PF-299804 is a potent, irreversible pan-ErbB inhibitor, mostly to EGFR with IC50 of 6 nM, effective against NSCLCs with EGFR or ERBB2 mutations (resistant to gefitinib) as well as those harboring the EGFR T790M mutation. 

The epidermal growth factor receptors (EGFR), whose members include erbB-1 (HER1), erbB-2 (HER2), erbB-3 (HER3), and erbB-4 (HER4), are receptor tyrosine kinases that are often over-expressed in cancer.PF-299804 is a second generation pan-erbB receptor tyrosine kinase inhibitor (IC50s = 6, 45.7, and 73.7 nM for erbB-1, erbB-2, and erbB-4, respectively) that irreversibly binds to the ATP site in the catalytic domains of erbB receptors.At 15 mg/kg, it demonstrates antitumor activity ranging from delay in tumor growth to complete regression in various tumor xenograft models expressing either wild-type erbB or mutant erbB family members that show resistance to first generation erbB kinase inhibitors.