Abstract B042: The impact of opioids on the pancreatic tumor immune microenvironment

Abstract

Abstract Pancreatic cancer is a highly lethal malignancy with a 5-year survival rate of 12.8%. Due to the high prevalence of cancer-related pain, 75% of pancreatic cancer patients are prescribed opioids. Opioids, which signal through the G protein-coupled receptor (GPCR) mu-opioid receptor (MOR), have peripheral effects outside of their analgesic function. Importantly, several studies have correlated opioids with worsened survival of patients receiving immunotherapy. However, the mechanism behind this is unknown. Immunotherapy is largely ineffective in pancreatic cancer, due in part to the tumor microenvironment (TME) characterized by dense, desmoplastic stroma, with cancer-associated fibroblasts (CAFs) comprising up to 90% of the tumor volume. CAFs play a large role in immunosuppression and therapy resistance, such as through promoting infiltration of immunosuppressive cells, resulting in reduced presence of antitumor immune cells and impaired immunotherapy efficacy. While the role of CAFs in promoting immunosuppression in the tumor microenvironment is well characterized, the effect of opioids on this phenomenon is unknown. We now provide evidence that MOR directly regulates CAF function. Specifically, knockdown of MOR in CAFs reduces gene expression of alpha-smooth muscle actin (aSMA) and leukemia inhibitory factor. MOR knockdown in CAFs also decreases protein expression of aSMA and type 1a collagen. We hypothesize that opioids promote MOR-dependent CAF activation and secretion of pro-inflammatory cytokines, resulting in a more immunosuppressive TME, and thus impaired immunotherapy response. The long-term goal of this work is to determine the role of opioids on CAFs in the pancreatic TME, as well as the role of MOR in promoting immunosuppression and the resulting value of MOR as a target to improve immunotherapy efficacy. This research is clinically significant because it could uncover a novel mechanism driving immunosuppression caused by a medication commonly prescribed to almost all pancreatic cancer patients. Citation Format: Kathryn Maraszek, Michael Feigin. The impact of opioids on the pancreatic tumor immune microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B042.