only a single treatment cycle can be given before antibodies develop. To allow more treatment cycles and increase efficacy, we have produced a less immunogenic immunotoxin by identifying and eliminating most of the B cell epitopes on PE38. This was accomplished by mutation of specific large hydrophilic amino acids (Arg, Gln, Glu, Lys) to Ala, Ser, or Gly. The new immunotoxin (HA22-8X) is significantly less immunogenic in three strains of mice, yet retains full cytotoxic and anti-tumor activities. Elimination of B-cell epitopes is a promising approach to the production of less immunogenic proteins for therapeutic purposes.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
IAR42414717	Anti-CD22 antibody produced in rabbit			Price

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