Abstract 5554: Intrinsic resistance mechanism of squamous cell lung carcinomas to the multiangiokinase receptor inhibitor Nintedanib through CXCL-1 upregulation in tumor associated fibroblasts

Abstract Background: Lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC) are the most common lung cancer subtypes. SCC is traditionally resistant to anti-angiogenic therapies, though the mechanisms remain unclear. Nintedanib, a multi-angiokinase receptor inhibitor, is approved for treating ADC in combination with docetaxel, based on selective efficacy in the LUME-1 trial. It is also FDA-approved for idiopathic pulmonary fibrosis due to its antifibrotic properties. Both ADC and SCC feature fibrotic stroma rich in activated tumor-associated fibroblasts (TAFs). Our prior work showed Nintedanib has stronger antifibrotic effects on ADC-TAFs than SCC-TAFs. However, its impact on TAF-driven angiogenesis and the role of TAFs in SCC resistance to multi-angiokinase inhibitors remain unexplored. Methods: The pro-angiogenic activity of TAFs secretome from ADC and SCC patients was assessed. TAFs were stimulated with TGF-β1 to mimic their activated phenotype, then treated with Nintedanib. Conditioned media from treated TAFs was used to assess endothelial cell migration and vascular network formation. Pro-angiogenic factor secretion was analyzed using antibody arrays, and functional roles of selected proteins were validated in vitro and in vivo using genetic approaches. Results: Nintedanib inhibited the pro-angiogenic effects of ADC-TAF secretome but paradoxically enhanced angiogenesis in SCC-TAFs, increasing endothelial cell migration in vitro and in vivo. Notably, Nintedanib selectively upregulated CXCL-1 secretion in SCC-TAFs. Silencing CXCL-1 using siRNA in SCC-TAFs abrogated the Nintedanib-induced angiogenesis. Similar findings with other multi-angiokinase inhibitors suggest aberrant CXCL-1 production in SCC-TAFs may drive universal resistance to these therapies. Conclusion: SCC-TAFs are resistant to the anti-angiogenic effects of Nintedanib, which paradoxically promotes angiogenesis via CXCL-1 upregulation. This study provides the first mechanistic insight into SCC resistance to anti-angiogenic therapies and underscores the critical role of TAFs in modulating therapeutic responses. Targeting CXCL-1 or TAF-mediated pathways may inform alternative anti-angiogenic strategies in SCC, potentially in combination with immune checkpoint inhibitors. Citation Format: Natalia Isabel Diaz Valdivia, Paula Duch, Alejandro Bernardo, Marselina Arshakyan, Noemi Reguart, Derek Radisky, Oriol Casanovas, Jordi Alcaraz. Intrinsic resistance mechanism of squamous cell lung carcinomas to the multiangiokinase receptor inhibitor Nintedanib through CXCL-1 upregulation in tumor associated fibroblasts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5554.