Non-smoking HNSCC patients had a significantly greater proportion of programmed death-ligand 1 (PD-L1)-positive cells in the microenvironment of HNSCC and had a higher response rate to anti-programmed death 1 (PD-1) checkpoint inhibitors than smoking HNSCC patients [19, 20]. The gene discussed is CD274; the disease is head and neck squamous cell carcinoma.