PDCD1 and melanoma: In 2015, based on several landmark Phase 3 clinical trials demonstrating substantial improvements in objective response and progression-free survival with first-line ICI compared with chemotherapy in patients with stage IV melanoma, the National Cancer Comprehensive Network (NCCN) recommended—and the FDA approved—PD-1 ICI as first-line standard-of-care therapy for such patients.3,4,5,6,7,8,9,10,11 Currently recommended ICI regimens include anti–PD-1 monotherapy with nivolumab or pembrolizumab and combined anti–PD-l and anti–CTLA-4 therapy with nivolumab/ipilimumab.