Therapeutic effect of a radiolabeled monoclonal antibody on human ovarian cancer xenograft in nude mice.

The therapeutic value of 131I-OC125, a radiolabeled monoclonal antibody directed against a human ovarian tumor associated antigen CA125, was examined in an ascites forming intraperitoneal human ovarian carcinoma nude mouse model. Nude mice were injected intraperitoneally with NIH:OVCAR3 cells. Twenty-one days after tumor transplantation, groups of animals were injected intraperitoneally as follows: Group 1 with 200 microCi of 131I-OC125 (n = 20), Group 2 with 200 microCi of 131I (n = 17), Group 3 with 200 microCi of 131I-IgG (n = 21), Group 4 with 60 micrograms of OC125 (n = 18), and Group 5 was left untreated (n = 21). Survival of the tumor-bearing animals was used as the endpoint of the experiment. Mean survivals were found to be 52 +/- 18 days for the 131I-OC125 group, 53 +/- 16 days for the 131I-IgG group, 49 +/- 13 days for the 131I group, 47 +/- 24 days for the OC125 group, and 47 +/- 15 days for the untreated control. These results would indicate no therapeutic advantage of 131I-OC125 over controls in this animal model. However, other approaches using single as well as multiple radiolabeled monoclonal antibodies need to be tested in this model in order to definitely establish the efficacy of this treatment modality.