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]. This evidence concerns the gene CTLA4 and cancer.