The outcome of patients with mucosal melanoma treated with ipilimumab is not defined. To assess the efficacy and safety of ipilimumab in this melanoma subset, we performed a multicenter, retrospective analysis of 33 patients with unresectable or metastatic mucosal melanoma treated with ipilimumab. The clinical characteristics, treatments, toxicities, radiographic assessment of disease burden by central radiology review at each site, and mutational profiles of the patients' tumors were recorded. Available peripheral blood samples were used to assess humoral immunity against a panel of cancer-testis antigens and other antigens. By the immune-related response criteria of the 30 patients who underwent radiographic assessment after ipilimumab at approximately week 12, there were 1 immune-related complete response, 1 immune-related partial response, 6 immune-related stable disease, and 22 immune-related progressive disease. By the modified World Health Organization criteria, there were 1 immune-related complete response, 1 immune-related partial response, 5 immune-related stable disease, and 23 immune-related progressive disease. Immune-related adverse events (as graded by Common Terminology Criteria for Adverse Events version 4.0) consisted of six patients with rash (four grade 1, two grade 2), three patients with diarrhea (one grade 1, two grade 3), one patient with grade 1 thyroiditis, one patient with grade 3 hepatitis, and 1 patient with grade 2 hypophysitis. The median overall survival from the time of the first dose of ipilimumab was 6.4 months (range: 1.8-26.7 months). Several patients demonstrated serologic responses to cancer-testis antigens and other antigens. Durable responses to ipilimumab were observed, but the overall response rate was low. Additional investigation is necessary to clarify the role of ipilimumab in patients with mucosal melanoma.
Keywords: CTLA-4; Cancer-testis antigens; Immunotherapy; Ipilimumab; Mucosal melanoma.