Abstract C036: Cancer associated fibroblasts are regulators of the tumor microenvironment in human pancreatic ductal adenocarcinoma

Abstract Introduction: Pancreatic ductal adenocarcinoma (PDAC) is a classically heterogeneous tumor for which tumor cells comprise less than 40% of the total tumor mass. To better understand mechanisms of intercellular interactions driving tumor response or resistance to chemotherapy, it is crucial to account for the complex tumor microenvironment (TME). Specifically, cancer associated fibroblasts (CAFs) have been implicated as both a tumor promoting and tumor restraining entity through disease progression and have therefore been a focus of our evolving model system. Methods: Our group created a 3-dimensional (3D), matched coculture system of patient-derived organoids (PDO), CAFs, and immune cells obtained from patients undergoing surgical resection. PDOs grown in 3D preserves the nascent tumor architecture and better replicates the disease in vitro than traditional 2D cell lines. The fully patient-matched coculture model of human PDAC allows for mechanistic interrogation into the PDAC TME by utilizing multiparameter flow cytometry, cellular sorting, and qPCR. Additionally, pharmacotyping experiments using a 5-drug regimen were used to assess chemotherapeutic resistance allowing for targeted questions exploring patient response to standard of care chemotherapy. Results: Using a combination of direct CAF-PDO coculture and PDO with CAF-conditioned media, we examined the direct (coculture) and indirect (conditioned media) impact of CAFs on PDOs. Using flow cytometry, we showed that CAF-conditioned human complete organoid media drives increased proliferation of PDOs when compared to PDOs grown in standard media. This effect was likely due to factors that are secreted from CAFs having a synergistic effect with compounds in the human complete organoid media, as this phenotype was not replicated in traditional serum free conditioned media. In direct coculture experiments of PDOs and CAFs, PDO numbers increased over time from day 2 to day 7 when compared to monoculture of PDOs, likely due to CAF presence. Lastly, to explore how CAFs may alter chemotherapeutic efficacy, PDOs were cocultured with CAFs and assessed for chemotherapeutic resistance. Pharmacotyping results showed that PDOs sorted from the PDO-CAF coculture exhibited a change in IC50 value in comparison to those PDOs that were not cocultured with CAFs. Conclusions: Here we put forth a model of PDO and CAF coculture and demonstrated its application for examining the impact of CAFs on PDAC proliferation and chemotherapeutic response. These data demonstrate the feasibility of establishing a patient-derived matched coculture model and provide the backbone for expanding this model to include representative immune cells. Citation Format: Samantha Guinn, Joseph Tandurella, Jacquelyn Zimmerman, Richard Burkhart, Elizabeth M. Jaffee. Cancer associated fibroblasts are regulators of the tumor microenvironment in human pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C036.