Immune checkpoint inhibitor immunotherapies have had remarkable anti-tumor effects, through programmed cell death-1 (PD-1) inhibitors (nivolumab and pembrolizumab), or programmed cell death ligand 1 (PD-L1) inhibitors (atezolizumab), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors (ipilimumab) [57]. This evidence concerns the gene PDCD1 and neoplasm.