PDCD1 and lung cancer: Here, we have extended these studies to investigate potential mechanisms of adaptive resistance to anti-PD-1 therapy using two fully immunocompetent genetically engineered mouse models of lung adenocarcinomas corresponding to the two most common oncogene drivers in human lung adenocarcinoma, KRAS and EGFR. This study was motivated by the impressive efficacy of anti-PD-1:PD-L1 therapy in lung cancer patients, which has been recently approved by FDA.