According to the NCCN guidelines version 2.2016, anti-programmed cell death protein 1 (PD-1) antibodies (nivolumab and pembrolizumab) or the nivolumab/ipilimumab combination can serve as first-line immunotherapy for metastatic/unresectable melanoma, with single use of ipilimumab being recommended as second-line therapy. This evidence concerns the gene PDCD1 and melanoma.