ICIs play a pivotal role in the treatment of various advanced-stage cancers, as evidenced by monoclonal antibodies blocking the programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) and the cytotoxic T-lymphocyte antigen-4 (CTLA-4) (24). This evidence concerns the gene PDCD1 and cancer.