IMAGING OF MELANOMA WITH I-131-LABELED MONOCLONAL-ANTIBODIES

Abstract

Mouse monoclonal antibodies and Fab fragments specific for p97, a melanoma-associated antigen, were used to image metastatic human melanoma. Preclinical studies in athymic mice showed antigen-specific uptake in melanoma xenografts, and toxicity tests in rabbits gave no evidence for tissue damage after injection of up to 100 times the amount of antibody used in humans. Six patients received 1 mg labeled antibody and 1 patient received 1 mg of labeled Fab. No toxic side effects were observed. All 6 patients had positive scans, visualizing 22 of 25 (88%) of lesions larger than 1.5 cm. In tumors from 2 patients, greater uptake of p97-specific vs. control IgG and Fab, respectively was documented by biopsy. Antibodies to mouse Ig appeared in 3 patients receiving 1 mg or more of radiolabeled mouse antibody.