MO1-3-6Efficacy and Safety of Nivolumab for Non-Cutaneous Melanoma: A Retrospective Analysis from a Single Institution

Background Non-cutaneous melanoma, including mucosal and uveal melanoma, is a rare neoplasm that accounts for only approximately 1% of all melanomas in the USA and 3.8% in Japan. Several studies have suggested that immune check point inhibitors (ICPis) have lower efficacy against non-cutaneous melanoma than cutaneous melanoma. To evaluate real-world outcomes, we conducted a retrospective analysis of nivolumab for non-cutaneous melanoma. Methods We reviewed 21 patients with unresectable or metastatic non-cutaneous melanoma treated with nivolumab in the first-line setting between Nov 2014 and Dec 2018. Response was assessed every 2-3 months by CT or MRI based on RECIST ver 1.1. Time-to-event analyses were calculated with Kaplan-Meier estimates. Adverse events were evaluated with CTCAE ver 4.0. Results Among the 21 patients, 13 were men and median age was 67 years (range, 47-85). Primary site was the nasal cavity or paranasal sinus/uvea/esophagus/rectum/genital/conjunctiva (n = 11/4/2/2/1/1). BRAF mutation was absent in all tumors. Overall response rate was 19% (95% confidence interval, 35-77%). With median follow-up for survivors of 13.1 months, 1-year overall survival was 59% (median, 8.2 months) and 1-year progression-free survival was 6.6% (median, 2.1 months). Six patients (29%) experienced immune-related adverse events (irAEs), including thyroid dysfunction (n = 4, all grade 2), liver enzyme elevation (n = 3, all grade 2), pigmentary change (n = 2, all grade 1), diabetes mellitus (n = 1, grade 3), and interstitial lung disease (n = 1, grade 2). All these irAEs were manageable. Regarding subsequent treatment, 6 patients received ipilimumab and 1 received pembrolizumab. However, no patient responded to subsequent ICPi. Conclusions In this retrospective analysis, nivolumab showed only modest efficacy against non-cutaneous melanoma and a manageable safety profile. Treatment for the unmet medical needs of non-cutaneous melanoma warrants further investigation.