An irreversible inhibitor of mutant EGFRs; inhibits cell proliferation of Ba/F3 cells expressing various EGFR mutations (IC50s= 9-11 nM); selective for mutant EGFRs over wild-type EGFR (IC50 = 830 nM); reduces phosphorylated levels of EGFR, AKT, and ERK and decreases cell viability in NSCLC cells and cells carrying an exon 20 insertion mutation; reduces tumor growth in PC-9/NaqRc2 mouse xenograft model at 50 mg/kg per day