Relative therapeutic efficacy of 125I- and 131I-labeled monoclonal antibody A33 in a human colon cancer xenograft

Abstract

A33, a monoclonal antibody that targets colon carcinomas, was labeled with 125I or 131I and the relative therapeutic efficacy of the 2 radiolabeled species was compared in a human colon cancer xenograft system. Methods: Nude mice bearing human SW1222 colon carcinoma xenografts were administered escalating activities of 125I-A33 (9.25-148 MBq) or 131I-A33 (0.925-18.5 MBq), 125I- and 131I-labeled control antibodies, unlabeled antibody, or no antibody. The effects of treatment were assessed using the endpoints of tumor growth delay and cure. Results: Tumor growth delay increased with administered activity for all radiolabeled antibodies. Approximately 4.5 times more activity was required for 12..