Abstract 1831: Reduction of PMN-MDSC level/activity following the consumption of white button mushroom in prostate cancer murine models and patients: A translational study to mitigate cancer progression

Abstract

Abstract Frequent consumption of edible mushrooms, such as white button mushrooms (WBM), has been associated with a lower risk of prostate cancer [1]. Our laboratory at City of Hope has over 20 years of collective experience in defining the anticancer mechanisms of WBM [2, 3]. Previous studies have indicated that WBM consumption has anti-androgenic activities in prostate cancers in both preclinical models [4] and clinical trials [5]. In our first-in-human phase 1 trial on prostate cancer patients, we ensured the safety of consuming WBM in humans. In addition to observing a therapeutic-responsive decline in prostate-specific antigen (PSA), the levels of myeloid-derived suppressor cells (MDSCs) reduced in responders to WBM treatments [5]. These observations led us to hypothesize that WBM may mitigate the progression of prostate cancer in part by modulating the immune response. In the current study, we conducted translational research in syngeneic murine models and in prostate cancer patients from an ongoing phase 2 trial, aiming to define the immunomodulatory activity and mechanisms of WBM. We confirmed that WBM consumption in mouse models altered the number and function of immunosuppressive cells (MDSCs) and anti-tumor immune cells (T & NK cells), ultimately enhancing the intratumor and systemic immune responses. At a bulk-transcriptional level, we observed the elevated expression of programmed cell death protein 1 (PD-1) in xenograft tumors. In our single immune cell profiling of patients’ blood specimens following 3 months of WBM consumption in freeze-dried tablets form, we investigated the transcriptional landscape of circulating immune cells in response to WBM interventions. The level of circulating neutrophil-associated PMN-MDSCs decreased, and the remaining cells showed transcriptional profiles associated with "neutrophil chemotaxis", "leukocyte aggregation", and "regulation of inflammatory response", as functions associated with enhanced anti-tumor activity. Lastly, we also showed in a mouse model that WBM consumption synergistically enhances the anticancer activity of anti-PD1 drugs, indicating that WBM may be used as adjuvant therapy with immune checkpoint inhibitors. In summary, our results from prostate cancer patients and murine models show the immunomodulatory effects of WBM consumption and provide a scientific foundation for the application of WBM in alleviating prostate cancer progression. References 1, Zhang S., et al. Int. J. Cancer. 2019; 146:2712-2720. 2, Chen S., et al. Cancer Res. 2006; 66:12026-12034. 3, Adams L.S., et al. Nutr. Cancer. 2008; 60:744-756. 4, Wang X., et al. J. Nutr. Biochem. 2021; 89:108580.5, Twardowski P., et al. Cancer. 2015; 121:2942-2950. Citation Format: Xiaoqiang Wang, Shoubao Ma, Przemyslaw Twardowski, Clayton Lau, Yin Chan, Kelly Wong, Jinhui Wang, Xiwei Wu, Paul Frankel, Timothy G. Wilson, Timothy W. Synold, Cary Presant, Jianhua Yu, Shiuan Chen. Reduction of PMN-MDSC level/activity following the consumption of white button mushroom in prostate cancer murine models and patients: A translational study to mitigate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1831.