Design, synthesis and biological evaluation of novel aminopyrimidine derivatives as potent EGFRC797S inhibitors for overcoming osimertinib resistance.

Abstract

EGFRC797S mutation and bypass pathway activation are major drivers of acquired resistance to osimertinib; however, no approved therapeutic agents are currently available to effectively overcome this resistance. In this study, a series of aminopyrimidine-based small-molecule inhibitors were rationally designed and synthesized. The lead compound 6a exhibits potent single-digit nanomolar activity against EGFRL858R/T790M/C797S (IC50 = 1.76 nM), along with equipotent ALK inhibitory activity (IC50 = 1.95 nM) that may address ALK-mediated bypass resistance. The co-crystal structure of EGFRC797S in complex with 6a (PDB: 9XU9) reveals a unique hydrogen bond between the inhibitor and Ser797-the residue that confers osimertinib resistance-providing a structural basis for resistance overcoming. In cellular assays, 6a potently inhibits proliferation of osimertinib-resistant H1975-M3 cells (IC50 = 0.035 μM), suppresses downstream oncogenic signaling, induces G0/G1 cell cycle arrest and apoptosis, and impairs cell migration and invasion. In vivo, 6a demonstrates robust antitumor efficacy in an H1975-M3 xenograft model with a tumor growth inhibition rate of 86.47% at 30 mg/kg, significantly outperforming brigatinib (55.53%), while exhibiting favorable safety and pharmacokinetic profiles. Collectively, these findings establish 6a as a promising therapeutic candidate for overcoming osimertinib resistance.