1323PImmune checkpoint inhibitors in a cohort of 206 metastatic uveal melanomas patients

Abstract Background Uveal melanomas (UM) are BRAF-wild type tumors associated with dismal prognosis for which no systemic therapy is active. We report our experience with immune checkpoint inhibitors (ICI) in metastatic UM patients. Methods Ambispective cohort of metastatic UM patients treated with ICI in eight French centers. Response rate, progression-free survival (PFS) and overall survival were retrieved. Results 206 evaluable patients started their first ICI treatment between December 2012 and January 2019. The population consisted of 98 men and 108 women. Median age was 57.5 yo (19; 82). Seventy-four patients had been enucleated, 131 had received proton beam therapy, one had received brachytherapy. The median time to first metastasis was 29.4 months (0-380.4). ICI were first prescribed in first-line in 68 patients, in second-line in 79 patients, in third-line or more in 80 patients. One hundred forty-four patients received pembrolizumab (63%), 58 nivolumab (25%) and 21 ipilimumab (9%). Metastatic sites at initiation of ICI were liver, lung, skin, and bone for 201, three, one and one patients, respectively. Liver was the sole metastatic site in 201 patients. Patients received a median number of four ICI infusions (1-60+). Treatment was suspended because of immune side effects in 21 patients. Nine objective responses were observed (four complete and five partial responses; 4.4%) including one patient with a hypermutated, MBD4-deficient tumor. Fifty-seven patients showed stable disease as best response (27.7%). Median PFS in the whole cohort was 4.1 months (0; 30.4) in 1st line, 4.9 months (0; 42,6) in 2nd line and 3.1 (1; 17.,3) months in 3rd line. Median PFS was 4.1 months in the ICI-resistant population and 27.4 months in the ICI-sensitive population (log-rank p-test Conclusions ICI are associated with a low response rate in UM but with longer PFS and a trend for longer overall survival in ICI-sensitive tumors. Immunotherapies should be investigated in this disease. ICI-sensitive cases are currently being explored to identify biomarkers of response. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.