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Antibody‐guided enzyme therapy of cancer producing cyanide results in necrosis of targeted cells
Author(s) -
Kousparou Christina A.,
Epenetos Agamem A.,
Deonarain Mahendra P.
Publication year - 2002
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.10266
Subject(s) - prodrug , fusion protein , carcinoembryonic antigen , chemistry , immunotoxin , biochemistry , enzyme , antibody , in vivo , in vitro , cytotoxicity , biology , recombinant dna , cancer , immunology , genetics , microbiology and biotechnology , gene
A number of enzyme/prodrug activation approaches for the treatment of cancer have been reported to date with varying success. We describe progress in the development of a system based on a β‐glucosidase enzyme in combination with a naturally occurring “prodrug,” the sugar linamarin, which releases the cytotoxin cyanide. A recombinant fusion protein, composed of an scFv (MFE‐23) reactive against carcinoembryonic antigen (CEA) and a plant‐derived β‐glucosidase (linamarase), was produced and its cytotoxic potential was investigated. The fusion protein was expressed in a supersecretory mutant strain of Saccharomyces cerevisiae and purified by affinity chromatography. Extensive functional in vitro characterisation of the fusion protein showed that it retained antigen binding activity but that its catalytic activity was impaired, a problem not related to its fusion with the scFv. Nevertheless, we demonstrated complete tumour cell killing at doses of prodrug that are completely nontoxic to nontargeted cells. Preliminary in vivo characterisation showed that extensive glycosylation of the fusion protein caused its rapid clearance through the hepatic route. Aggregational properties also led to poor pharmacokinetics. Furthermore, we present some data analysing the mode of cell death resulting from exposure to this system. Enzymic catalysis of the substrate generates cyanide, a metabolic poison that asphyxiates cells and leads them to a necrotic‐like cell death. This system has been called antibody‐guided enzyme nitrile therapy (AGENT). © 2002 Wiley‐Liss, Inc.