The introduction of treatments with immune checkpoint inhibitors (ICIs), which target the CTLA-4 (Cytotoxic T-Lymphocyte Associated Protein 4) and PD-1/PD-L1 (Programmed Cell Death-1/Programmed Death-Ligand 1) pathways, among others, has been a breakthrough in the fight against cancer. This evidence concerns the gene CTLA4 and cancer.