The use of immune checkpoint inhibitors targeting programmed cell death protein 1 (PD-1) or programmed death-ligand 1 (PD-L1) has become the standard first-line therapy for advanced non-small cell lung cancer (NSCLC) without actionable oncogenic drivers, with a 5-year survival rate of 10–30%, depending on the PD-L1 expression level. The gene discussed is PDCD1; the disease is non-small cell lung carcinoma.