PDCD1 and non-small cell lung carcinoma: Targeted therapies, consisting of tyrosine kinase inhibitors (TKI) for oncogene-addicted NSCLC or immuno-checkpoint inhibitors (ICIs) for non-oncogene-addicted tumors with elevated expression of programmed cell death 1 (PD-L1), have significantly improved the outcome of NSCLC patients, although the prognosis of stage 4 patients remains dismal.