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A cytotoxic agent can be generated selectively at cancer sites
K D Bagshawe1, C J Springer, F Searle
1Department of Medical Oncology, Charing Cross Hospital, London, UK.
British Journal of Cancer
|December 1, 1988
Summary
This study introduces a novel two-stage cancer treatment. An antibody-enzyme conjugate delivered a cancer-killing agent precursor, effectively eradicating human choriocarcinoma xenografts in mice.
Area of Science:
- Oncology
- Immunotherapy
- Biochemistry
Background:
- Antibody-drug conjugates show tumor localization but limited therapeutic success.
- Improving selectivity of anti-cancer agents remains a challenge.
Purpose of the Study:
- To evaluate a two-stage approach for cancer therapy using an antibody-directed enzyme.
- To assess the efficacy of generating a cytotoxic agent in situ at the tumor site.
Main Methods:
- Conjugating carboxypeptidase G2 (CPG2) to an F(ab')2 antibody fragment targeting beta-human chorionic gonadotropin (beta-hCG).
- Administering the conjugate to nude mice with hCG-producing choriocarcinoma xenografts.
- Administering a prodrug, para-N-bis (2-chloroethyl) aminobenzoylglutamic acid, after conjugate localization and clearance from blood.
Main Results:
- The CPG2-antibody conjugate localized to tumor sites.
- CPG2 cleaved the prodrug, releasing a cytotoxic benzoic acid mustard.
- Tumor growth was significantly inhibited by a single treatment course, even in chemo-resistant xenografts.
Conclusions:
- This antibody-directed enzyme approach successfully activated an alkylating agent.
- The method demonstrated potential for eradicating established human cancer xenografts.
- This represents a novel strategy in targeted cancer therapy.