ROLE OF TC-99M-LABELED MONOCLONAL-ANTIBODY IN THE MANAGEMENT OF MELANOMA PATIENTS

Purpose: A study was performed to assess the usefulness of a radiolabeled monoclonal antibody (MoAb; technetium 99m NR-ML-05 Fab) as a detecting agent, as well as to evaluate its role in the overall decision-making process in the management of cutaneous malignant melanoma. Patients and Methods: Twelve patients with histologically confirmed primary cutaneous melanoma and palpable regional nodes were injected with MoAb NR-ML-05 Fab, radiolabeled with 20 to 30 mCi of 99mTc. Whole-body anterior and posterior images were obtained. Left and right lateral views of the head and anterior and posterior views of the chest, abdomen, pelvis, and extremities were obtained, as were selected single-photon emission computed tomographic (SPECT) views of regional lymph nodes and areas of known or suspected lesions. Results: In nine of 12 patients, clinical and/or MoAb evaluation identified 30 discrete sites of suspected melanoma. The remaining three patients showed no positive sites, and there was no evidence of metastatic melanoma. All 30 sites were examined microscopically, and melanoma was confirmed histologically in 23. The remaining seven were negative. MoAb imaging detected 21 (true-positive) but failed to detect two (false-negative) lesions. Sensitivity was 91% (21 of 23); positive predictive value was 95% (21 of 22). Conclusions: MoAb imaging seems to provide an excellent way to obtain information with regard to the metastatic status of melanoma patients. Immunocytochemistry showed that MoAb (NR-ML-05) is as sensitive as the S-100 antibody and probably more sensitive than the commercially available antimelanoma antibody HMB-45.