Leveraging Acquired EGFR-TKI-Resistant Models to Identify MUC16 as a Therapeutic Vulnerability in Lung Adenocarcinoma.

Background/Objectives: Acquired resistance to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) remains a major challenge in the treatment of EGFR-mutant lung adenocarcinoma (LUAD). This study aimed to develop and characterize representative models of acquired EGFR-TKI resistance and to identify potential therapeutic targets mediating this process. Methods: Resistant models of PC9 and LUAD-PDCs were generated using a standardized dose-escalation protocol. The resulting models were characterized by drug response assays, morphology, and transcriptomic sequencing. Candidate target genes were validated across all resistant models using siRNA knockdown followed by re-sensitization assays. Clinical relevance was further examined through analysis of publicly available datasets. Results: These generated models displayed stable resistant phenotypes and unique transcriptomic alterations. Cross-model analysis revealed MUC16 as a consistently upregulated gene associated with resistance. Functional validation demonstrated that MUC16 depletion re-sensitized all resistant models to EGFR-TKIs. Furthermore, analysis of clinical data linked high MUC16 expression to poorer patient outcomes. Conclusions: This study establishes stable in vitro models for investigating acquired resistance in EGFR-mutant LUAD and identifies MUC16 as a functionally validated and clinically relevant mediator of EGFR-TKI resistance, providing a potential therapeutic target for overcoming drug resistance.