Abstract 3151: β Hydroxy β Methylbutyrate synergizes with cytotoxic chemotherapy and immunotherapy in a mouse model of pancreatic cancer

Abstract

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) remains the 4th most deadly cancer in the US. Current chemotherapeutic regimens poorly control PDAC progression and no approved immunotherapeutic options currently exist. PDAC incidence and progression are increased by obesity, which promotes a potently protumor PDAC microenvironment characterized by inflammation, fibrosis, and immunosuppression. β Hydroxy β Methylbutyrate, found to be safe and well-tolerated in clinical trials over many years, blunts cancer cachexia; however it has not been tested in PDAC. Further, the role of HMB in modifying existing therapies has been understudied. We sought to determine if HMB treatment would alter therapeutic response of lean and obese mice to gemcitabine or anti-PD1 immunotherapy. Methods: Lean and obese C57BL/6 mice were treated with HMB alone or in combination with gemcitabine or anti-PD1 immunotherapy following subcutaneous injection of Panc02 PDAC cells. In addition, bone marrow-derived macrophages (BMDM) were treated with HMB in vitro with or without LPS. Tumor/macrophage transcriptomic analysis, followed by gene set enrichment analysis and enrichment mapping identified transcriptional responses. CIBERSORTx determined microenvironment immune cell composition. Results: a) HMB reduces obesity-associated PDAC progression; b) HMB treatment and gemcitabine together suppress PDAC growth in obese mice; c) HMB mitigates PDAC immunosuppression and promotes tumor immune surveillance; d) HMB enhances the efficacy of anti-PD1 immunotherapy; e) HMB promotes M1 polarization of BMDM. Conclusion: Overall, HMB evokes antitumor immune responses in the context of pro-inflammatory stimuli such as obesity or immunotherapy. Moreover, HMB promotes immune surveillance in PDAC, synergizing with both cytotoxic chemotherapy and immunotherapy. HMB has been found to be safe and well tolerated in clinical trials for many years. Hence, HMB-induced suppression of PDAC tumor growth and promotion of immune surveillance may offer significant synergy with chemotherapies or immunotherapies in PDAC. This research was supported by R35CA197627 to S. Hursting. Citation Format: Michael F. Coleman, Kristyn A. Liu, Suhas K. Etigunta, Alex J. Pfeil, Xiaohu Tang, Salvador Fabela, Laura M. Lashinger, Zhengrong Cui, Stephen D. Hursting. β Hydroxy β Methylbutyrate synergizes with cytotoxic chemotherapy and immunotherapy in a mouse model of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3151.