A new RNase-based immunoconjugate selectively cytotoxic for ErbB2-overexpressing cells

We report a new tumor-directed immunoRNase, a chimeric protein made up of an antibody fragment (single-chain Fv fragment) directed to ErbB2, a cell surface receptor. and a non-toxic, human ribonuclease, which upon cell internalization becomes cytotoxic. The immunoRNase is active as a ribonuclease, specifically binds and selectively kills ErbB2-positive cells. ErbB2 is one of the most specific tumor-associated antigens identified so far. overexpressed on tumor cells of different origin. Its choice as target antigen and that of a non-toxic, human RNase as the killer moiety makes this immunoRNase a new. potentially attractive anticancer agent. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.