Abstract 3819: Modeling T cell and cancer cell interactions to examine immune checkpoint inhibition resistance in pancreatic cancer

Abstract Pancreatic cancer (PC) is a lethal cancer, with ∼90% of patients dying within 5 years. This dire statistic underscores the limitations of current treatments and the need for improved therapeutic approaches. Immune checkpoint inhibition (ICI) has shown promise in promoting long-term progression-free survival across various cancers by reactivating a patients’ latent anti-cancer immune response. However, PC is almost completely resistant to ICI, highlighting the incomplete understanding of immune-cancer interactions in this disease. The tumor microenvironment is a key factor in immunotherapy resistance in PC, where immunosuppressive immune cells and cancer-associated fibroblasts (CAFs) act to inhibit T cell function. Additionally, the extracellular matrix (ECM) landscape of PC presents a physical barrier to T cell infiltration and motility within the tumor. Developing strategies to overcome these barriers has been challenging, partly due to the difficulty in replicating the complex PC tumor microenvironment in experimental models. The use of 3D cancer tumoroid cultures enables modeling of cancer and stromal cells spatial arrangements, mimicking native tumor microenvironments and facilitating high resolution examination of cell-to-cell and cell-to-environment interactions. However, most tumoroid cultures often use commercial matrix products like basement membrane extracts (BME), which poorly recapitulate the distinct biochemical and mechanical properties inherent to PC tumors. Here, we utilize the Inventia RASTRUMTM platform to create 3D cancer/CAF/T cell co-cultures based on synthetic PEG-based hydrogel matrices, which were tuned to mimic the stiffness and ECM composition of PC tumors. Using real-time longitudinal imaging and 3D image analysis pipelines, we visualize cancer-stromal cell interactions, which are obscured in conventional BME-based models. We also investigate the role of CAFs in supporting immune evasion and highlight the effect of multiple immunomodulators on cancer/T cell behavioral dynamics. Overall, our approach provides a scalable in vitro framework to dissect cell-to-cell interactions and offers a platform to the profile immunomodulatory properties of drugs. Future work using this platform will focus on molecular profiling of cancer-CAF-T cell interactions to provide predictive data aiding the rational design and evaluation of ICI combination therapies prior to pre-clinical in vivo work and clinical translation. Citation Format: Aji Istadi, Inna Navarro, Silvia Lombardi, Dannielle Upton, Mezzalina Vankan, Cesar Moreno, Michael Trpceski, Cecilia Chambers, David Hermann, Marco Herold, Paul Timpson, Sean Porazinski, Greg Neely, Marina Pajic. Modeling T cell and cancer cell interactions to examine immune checkpoint inhibition resistance in pancreatic cancer [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 3819.