Immune checkpoint inhibitors (ICIs) have been identified as a major advancement in cancer treatment, with their capacity to target the interaction between programmed cell death 1 (PD1) and programmed cell death ligand 1 (PD-L1), as well as their ability to block cytotoxic T lymphocyte antigen 4 (CTLA-4), resulting in enhanced precision and efficacy in treatment. The gene discussed is PDCD1; the disease is cancer.