Abstract 3451: Exploring the impact of neoantigen expression on lung tumor development

Abstract Lung adenocarcinoma (LUAD) stands as a formidable challenge in oncology, despite the emergence of immunotherapy as a promising treatment avenue. The dynamic interplay between the immune system and cancer plays a pivotal role in shaping cancer development and progression. Central to this process are neoantigens, tumor-specific antigens recognized by cytotoxic T cells, which trigger the elimination of tumor cells. It has been implicated that the presence of T cells also decreases tumor grade. However, the precise impact of neoantigen expression on LUAD development and progression remains poorly understood. Our lab previously developed a genetically engineered mouse model with the ability to induce expression of a fluorescent neoantigen in oncogenic KRAS, P53-null, tdTomato-expressing lung adenocarcinoma cells. Using this system, we track tumor initiation, progression, and advanced LUAD development across 20 weeks in both immune-deficient and -sufficient settings. Further, tumors initiated in this system give rise to heterogeneous (neoantigen+ and -) tumors, enabling the study of T cell-driven tumor selection. Through multiplexed immunofluorescence, we identified that neoantigen+ tumors experience increased T cell infiltration and reduced volume, ultimately leading to prolonged animal survival. Surprisingly, advanced lung tumors maintain neoantigen+ cells, indicating that endogenous lung T cells are ineffective at clearing neoantigen-expressing tumor cells. Yet, we detected that infiltrated tumors exhibit reduced p-ERK expression, suggesting that T cells may slow tumor progression through non-cytotoxic mechanisms. Transferring stimulated neoantigen-specific T cells to tumor-bearing mice largely eliminated neoantigen+ tumor cells. All these data together suggest complex mechanisms for the role of endogenous T cells in controlling lung tumors. Through molecular characterization of tumor progression and T cell-mediated tumor suppression, this study reveals specific pathways that LUAD cells undergo during the process of development and progression, providing valuable insights into the immune response against neoantigen-expressing tumors. Ultimately, by unraveling the intricate interplay between neoantigen expression, immune surveillance, and tumor progression, this project aims to contribute significantly to our understanding of how neoantigens shape the dynamics of tumor biology. Citation Format: Jennifer Loza, Ishan Bansal, Brian Hunt, Kelli Connolly, Srividhya Venkatesan, Advait Jeevanandam, Nikhil Joshi. Exploring the impact of neoantigen expression on lung tumor development [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 3451.