RADIOIMMUNODETECTION OF PROSTATE-CANCER BY IN-111-LABELED MONOCLONAL-ANTIBODY AGAINST PROSTATIC ACID-PHOSPHATASE

Purified human prostate acid phosphatase (PAP) was used to generate a specific monoclonal antibody (FC 3001) for detection of PAP expressed by some prostatic carcinomas. DTPA derivatives of MoAb-F(ab')2-fragmen ts were labeled with indium-III chloride. This labeled antibody was te sted in 15 prostate cancer patients who underwent staging pelvic lymph adenectomy; 9 of them received labeled antibody alone whereas 6 receiv ed simultaneous injections of labeled and unlabeled antibody with two dose levels (40 or 80 mg). Biodistribution data obtained by direct blo od measurements and imaging procedures indicated that simultaneous inj ection of unlabeled antibody reduced both the blood elimination rate a nd the accumulation in the liver. Accumulation of the radionuclide in pelvic lymph node metastases was observed in some patients but in a co uple of patients accumulation was noted also in normal lymph nodes. Th e method cannot in its present design replace staging pelvic lymphaden ectomy and further studies are needed for elaboration of clinically us eful radioimmunodetection methods.