However, the advent of immune checkpoint inhibitors (ICI), including drugs that target programmed cell death 1 (PD-1) with or without inhibitors of cytotoxic T-lymphocyte–associated protein 4 (CTLA-4), BRAF, and MEK-targeted therapies, has improved the prognosis (1, 3–6, 12, 13) of metastatic melanoma with nearly half of patients on combination immunotherapy and one in three patients with targeted therapy surviving for 5 years (14). This evidence concerns the gene PDCD1 and metastatic melanoma.