P9-8 Retrospective analysis of the safety and effectiveness of immune checkpoint inhibitors in mucosal melanoma patients

In Japanese populations, the primary sites of melanoma are cutaneous (%) and mucosal (8%). Mucosal melanoma is an aggressive malignancy with a poor response to immune checkpoint inhibitor compared with cutaneous melanoma.We reviewed the safety and effectiveness of immune checkpoint inhibitors in mucosal melanomapatients. We retrospectively analyzed mucosal melanoma patients treated with immune checkpoint inhibitor in our department from December 2014 to September 2021. 8 patients were included in this study. The median age was 73 (range 49-83) and 7 people were male. Primary sites were esophageal/rectum: 6/2. Staging were IV/postoperative recurrence : 7/1. 1st line Chemotherapy choice were Nivolumab/ Pembrolizumab / Nivolumab + Ipilimumab : 4/1/3. The median PFS was 164 (range 14-204). Best overall response were PD/SD/PR : 3:3:2. All patients treated with ICI combination therapy were experienced grade 3 irAE(hepatic disorder, encephalopathy and myocarditis). The effect of ICI for mucosal melanoma was recognized in our study, but ICI combination therapy may lead severe irAE and that adverse events may be life threatening for advanced melanoma patients.