GSTA1 Conferred Tolerance to Osimertinib and Provided Strategies to Overcome Drug-Tolerant Persister in EGFR-Mutant Lung Adenocarcinoma.

INTRODUCTION: The generation of drug-tolerant persister (DTP) cancer cells remains a major challenge in treating lung adenocarcinoma (LUAD) patients with EGFR tyrosine kinase inhibitors (TKIs), as these cells eventually drive drug resistance and disease progression. However, the mechanisms underlying DTP formation are poorly understood, limiting therapeutic options upon the emergence of DTP state or resistance after TKI therapy.

METHODS: In this study, we analyzed samples from LUAD patients receiving frontline osimertinib therapy (including baseline, DTP, and stable resistance states) to dissect the cellular and transcriptomic features of TKI-induced DTP cells via single-cell RNA sequencing. Corresponding in vitro/in vivo experiments and external cohort validation were further conducted to validate key findings from clinical sample analysis.

RESULTS: DTP cells exhibited an active drug-metabolizing phenotype, characterized by significantly upregulated GSTA1 expression regulated by RSPH1. Mechanistically, elevated GSTA1 expression in cancer cells promoted osimertinib degradation. Additionally, RSPH1+ DTP cells interacted with macrophages via PROS1-AXL signaling to establish an immunosuppressive tumor microenvironment, contributing to persister formation. Investigation of the RSPH1-CALML4-GSTA1 regulatory axis showed PROS1 expression was also governed by this axis, suggesting GSTA1 acts as an upstream regulator of the PROS1-AXL pathway. The feasibility of osimertinib combined with the GSTA1 inhibitor curzerene was evaluated in osimertinib-induced DTP and acquired resistance mouse models. Notably, this strategy showed superior efficacy compared with osimertinib combinations with chemotherapy or AXL inhibitor in both settings.

CONCLUSION: Collectively, this study elucidated novel mechanisms underlying TKI-induced DTP state and provided a promising combination strategy for overcoming drug tolerance and resistance in osimertinib-treated LUAD patients.