Nazartinib mesylate (EGF816 mesylate) is a novel, covalent mutant-selective EGFR inhibitor, with Ki and Kinact of 31 nM and 0.222 min-1 on EGFR(L858R/790M) mutant, respectively. EGFRL858R/T790M|31 nM (Ki)

Nazartinib (EGF816) has inhibitory effect on the mutant cell lines with IC50s of 4, 6, 2 nM in H1975, H3255, and HCC827, respectively, and demonstrates improved ADME and PK properties[1]. Nazartinib (EGF816) shows potent inhibition of pEGFR levels in H3255, HCC827, and H1975 cell lines with EC50 values of 5, 1, and 3 nM, respectively. Nazartinib inhibits cell proliferation, with EC50 values of 9, 11, and 25 nM in H3255, HCC827, and H1975, respectively. Nazartinib has an OC50 (compound concentration at 50% occupancy) value of 2 and 5 nM on HCC827 and H1975, respectively[2].

In H1975 mouse xenograft model, Nazartinib (EGF816; 50 and 20 mg/kg or 25 mg/kg, p.o.) demonstrates dose-dependent efficacy with near complete tumor cells regression at the highest dose tested (50 mg/kg)[1]. In H1975 mouse model, Nazartinib (EGF816; 10 mg/kg, p.o.) induces tumor growth inhibition with a T/C (tumor/control volume) of 29%, and when doses are 30 and 100 mg/kg, tumor regressions are achieved (T/C, -61% and -80%, respectively). In the H3255 xenograft model, Nazartinib (30 mg/kg, p.o.) shows significant antitumor activity. Antiproliferative activity of Nazartinib on 89 lung cancer cell lines indicates that Nazartinib selectively inhibits cell lines containing EGFR with catalytic domain mutations[2].

[1]. Lelais G, et al. Discovery of (R,E)-N-(7-Chloro-1-(1-[4-(dimethylamino)but-2-enoyl]azepan-3-yl)-1H-benzo[d]imidazol-2-yl)-2-methylisonicotinamide (EGF816), a Novel, Potent, and WT Sparing Covalent Inhibitor of Oncogenic (L858R, ex19del) and Resistant (T79 [2]. Jia Y, et al. EGF816 Exerts Anticancer Effects in Non-Small Cell Lung Cancer by Irreversibly and Selectively Targeting Primary and Acquired Activating Mutations in the EGF Receptor. Cancer Res. 2016 Mar 15;76(6):1591-602