The market release of monoclonal antibodies (mABs) targeting the T-lymphocyte-associated protein-4 (anti-CTLA-4) as the first US Food and Drug Administration approved ICI for advanced-stage melanoma in 2011 was followed by the approval of mAbs targeting other ICIs such as programmed cell death protein-1 (anti-PD-1) and PD-1 ligand (anti-PD-L1) (2, 3). This evidence concerns the gene PDCD1 and melanoma.