Abstract C019: FAK suppresses antigen processing and presentation to promote immune evasion in pancreatic cancer

Abstract

Abstract Immunotherapy for the treatment of Pancreatic Ductal Adenocarcinoma (PDAC) has shown limited efficacy. Poor CD8 T-cell infiltration, low neoantigen load and a highly immunosuppressive tumor microenvironment are key factors that contribute to this lack of response. Here, we identify a novel role for Focal Adhesion Kinase (FAK) in regulating type-II interferon signalling in human and murine PDAC cells and tumors, leading to suppression of antigen processing and presentation pathways critical for T-cell tumor recognition. We find that FAK loss promotes expression of the immunoproteasome and MHC-I, resulting in a significant increase in the diversity of antigens presented by FAK-/- PDAC cells. We show that regulation of the immunoproteasome subunit Psmb8 (β5i) is a critical determinant of this response, optimising the physicochemical properties of the peptide repertoire for high-affinity binding to MHC-I. Expression of the immunoproteasome and MHC-I can be further amplified in a STAT1-dependent manner via co-depletion of FAK and STAT3, leading to extensive CD8 T-cell infiltration into PDAC tumors and further restraint of tumor growth. Regulation of antigen processing and presentation by FAK preferentially occurs in human and murine PDAC cells and tumors of the classical/progenitor molecular subtype, further suggesting that precision medicine approaches based on molecular subtyping should be integrated into current and future clinical testing of FAK targeted therapies for the treatment of pancreatic cancer. Citation Format: Marta Canel, Aleksandra Slawinska, David W. Lonergan, Ashwin A. Kallor, Rosie Upstill-Goddard, Catherine Davidson, Alex von Kriegsheim, Andrew V. Biankin, Adam Bryron, Javier Alfaro, Alan Serrels. FAK suppresses antigen processing and presentation to promote immune evasion in pancreatic cancer [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 C019.