Antibodies blocking PD-1 or its ligand programmed death-ligand 1 (PD-L1) are available as the standard of care (SoC) to treat various types of cancer,1, 2, 3, 4, 5 but some patients treated with anti-PD-1/PD-L1 therapy do not respond to treatment. The gene discussed is PDCD1; the disease is cancer.