Previous studies have reported that tumor mutational burden (TMB) (1–3, 5–7), programmed death-ligand 1 (PD-L1) expression (5, 8), CD8+ T cell infiltration (1, 9, 10), and DNA mismatch repair deficiency (MMRd) (5, 11) could affect the efficacy of PD-1 blockade immunotherapy (5, 12, 13). The gene discussed is PDCD1; the disease is neoplasm.