A new series of AZD9291 (osimertinib) derivatives containing a sulfoxide side chain at the C-4 position of an aniline moiety were designed, synthesized and evaluated. Among these derivatives, the chiral sulfoxide derivative (-)-41 exhibited excellent inhibition of EGFR kinase activity and L858R/T790M double mutant cell proliferation, with IC50 values of 4.10 nM and 10 nM, respectively. A mechanism study elucidated that (-)-41 induced cell apoptosis and reduced phosphorylation of EGFR and AKT in a dose-dependent manner. Furthermore, (-)-41 exhibited very little apparent toxicity toward three non-tumorigenic cell lines and was less toxic than AZD9291. Moreover, the remarkable exposure (AUCO-inf: 1294.74 h ng/mL), oral bioavailability (73.69%), and relatively shorter half-life (t(1/2) = 1.12 h) of (-)-41 displayed its favorable pharmacokinetic properties. Finally, the antitumor activity of (-)-41 in vivo resulted in a significant reduction of the tumor volume (TGI: 9430%). Altogether, these results suggest that (-)-41 warrants further investigation in Non-Small cell lung cancer (NSCLC) therapy. (C) 2019 Elsevier Masson SAS. All rights reserved.