Lung cancer is the leading cause of cancer mortality. Great advances in non-small cell lung cancer therapy have been seen in the last decade, beginning with the success in treating lung cancer harboring EGFR mutations and ALK-gene rearrangements. The potential of these biomarker-driven therapies has propelled research in biomarker targeted approaches to the forefront of lung cancer research. The successful development of immunotherapeutic agents targeting PD-L1 and PD-1 with an associated non-genomic biomarker has opened a new front in the effort for targeted approaches. Although early-phase lung cancer studies have hinted at the potential to use biomarkers to select patients for allocation to treatment in the conduct of clinical trials, data from late-phase studies have tempered expectations. The data leave unclear the wisdom of routinely restricting enrollment on lung cancer clinical trials to biomarker restricted populations, particularly non-genomic biomarkers.