Clinical Impact of Nivolumab in Sinonasal Mucosal Melanoma: A 14-Year Single-Center Retrospective Study and Comprehensive Literature Review.

: Sinonasal mucosal melanoma (SNMM) is a rare aggressive malignancy often resected with postoperative irradiation, with some evidence supporting the use of immune checkpoint inhibitors (ICIs). This study explores the potential efficacy and safety of nivolumab in 16 patients with SNMM, and reviews the literature of ICI use in it. : We retrospectively analyzed 16 patients who had pathologically confirmed SNMM treated at Gifu University Hospital over a 14-year period between 2010 and 2024, of whom 11 received nivolumab. Clinical characteristics, treatment modalities, immune-related adverse events (irAEs), progression-free survival (PFS), and overall survival (OS) were examined. Kaplan-Meier and log-rank tests were used for survival analysis. A comprehensive literature review was done regarding ICI in SNMM. : Among the 16 patients, 11 received nivolumab and five did not. The nivolumab group showed longer median survival (median OS 26 mo vs. 8 mo; = 0.00056) and a median PFS of 13 mo vs. 3 mo, = 0.00175. In recurrent cases, nivolumab was associated with longer median OS (23 mo vs. 9 mo, = 0.015) and PFS (11 mo vs. 3 mo, = 0.019). irAEs occurred in four out of eleven of these cases, leading to nivolumab discontinuation; however, three of these four patients maintained durable disease control. A literature review identified generally favorable outcomes for ICIs in SNMM, although results were varied due to small sample sizes and heterogeneous treatment settings. : Nivolumab was associated with longer survival in this small cohort in patients with SNMM, including those who discontinued therapy due to irAEs. Our data supports recent meta-analyses demonstrating a benefit of ICIs in SNMM.