DISTRIBUTION OF IN-111-LABELED AND I-125 LABELED MONOCLONAL-ANTIBODY 17-1A IN MICE BEARING XENOGRAFTS OF HUMAN PANCREATIC-CARCINOMA HUP-T4

Background. The prognosis of pancreatic adenocarcinoma still remains poor because of the lack of reliable diagnostic tests for early stages of the disease. Monoclonal antibody 17-1A (MoAb 17-1A) has been studied extensively, and the antigen recognized by MoAb 17-1A is expressed by adenocarcinomas of the pancreas and stomach, as well as other normal and malignant epithelial tissues. The potential of MoAb 17-1A was investigated for its ability to detect pancreatic carcinomas. The use of MoAb 17-1A in treatment also was studied. Methods. Immunoreactivity of MoAb 17-1A with human pancreatic carcinoma cell line HuP-T4 was examined histochemically by the avidin-biotinylated enzyme complex method. MoAb 17-1A was labeled with I-125 by the Iodogen method and In-111 using either diethylenetriaminepentaacetic anhydride (cDTPA) or 1-(p-benzyldiazonium) diethylenetriaminepentaacetic acid (aDTPA). After injection in nude mice bearing HuP-T4 xenografts, the biodistribution of In-111- and I-125-labeled MoAb 17-1A was examined at various time points. Results. Positive staining of MoAb 17-1A was noted for HuP-T4 cells. A statistically significant (P < 0.01) greater tumor uptake was observed at 3 days after intravenous injection of I-125-labeled MoAb 17-1A when compared with I-125-labeled nonspecific immunoglobulin G. I-125- and In-111-labeled MoAb 17-1A was concentrated in HuP-T4 carcinoma 1.9-4.8 times higher than in the spleen, heart, liver, and pancreas. Conclusions. MoAb 17-1A was found to bind selectively to human pancreatic carcinoma HuP-T4. Tumor exhibited higher uptake of radiolabeled MoAb 17-1A compared with adjacent normal tissues. These results suggest that MoAb 17-1A may be applicable to the radioimmunodetection and radioimmunotherapy of pancreatic adenocarcinomas.