• An in vitro osimertinib resistance evolution model using continuous high-dose drug induction recapitulates clinical resistance and identifies HDAC6 as a key resistance factor.
• HDAC6 is significantly upregulated in osimertinib-resistant NSCLC cells, and its knockdown or pharmacological inhibition restores drug sensitivity.
• HDAC6 overexpression in sensitive cells reduces osimertinib efficacy and accelerates resistance onset, confirming its causal role.
• Mechanistically, HDAC6 promotes EGFR degradation via the ubiquitin-proteasome pathway, suggesting HDAC6 as a novel therapeutic target to overcome osimertinib resistance.