Molecular insights into drug resistance mechanisms and therapeutic approaches

Abstract

Leading oncologists increasingly recognize that resistance, not initial response, determines treatment outcomes making resistance mechanism elucidation essential for therapeutic progress. This research investigated molecular mechanisms underlying acquired resistance to targeted therapies in cancer cell models, focusing on kinase inhibitor resistance in non-small cell lung cancer lines. Resistant variants were generated through chronic drug exposure over 30 passages, with characterization including whole-exome sequencing, transcriptomic profiling, and functional validation experiments. Three distinct resistance mechanisms emerged: target mutation (35% of resistant clones), efflux pump upregulation (42%), and bypass pathway activation (23%). The combination of ABCB1 inhibition with primary therapy restored sensitivity in efflux-mediated resistance models, reducing IC50 values by 78.4%. Bypass-resistant clones showed MET amplification in 67% of cases, responding to MET inhibitor combinations. These findings provide mechanistic rationale for combination therapy strategies and identify biomarkers for predicting resistance patterns, enabling proactive therapeutic adaptation.