Structure-guided discovery of a potent 2-aryl-4-aminoquinazoline-based inhibitor overcoming osimertinib resistance driven by EGFR C797S mutation in NSCLC.

The C797S mutation in epidermal growth factor receptor (EGFR) is a major mechanism of resistance to third-generation tyrosine kinase inhibitors (TKIs), such as Osimertinib, in non-small cell lung cancer (NSCLC), creating an urgent need for effective therapeutic strategies. To address this challenge, we designed the structure-guided optimization of a 2-aryl-4-aminoquinazoline scaffold, leading to the discovery of a potent fourth-generation EGFR inhibitor, compound 6g. The design focused on introducing flexible nitrogen-rich side chains to enable effective non-covalent interaction with the mutant Ser797 residue. Compound 6g exhibited superior activity against EGFRDel19/T790M/C797S with an enzymatic IC50 of 0.056 μM and potently inhibited the proliferation of resistant PC-9 cells (IC50 = 0.143 μM), outperforming the parent lead Angew-1 and Osimertinib by 6-fold and 16-fold, respectively. Further biological evaluation revealed that 6g effectively suppressed proliferation, migration, and induced apoptosis in Osimertinib-resistant cells, concomitant with the inhibition of EGFR and its downstream AKT/MAPK signaling pathways. Favorable pharmacokinetic properties were observed in rats, with an absolute oral bioavailability of 22.33% and a high safety margin (selectivity index >500 in normal human lung epithelial BEAS-2B cells). In a PC-9Del19/T790M/C797S xenograft model, 6g achieved significant dose-dependent tumor growth inhibition (TGI: 47.3% at 5 mg/kg; 64.2% at 10 mg/kg), markedly surpassing Osimertinib (TGI: 16.07% at 10 mg/kg), with no observed significant toxicity. These results establish 6g as a promising fourth-generation EGFR-TKI candidate with potent activity, favorable pharmacokinetics, and a high safety profile, offering a potential therapeutic strategy against Osimertinib resistance driven by the C797S mutation.