Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, demonstrating unprecedented efficacy against various advanced solid tumors and hematologic malignancies.1-3 These therapies, including anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4),4 anti-programmed cell death protein 1 (PD-1),5 and anti-programmed death-ligand 1 (PD-L1) agents,6 have significantly improved patient outcomes through either monotherapy or combination approaches. The gene discussed is PDCD1; the disease is cancer.