Nazartinib is an irreversible inhibitor of mutant EGF receptors (EGFRs). It is selective for EGFR mutant cell lines, including H3255 and HCC827 lung adenocarcinoma cells (IC50s = 6.11 and 1.52 nM, respectively) and resistant H1975 non-small cell lung cancer cells (NSCLC; IC50 = 4.18 nM), over cells expressing wild-type EGFRs (IC50 = 160.6 nM for HaCaT keratinocytes). Nazartinib decreases phosphorylation of EGFR in H3255, HCC827, and H1975 cells (EC50s = 5, 1, and 3 nM, respectively) and inhibits cell proliferation (EC50s = 9, 11, and 25 nM, respectively) but does not affect cell proliferation in cell lines containing wild-type EGFR. It reduces tumor growth in an HCC827 lung adenocarcinoma mouse xenograft model when administered at doses ranging from 3 to 100 mg/kg per day for 21 days.
egf816 showed sustained inhibition of pegfr, which is consistent with the irreversible binding mechanism of egf816. egf816 also performs exceptionally well in long term dosing studies providing durable responses in the preclinical models .
egf816 demonstrated strong in vivo tumor regressions in several egfr activating and resistant tumor models. in all of the models egf816 inhibited tumor growth dose-dependently and achieved regressions of established tumors at well tolerated doses .
 shailaja kasibhatla, jie li, celin tompkins, mei-ting vaillancourt, jennifer anderson, annemarie culazzo pferdekamper, chun li, oliver long, mathew mcneill, robert epple, debbie liao, eric murphy, steve bender, yong jia, gerald lelais. egf816, a novel covalent inhibitor of mutant-selective epidermal growth factor receptor, overcomes t790m-mediated resistance in nsclc. [abstract]. in: proceedings of the 105th annual meeting of the american association for cancer research; 2014 apr 5-9; san diego, ca. philadelphia (pa): aacr; cancer res 2014;74(19 suppl):abstract nr 1733. doi:10.1158/1538-7445.am2014-1733