Abstract B050: Patient-matched EUS-FNB-derived organoid-CAF co-culture platform reveals novel resistance mechanisms in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) exhibits profound treatment resistance attributed to complex tumor-stroma interactions within the desmoplastic microenvironment. Cancer-associated fibroblasts (CAFs) play critical roles in chemoresistance, yet current drug screening models predominantly utilize single organoid systems that fail to recapitulate authentic tumor-stroma crosstalk. We established patient-matched organoid-CAF co-culture systems from endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) specimens. Primary organoids and CAFs were isolated from identical patient samples, with drug sensitivity assays comparing monoculture versus co-culture responses. CAF characterization employed flow cytometry analysis of alpha-smooth muscle actin, fibroblast activation protein, and vimentin, while multiplex cytokine profiling characterized secretory networks. Single-cell RNA sequencing and expanded functional validation studies are ongoing. Co-culture dramatically altered chemosensitivity profiles compared to organoid monoculture, revealing tumor-stroma interactions driving therapeutic resistance. Importantly, we discovered distinct patient-specific cytokine resistance profiles. Some patients exhibited tumor necrosis factor-alpha-centered resistance mechanisms, while others displayed interleukin-8 or interleukin-6-mediated inflammatory response patterns. These patient-specific cytokine networks correlated with unique resistance patterns, suggesting individualized secretory circuits mediating treatment failure. Three-way comparative analysis demonstrated emergent interactive responses exceeding additive effects, while flow cytometry revealed remarkable patient-specific heterogeneity in CAF activation marker expression. This study establishes a clinically-relevant platform that recapitulates patient-specific tumor-stroma interaction patterns in pancreatic cancer. Identification of patient-specific cytokine resistance signatures provides therapeutic targets for individualized combination therapy strategies. Ongoing single-cell transcriptomics and expanded molecular profiling will further define stromal subtypes and resistance signatures, advancing precision medicine-based therapeutic development that considers patient-specific resistance mechanism heterogeneity in pancreatic cancer. Citation Format: Kyung Min Lee, Yooyeon Kim, Eunhye Hwang, Jin Ho Choi, Woo Hyun Paik, , Sang Hyub Lee. Patient-matched EUS-FNB-derived organoid-CAF co-culture platform reveals novel resistance mechanisms in pancreatic cancer abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research—Emerging Science Driving Transformative Solutions; Boston, MA; 2025 Sep 28-Oct 1; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2025;85 (18Suppl₃): Abstract nr B050.