1270PEfficacy of immunotherapy in patients with metastatic mucosal or uveal melanoma

Background: Only few studies on limited series of patients have evaluated the efficacy of immunotherapy in patients with metastatic mucosal melanoma (MM) or uveal melanoma (UM). The aim of the study was to assess the objective response rate and survival of patients with metastatic MM or UM treated with anti-CTLA-4 or anti-PD-1. Methods: A multicenter retrospective study was performed in 25 Dermatology Departments in France. All patients with stage IIIC to IV MM or UM who were treated with anti-CTLA-4 or anti-PD-1 between 2008 and 2016 were included. Tumor response was evaluated according to RECISTv1.1 criteria at Week 12, and compared with a second cohort of patients treated with chemotherapy from 2000 to 2016. Overall survival (OS) was evaluated using Kaplan Meier method, and adjusted for main prognostic factors. UM or MM were analysed separately. Results: A total of 439 patients were included, 229 with MM (151 treated with immunotherapy and 78 treated with chemotherapy) and 210 with UM (100 treated with immunotherapy and 110 treated with chemotherapy). Objective response rates of MM to anti-CTLA-4 and anti-PD-1 were 3/76 (3.9%, 95%CI=0.5%-8.3%) and 15/75 (20%, 95%CI=0.9%-29.1%) respectively, versus 11/78 (14.1%, 95%CI=6.4%-21.8%) in patients treated with chemotherapy (p = 0.047 and p = 0.4). No tumor response was observed in UM patients treated with immunotherapy, versus 4/110 responses (3.6%, 95%CI=0.2-7.4%) in patients treated with chemotherapy (p = 0.12). The OS of MM patients treated with immunotherapy was longer than that of patients treated with chemotherapy (p = 0.002), with a median OS of 15.97 [interquartile range (IQR)=6.89-27.12] and 8.82 months [IQR=5.2-14.9], respectively. After adjusting for main prognostic factors, the OS of MM patients treated with immunotherapy remained longer than that of patients treated with chemotherapy (HR = 0.61 [0.4; 0.95], p = 0.028). The adjusted and non-adjusted OS of UM patients treated with immunotherapy was not different from that of patients treated with chemotherapy (HR = 1.06 [0.70; 1.61], p = 0.78) with median of 13.38 months [IQR=6.03-29.57] and 11.02 months [IQR=5.8-23.9], respectively. Conclusions: Anti-PD-1 should be considered for the treatment of patients with advanced MM. The prognosis of metastatic UM remains poor. Legal entity responsible for the study: P. Joly. Funding: Bristol-Myers Squibb. Disclosure: N. Meyer: Consultant or investigator: BMS, MSD, Roche, GSK, Novartis, Amgen, Pierre Fabre. N. Beneton Benhard: Consultant: BMS, Novartis, Roche. J.-P. Arnault: Grant support for Congress: BMS, MSD; Investigator: Novartis. P. Joly: Consultant: BMS. All other authors have declared no conflicts of interest.