The use of immunotherapy, particularly immune checkpoint inhibitors (ICIs), such as anti-programmed cell death protein-1 (anti-PD-1) and anti-PD1 ligand (anti-PD-L1) antibodies, has been approved for both first- and second-line treatments of advanced (stage IIIB/IV) non-small cell lung cancer (NSCLC) with relevant improvement in patient survival. The gene discussed is PDCD1; the disease is non-small cell lung carcinoma.