Immune-related adverse events correlate with improved survival in patients with advanced mucosal melanoma treated with nivolumab: A single-center retrospective study in Japan

Immune-related adverse events (irAE) were reported to be associated with better outcomes in various cancers treated with the immune checkpoint inhibitor nivolumab. Considering that their development depends on host immune activation, irAE may reflect antitumor response in mucosal melanoma (MM). This single-center retrospective study including patients with advanced MM receiving nivolumab monotherapy between August 2014 and September 2018 investigated whether the development of irAE was associated with clinical efficacy. The study patients were divided into those with and without irAE, and treatment efficacy and safety were evaluated. The study cohort of 27 patients included 20 (74%), six (22%) and one (4%) patient with primary MM in the head and neck, genitourinary and anorectal regions, respectively. The irAE onset was not significantly associated with the objective response rate in patients while it was significantly associated with the disease control rate. The median progression-free survival in patients with and without irAE was 301 and 63 days, respectively. The median overall survival (OS) in patients with and without irAE was 723 and 199 days, respectively. According to the timing of irAE onset, the OS was better in seven patients who developed irAE after 180 days than in nine patients who developed irAE within 180 days. Although 16 patients (59%) experienced any grade irAE, including three (11%) with grade 3 or more irAE, there were no treatment-related deaths. These results indicated that the development of irAE may correlate with improved survival in patients with MM treated with nivolumab monotherapy. Further studies are necessary to confirm these findings.