An irreversible inhibitor of mutant forms of EGFR including T790M (Ki = 21.5 nM) with minimal activity at the wild-type EGFR (Ki = 303.3 nM); inhibits the proliferation of NSCLC cells expressing mutant EGFR (GI50s = 7-32 nM) and demonstrates anti-tumor activity in NSCLC EGFR mutant xenograft and transgenic models