There remains an unmet medical need to develop EGFR TKI agents that effectively target both the single activating mutations of del 19 and L858R, and the secondary resistance mutation T790M, while sparing WT EGFR. Drugs active against the resistance mutation will enable molecularly targeted therapy with a more favorable toxicity profile than the current standard of cytotoxic chemotherapy platinum based doublets. Furthermore, by having a wide margin of selectivity favoring the EGFR mutants versus WT EGFR, PF 06747775 is likely to be positioned to improve patient outcomes from an efficacy and safety perspective.