Abstract 2122: Enhanced anticancer efficacy via ROS-dependent ferroptosis: Synergy between surufatinib and cisplatin in small cell lung cancer

Abstract Objective: Small cell lung cancer (SCLC), a highly malignant subset of neuroendocrine carcinoma, accounts for 13% of lung cancer cases and is characterized by its high aggressiveness and poor prognosis. The longstanding first-line treatment, a platinum-etoposide chemotherapy regimen, is increasingly compromised by resistance issues, highlighting the critical need for new therapeutic approaches. Surufatinib, an inhibitor selectively targeting vascular endothelial growth factor receptors (VEGFR) 1, 2, and 3, fibroblast growth factor receptor type 1 (FGFR1), and colony-stimulating factor-1 receptor (CSF-1R), has demonstrated efficacy in a spectrum of solid tumors, including neuroendocrine neoplasm, thyroid cancers and biliary cancers. Recently, ferroptosis, an iron-dependent cell death pathway, offers therapeutic promise, especially by inhibiting the xCT system, effective in pancreatic and lung adenocarcinomas. Yet, surufatinib's potential for inducing ferroptosis in SCLC remains to be investigated. Methods: Cytotoxicity assays were performed on SCLC cell lines to assess the combinatorial effect of surufatinib and cisplatin, revealing a synergistic interaction. Ferroptosis inhibitors were applied to assess the reversal of cytotoxic effects. Mitochondrial morphology, reactive oxygen species (ROS) accumulation, membrane potential dissipation (JC-1 assay), lipid peroxidation (MDA levels), and intracellular iron accumulation (Fe2+ quantification) assays confirmed ferroptosis induction. Western blot analyses were conducted to explore the mechanistic pathways, supplemented by in vivo antitumor efficacy evaluations. Results: In vitro assays revealed that surufatinib, when combined with cisplatin, exerts a pronounced synergistic effect on small cell lung cancer (SCLC) cell lines by inducing ferroptosis. The combination therapy strategically modulated ferroptosis-related pathways: cisplatin effectively decreased the expression of glutathione peroxidase 4 (GPX4), critical for cellular antioxidant defenses, while surufatinib increased the expression of acyl-CoA synthetase long-chain family member 4 (ACSL4), which is essential for the accumulation of lipid peroxides. This dual pathway engagement significantly amplified the ferroptotic response, culminating in heightened antitumor activity. Corroborative in vivo experiments substantiated these findings, validating the combined treatment's efficacy in a living model and underscoring its potential as a robust therapeutic strategy for SCLC. Conclusion: Our findings reveal that surufatinib triggers ferroptosis in small cell lung cancer—a novel discovery. Additionally, it also unveils that surufatinib and cisplatin together enhance anti-cancer efficacy via the ROS-mediated ferroptosis pathway, marking a significant advance in SCLC therapy. Citation Format: Xiaolin Li, Ziting Zhang, Qiyun Tang, Huae Xu. Enhanced anticancer efficacy via ROS-dependent ferroptosis: Synergy between surufatinib and cisplatin in small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2122.