AZD9291 is a potent, selective, and irreversible, third generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). It inhibits EGFR phosphorylation in EGFR-bearing cells harboring sensitizing EGFR mutants with mean IC50 values ranging from 13 to 54 nM. It also potently inhibits phosphorylation of EGFR in T790M+ mutant cell lines. AZD-9291 displays profound and sustained tumor regression in EGFR-mutant tumor xenograft and transgenic models. MW: 595.71. Purity ≥98% by HPLC