While initial trials of epacadostat plus the programmed cell death protein 1 (PD-1) inhibitor pembrolizumab in metastatic melanoma were promising, a phase III, double-blinded, randomized trial (ECHO-301/KEYNOTE-252) of epacadostat/pembrolizumab vs. pembrolizumab did not note an additional benefit of epacadostat (23). This evidence concerns the gene PDCD1 and metastatic melanoma.