As a landmark advancement in cancer therapeutics, ICIs restore T-cell antitumor activity by obstructing signaling pathways, notably programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) [7]. The gene discussed is PDCD1; the disease is cancer.