Immune checkpoint inhibitors (ICIs), including nivolumab and pembrolizumab, aim to reinvigorate antitumor immune responses that are suppressed by cancer cells by targeting key regulator pathways such as programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) [2, 7, 11]. The gene discussed is PDCD1; the disease is cancer.