Immunoreactivity with the anti-MAGE antibody 57B in malignant melanoma: Frequency of expression and correlation with prognostic parameters

The melanoma-associated antigen (MAGE) family consists of a number of antig ens initially recognized by cytotoxic T lymphocytes, which are currently be ing investigated for immunotherapy of patients with metastatic melanoma and other tumor types. Expression of MAGE mRNA in melanocytic tumors is said t o be restricted to invasive malignant tumors and absent in nevi. Recently, a monoclonal antibody (57B) has become available to examine MAGE protein ex pression in archival material. In this study, we performed immunohistochemi cal analysis on 132 melanocytic nevi and 205 melanomas (85 primary cutaneou s melanomas and 120 metastatic tumors) to determine the frequency of MAGE e xpression and to explore a potential correlation with various prognostic pa rameters. None of the melanocytic nevi and none of the 20 in situ melanomas was immunopositive with the antibody 57B. Immunoreactivity was present in 17 of 65 (26%) primary invasive melanomas of the skin and in 30 of 120 (25% ) metastatic tumors, Positive immunostaining did not correlate with tumor s tage (P =.66), Breslow thickness (P =.39), Clark level (P =.5), or the hist ologic type of melanoma (P =.23) but was associated with a brisk infiltrate of lymphocytes involving the vertical growth phase of melanomas (P =.01). Because tumor-infiltrating lymphocytes in melanoma are associated with long er survival, our findings suggest a potential prognostic role for MAGE. Fur thermore, the seeming restriction of immunopositivity to invasive malignant tumors suggests a potential diagnostic role for the antibody 57B in confir ming the malignant potential of a melanocytic tumor.