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

Citation
Ec. Barendswaard et al., Relative therapeutic efficacy of I-125- and I-131-labeled monoclonal antibody A33 in a human colon cancer xenograft, J NUCL MED, 42(8), 2001, pp. 1251-1256
Citations number
18
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Medical Research Diagnosis & Treatment
Journal title
JOURNAL OF NUCLEAR MEDICINE
ISSN journal
01615505 → ACNP
Volume
42
Issue
8
Year of publication
2001
Pages
1251 - 1256
Database
ISI
SICI code
0161-5505(200108)42:8<1251:RTEOIA>2.0.ZU;2-N
Abstract
A33, a monoclonal antibody that targets colon carcinomas, was labeled with I-125 or I-131 and the relative therapeutic efficacy of the 2 radiolabeled species was compared in a human colon cancer xenograft system. Methods: Nud e mice bearing human SW1222 colon carcinoma xenografts were administered es calating activities of I-125-A33 (9.25-148 MBq) or I-131-A33 (0.925-18.5 MB q), I-125- and I-131-labeled control antibodies, unlabeled antibody, or no antibody. The effects of treatment were assessed using the endpoints of tum or growth delay and cure. Results: Tumor growth delay increased with admini stered activity for all radiolabeled antibodies. Approximately 4.5 times mo re activity was required for I-125-A33 to produce therapeutic effects that were equivalent to those of I-131-A33. This ratio was approximately 7 for a nonspecific, noninternalizing isotype-matched, radiolabeled control antibo dy. Unlabeled A33 antibody had no effect on tumor growth. Approximately 10 times more activity of I-125-A33 produced toxicity similar to that of I-131 -A33, and this ratio fell to approximately 6 for radiolabeled control antib ody. Conclusion: Treatment with I-125-A33 resulted in a relative therapeuti c gain of approximately 2 compared with I-131-A33 in this experimental syst em.