Development of Potent and Selective EGFR-PROTACs Based on Macrocyclic Fourth-Generation EGFR Inhibitors

Abstract Epidermal growth factor receptor (EGFR) mutant-driven non-small cell lung cancer (NSCLC) frequently develops acquired resistance to third-generation tyrosine kinase inhibitors (TKIs), particularly through the EGFR C797S mutation. Existing EGFR-targeting proteolysis-targeting chimeras (PROTACs) remain limited by unfavorable pharmacokinetics and suboptimal selectivity inherited from their parent TKIs. To address these limitations, we developed HQY1480, a next-generation PROTAC derived from the macrocyclic fourth-generation EGFR inhibitor BI-4020. Systematic linker and E3 ligase ligand optimization enabled potent and selective degradation of multiple clinically relevant EGFR mutants with single-digit nanomolar DC50 values. HQY1480 exhibited favorable pharmacokinetics, stronger suppression of oncogenic signaling than BI-4020, and no detectable off-target degradation in proteomic profiling. In xenograft models, HQY1480 outperformed BI-4020, overcame osimertinib resistance, and effectively inhibited tumor growth at low doses, while inducing robust EGFR degradation in patient-derived xenografts. These findings establish HQY1480 as an effective and well-tolerated lead PROTAC for EGFR-mutant NSCLC with acquired resistance to third-generation TKIs.