Previously described epidermal growth factor receptor- (EGFR) driven tumor mouse models develop diffuse tumors, which are dissimilar to human lung tumor morphology and difficult to measure by CT and MRI scans. Scientists at the National Cancer Institute (NCI) have developed and characterized a genetically engineered mouse (GEM) model of human EGFR-driven tumor model (hEGFR-TL) that recapitulates the discrete lung tumor nodules similar to those found in human lung tumor morphology. Individual tumor nodules can be easily measured by live animal imaging and the nodules can be harvested and isolated from surrounding lung tissue post-treatment, making this a more tractable model for human non-small cell lung adenocarcinoma. The lungs express an EGFR transgene that harbors two mutations (‘L858R’ and ‘T790M’) which render the lung tumors resistant to first generation EGFR inhibitors and are useful for evaluating drugs targeting resistant tumors.