IMMUNOSCINTIGRAPHY IN PATIENTS WITH COLORECTAL, OVARIAN, AND PROSTATE-CANCER - RESULTS WITH SITE-SPECIFIC IMMUNOCONJUGATES

Application of monoclonal antibody (MoAb) technology to cancer managem ent is discussed by reviewing the development and clinical evaluation of two MoAb-based immunoscintigraphic agents (In-111-satumomab pendeti de [OncoScint CR/OV-In] and In-111-CYT-356; Cytogen Corporation, Princ eton, NJ). Both agents were prepared using a site-specific MoAb modifi cation method that preserves the immunoreactivity of the radiolabeled immunoconjugate. In-111-satumomab pendetide is an In-111-labeled conju gate of the murine MoAb B72.3, which is directed to TAG-72, an antigen expressed by the majority of adenocarcinomas. By providing informatio n that complements the results of standard radiographic diagnostic mod alities, this imaging agent can aid in the treatment of patients with colorectal or ovarian cancer. Immunoscintigraphy with In-111-satumomab pendetide has been shown to assist in medical-surgical management by detecting occult extrahepatic lesions, clarifying equivocal results of other diagnostic imaging tests, and evaluating the extent and resecta bility of known tumor lesions. In-111-CYT-356 is an In-111-labeled con jugate of the murine MoAb 7E11-C5.3, which is reactive with prostatic carcinoma, benign prostatic hypertrophy, and, to a lesser extent, norm al prostatic tissue. Results of preliminary clinical investigations su ggest that In-111-CYT-356 immunoscintigraphy can be useful for the pre surgical staging of prostatic carcinoma and for the detection of occul t distant disease in patients with negative or equivocal results on st andard imaging tests. Results with these site-specifically radiolabele d immunconjugates demonstrate the clinical utility of MoAb-based imagi ng agents in the treatment of patients with solid tumors.