RADIOIMMUNOTHERAPY OF EXPERIMENTAL PANCREATIC-CANCER WITH I-131-LABELED MONOCLONAL-ANTIBODY PAM4

We examined the therapeutic efficacy of I-131-labeled murine monoclona l antibody (MAb) PAM4 against human pancreatic cancers carried as xeno grafts in athymic nude mice. Animals bearing the CaPanI tumor (0.2 cm( 3)) were either untreated or were given, I-131-labeled nonspecific Ag8 antibody. By week 7 mean tumor size had grown 16.5 +/- 8.4-fold and 4 .2 +/- 2.5-fold for the untreated and I-131-Ag8-treated animals, respe ctively, In contrast, animals administered I-131-PAM4 exhibited marked regression of tumors to an average of 15% of initial tumor volume. Si nce most pancreatic cancer patients present with large tumor burdens, the limitation of I-131-PAM4 treatment with respect to initial tumor s ize was investigated in animals bearing tumors of approximately 0.5 cm (3), 1.0 cm(3) and 2.0 cm(3). Significant extension of survival time ( >3-fold increase) was noted for both the 0.5 cm(3) and 1.0 cm(3) I-131 -PAM4-treated groups, compared to their respective untreated controls, Even in the group bearing large 2.0-cm(3) tumors, survival was increa sed 2-fold over the control group, To further improve anti-tumor effec ts in large tumors, 2 injections of I-131-PAM4 were administered at a 4-week interval to animals bearing tumors of approximately 1.0 cm(3). Significant extended survival was noted for the group receiving 2 dose s when compared to the group receiving only 1 dose. (C) 1997 Wiley-Lis s, Inc.