Abstract A058: Investigating metformin as a unique therapeutic for KRAS-mutant non-small cell lung cancer

Abstract Introduction: Non-small cell lung cancer (NSCLC) comprises approximately 85% of lung cancer cases. The 5-year survival rate for NSCLC is about 30%. One of the most common mutations that leads to the development of NSCLC is Kirsten rat sarcoma viral oncogene homologue (KRAS). KRAS is an oncogene that drives several types of fatal cancers through activation of the MEK/ERK and PI3K/AKT pathways which are involved in cell survival, proliferation, and differentiation. Historically, KRAS has been considered “undruggable;” however, several KRAS inhibitors targeting the G12C mutation have been recently developed. Despite these drugs being revolutionary for KRAS-mutant cancers, resistance frequently occurs. Through drug repurposing, metformin, a commonly used anti-diabetic drug, has become a promising anti-cancer agent. However, it remains unclear if metformin could combat KRAS inhibitor resistance in NSCLC. Therefore, the focus of our work is to understand the potential mechanisms of action of metformin in KRAS-mutant NSCLC and investigate the combinatorial effects of metformin and KRAS inhibitors on NSCLC cells. Methods: NSCLC cell lines with either wild-type or mutant KRAS were utilized for experiments. Short-term cell viability (MTS) analysis and long-term colony formation assays were performed to determine the sensitivity of the cell lines to metformin and KRAS inhibitors. Western blot analysis was used to determine the effect of the drugs on downstream signaling pathways. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was applied to determine the intracellular concentration of metformin within NSCLC cell lines. Future studies will include the use of Seahorse to determine metabolic changes. Results: Our preliminary data showed that cell lines with mutant KRAS were more sensitive than the cell lines with wild-type KRAS to metformin-induced growth inhibition. Western blot analysis revealed that metformin treatment potently decreased the levels of p-AKT and p-MAPK in KRAS-mutant cell lines but had little effect on KRAS wild-type cell lines. Using LC-MS/MS, the intracellular accumulation of metformin was determined to be higher in most of the KRAS-mutant NSCLC cell lines compared to KRAS wild-type NSCLC cell lines. Additionally, cell viability assays showed that the potency of KRAS inhibitors was cell-line dependent. When studying the combinatorial effects of metformin and KRAS inhibitors, cell proliferation was drastically reduced in the combination treatment compared to either agent alone. Discussion/Conclusions: Based on our initial findings, metformin functions more effectively to inhibit proliferation in cell lines with mutant KRAS than those with wild-type KRAS. The combination of metformin with KRAS inhibitors appears to result in much more potent inhibition of cell growth than either agent alone. Additional work is underway to define the mechanisms of action of metformin towards KRAS mutant NSCLC. Citation Format: Margaret Larsen, Hui Lyu, CongCong Tan, Yakun Wu, Bolin Liu. Investigating metformin as a unique therapeutic for KRAS-mutant non-small cell lung cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2025 Oct 22-26; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2025;24(10 Suppl):Abstract nr A058.