Structural modifications on indole and pyrimidine rings of osimertinib lead to high selectivity towards L858R/T790M double mutant enzyme and potent antitumor activity

EGFR inhibitors represent a significant milestone for treatment of non-small cell lung cancer, however, they suffer from the acquired drug resistance. Utilizing osimertinib as the lead compound, this work has explored the structural modifications on the indole and pyrimidine rings of osimertinib to generate novel osimertinib derivatives. The in vitro enzymatic and cellular studies showed that the derivatives possessed high selectivity towards double mutant EGFR and potent antitumor activity. Particularly, compound 6b-1, the most active compound, exhibited excellent inhibitory activity against double mutant EGFR (IC50 = 0.18 nM) and wild-type EGFR (IC50 = 2.89 nM) as well as H1975 cells (IC50 = 1.44 nM). Western blot analysis showed that 6b-1 completely inhibited double mutant EGFR and Erk phosphorylation. In vivo test using xenograft model indicated that compound 6b-1 had better antitumor efficacy than osimertinib. More importantly, 6b-1 displayed many advantages in the pharmacokinetic study, including better oral bioavailability and metabolism character.