Abstract 5548: Cannabidiol enhances efficacy of atezolizumab via upregulation of PD-L1 expression by cGAS-STING pathway in triple negative breast cancer cells

Abstract

Abstract The current treatment for patients with triple negative breast cancer (TNBC) relies on cytotoxic therapy. Currently, atezolizumab and chemotherapy can be combined in patients with TNBC, but this approach is not effective for all patients with low reactivity to atezolizumab. As there is a lack of alternative treatment options, new anti-cancer drugs are urgently needed to enhance atezolizumab reactivity against TNBC. Recent strategies have focused on regulating the expression of programmed death-ligand 1 (PD-L1) or enhancing immune response activation by combining anti-cancer drugs with immune checkpoint inhibitors (ICIs). Cannabidiol (CBD), a cannabinoid component derived from the cannabis plant, has been reported to have anti-cancer therapeutic potential because of its capacity to induce apoptotic cell death in tumor cells while avoiding cytotoxicity in normal cells. Previous studies have demonstrated the effects of CBD on apoptosis in various types of cancer cells. However, the potential role of CBD as an immune modulator in the regulation of PD-L1 expression and the anti-cancer immune response remains to be explored. In this study, we found that CBD stimulated PD-L1 expression in TNBC cells, which significantly induced CBD-mediated cGAS-STING pathway activation. Taken together, we demonstrated that the combination of CBD and anti-PD-L1 antibody enhances the anti-cancer immune response in vitro and in vivo experiments. Our findings identified the mechanism of PD-L1 regulation by CBD in TNBC cells and suggested that CBD could be a potential candidate for the development of new combinatorial strategies with ICIs in TNBC patients. Citation Format: Bu Gyeom Kim, Bo Ram Kim, Dae Yeong Kim, Hyemi Yun, Dayoung Kim, Woo Young Kim, Sanghee Kang, Sun Il Lee, Sang Cheul Oh. Cannabidiol enhances efficacy of atezolizumab via upregulation of PD-L1 expression by cGAS-STING pathway in triple negative breast cancer cells [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 5548.