RADIOIMMUNOSCINTIGRAPHY WITH A NOVEL MONOCLONAL ANTIPROSTATE ANTIBODY(E4) - AN EXPERIMENTAL-STUDY IN NUDE-MICE

BACKGROUND. Prostate cancer is one of the leading causes of death amon g men, despite achievements in diagnosis and therapy. Radioimmunolocal ization and radioimmunotherapy of malignant tumors have demonstrated i ncreasing potential and may become useful tools in the management of p rostate cancer. METHODS. Nude mice were inoculated subcutaneously with cells from the poorly differentiated human prostate cancer cell line DU-145. The intact monoclonal antibody (MoAb) E4 and an intact anticyt okeratin-8 MoAb, TS1, used for comparison were labeled with I-125 and injected intraperitoneally (i.p.) in the mice. Repetitive quantitative scintigraphic recordings were performed during 1 month. The mice were killed at Day 29 after injection of the radiolabeled MoAb. The tumors and the organs were dissected and weighed. The remaining activity was measured in a gamma well counter. One part of the tumor was immediate ly fixed in Bouin's solution for autoradiography and the other in form aldehyde for microscopy. RESULTS. The study demonstrated significant r adioimmunolocalization of the MoAb E4 into the DU-145 prostate tumor t issue in the animal model, with an average radiation dose of 0.08 Gy/M Bq in the tumor, TS1 localized preferentially in necrotic parts of the tumor, yielding a tumor dose of 0.02 Gy/MBq. CONCLUSIONS. The MoAb E4 is a promising radiotracer for prostate cancer and may be used in rad ioimmunotherapy. As in earlier studies, TS1 shows significant radioimm unolocalization into necrotic tumor tissue, which also exists in prost ate cancer. (C) 1997 American Cancer Society.