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

A33, a monoclonal antibody that targets colon carcinomas, was labeled with (125)I or (131)I and the relative therapeutic efficacy of the 2 radiolabeled species was compared in a human colon cancer xenograft system. Nude mice bearing human SW1222 colon carcinoma xenografts were administered escalatin...

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Bibliographic Details
Published inThe Journal of nuclear medicine (1978) Vol. 42; no. 8; p. 1251
Main Authors Barendswaard, E C, Humm, J L, O'Donoghue, J A, Sgouros, G, Finn, R D, Scott, A M, Larson, S M, Welt, S
Format Journal Article
LanguageEnglish
Published United States Society of Nuclear Medicine 01.08.2001
Subjects
Animals
Antibodies, Monoclonal - therapeutic use
Colonic Neoplasms - pathology
Colonic Neoplasms - radiotherapy
Female
Humans
Iodine Radioisotopes
Membrane Glycoproteins - immunology
Mice
Mice, Nude
Neoplasm Transplantation
Radioimmunotherapy
Radiopharmaceuticals - therapeutic use
Transplantation, Heterologous
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Summary:A33, a monoclonal antibody that targets colon carcinomas, was labeled with (125)I or (131)I and the relative therapeutic efficacy of the 2 radiolabeled species was compared in a human colon cancer xenograft system. Nude mice bearing human SW1222 colon carcinoma xenografts were administered escalating activities of (125)I-A33 (9.25-148 MBq) or (131)I-A33 (0.925-18.5 MBq), (125)I- and (131)I-labeled control antibodies, unlabeled antibody, or no antibody. The effects of treatment were assessed using the endpoints of tumor growth delay and cure. Tumor growth delay increased with administered activity for all radiolabeled antibodies. Approximately 4.5 times more activity was required for (125)I-A33 to produce therapeutic effects that were equivalent to those of (131)I-A33. This ratio was approximately 7 for a nonspecific, noninternalizing isotype-matched, radiolabeled control antibody. Unlabeled A33 antibody had no effect on tumor growth. Approximately 10 times more activity of (125)I-A33 produced toxicity similar to that of (131)I-A33, and this ratio fell to approximately 6 for radiolabeled control antibody. Treatment with (125)I-A33 resulted in a relative therapeutic gain of approximately 2 compared with (131)I-A33 in this experimental system.
ISSN:0161-5505
1535-5667