An inhibitor of mutant EGFR; selectively inhibits the proliferation of mutant-EGFR-containing PC-9, HCC827, and H1975 cells (GI50s = 13.3, 6.8, and 22 nM, respectively) over wild-type EGFR-containing A431 cells (GI50 = >1,000 nM); increases survival in an H1975 brain orthotopic rat model