RADIOIMMUNODETECTION OF MELANOMA USING In-111–96.5 MONOCLONAL ANTIBODY (In-111–96.5 MoAb)

The purpose of this study was to evaluate In-111–96.5 MoAb as a radiopharmaçeuticl (R) for the detection of melanoma (mel). The 96.5 MoAb targets a 97 kilodalton surface antigen on the mel cells.Labeling was by a bifunctional chelation technique, and resulted in 3–5 mCi of In-111 chelated to 1 mg of antibody (A). The R was administered (Ad) intravenously through a 30–120 minute period. Twenty-two studies were performed in 21 patients (PT), with one PT studied twice. In four PT, unlabeled A was Ad prior to the R. Other PT received from 2–19 mg of unlabeled A mixed with the R. Blood (B) was drawn at multiple times following the infusion to observe R kinetics, and to determine if serum chemistries indicated toxicity (tox).There was no evidence of tox from the R or carrier A. Increasing protein mass slowed the loss of In-111 from B, and appeared to improve lesion detection. 66% of the 73 lesions 1.5 cm or larger were detected. Eight metastases were detected which were not clinically suspected. Five metastases imaged were in the 0.5–1.0 cm size range. Two were scalp metastases, and three were lymph nodes in the anterior cervical triangle of the neck. Liver uptake was a major cause of failure of the R as lesions could not be resolved if they occurred in the liver.We conclude that In-111–96.5 MoAb shows promise as a R for the detection of mel, and warrants further study.