Current clinical ICI applications target CTLA-4, PD-1, or PD-L1 molecules, and the FDA has approved ICI therapies in multiple malignancies, including melanoma, Merkel cell, non-small cell lung, head and neck, gastroesophageal, renal, bladder, and hepatocellular cancers (77, 78). This evidence concerns the gene PDCD1 and melanoma.