Trials with the cytotoxic T-lymphocyte–associated protein 4 (CTLA-4) inhibitor ipilimumab and the programmed cell death protein 1 (PD-1) inhibitors nivolumab and pembrolizumab have shown profound improvements of survival in patients with unresectable or metastatic melanoma.7–9 In a pooled analyses of clinical trials, mucosal melanomas, however, had lower response rates to nivolumab and pembrolizumab compared with cutaneous melanomas.10,11 Data for VVMs are scarce. This evidence concerns the gene PDCD1 and metastatic melanoma.