Abstract 4898: Imipridones and EZH2 inhibitors induce similar changes in cytokines and regulated genes in GBM and DMG while vorinostat potentiates anti-tumor efficacy despite variability in cytokine profiles

Abstract TIC10/ONC201 and ONC206 are small molecule imipridones with anti-cancer activity. ONC201, EZH2i and HDACi can modulate tumor microenvironment (TME) and antitumor immunity. We studied the impact of these drugs or their combinations on the TME or tumor immunity by investigating cytokine profiles. We treated U251 GBM and HCT116 CRC cells with vorinostat and found upregulation of CXCL11, CXCL14, INF-γ and TRAIL, and downregulation of prolactin, CXCL9, VEGF and CCL2 in U251. CXCL11 promotes anti-tumor immunity by increasing activated CD8+ T cells in tumors but was associated with metastasis of GBM. CXCL13 induces tertiary lymphoid structures and enhances infiltration of CD8+ T cells in tumors. INF-γ enhances antigen presentation and promotes activation of NK cells. Vorinostat upregulated the secretion of pro-immune cytokines and TRAIL which induces tumor apoptosis. Downregulated cytokines in U251 were prolactin, CXCL9 involved in tumor growth and metastasis, VEGF, and CCL2 involved in immunosuppression in GBM. Cytokines upregulated in HCT116 included IL-8 contributing to CRC progression, and CXCL13, and CXCL11 which correlates with anti-tumor immunity in colon cancer. Downregulated cytokines in HCT116 were soluble TRAIL R2 functioning as a decoy receptor for TRAIL, VEGF, and prolactin. We treated DMG, GBM and HCC cells with imipridones, EHZ2i tazemetostat or HDACi panobinostat alone or combination of imipridones plus tazemetostat or panobinostat or the triple combination of imipridone plus tazemetostat and panobinostat. We observed that cytokines impairing immunity were downregulated and cytokines promoting immunity were upregulated by individual drugs or combinations. Hep3B HCC cells showed the most robust changes among the mentioned tumors with respect to the changes of cytokine profile following the treatments. Imipridone or EZH2i treated cells showed similar cytokine profile changes in tumor cells. Imipridones downregulated EZH1 and EZH2 proteins in tumor cells. We RNA-seq to investigate gene expression profiles following treatment with ONC201 or tazemetostat. In GBM and DMG, ONC201 and tazemetostat shared similar top regulated genes. GO enrichment analysis showed overlap of top regulated pathways between ONC201 and EZH2i treated cells. Shared regulated pathways in U251 included cell cycle arrest, cell adhesion, nervous system development, cell proliferation, negative regulation of proliferation, PERK-mediated unfolded protein response, extracellular matrix organization, regulation of transcription from RNA polymerase II promoter, and cellular response to hypoxia pathways. We conclude that imipridones ONC201, ONC206, and ONC212 which reduce EZH1 and EZH2 proteins share similar cytokine alterations, gene expression targets and actions with EZH2 inhibitors. Citation Format: Yiqun Zhang, Kelsey Huntington, Wafik S. El-Deiry. Imipridones and EZH2 inhibitors induce similar changes in cytokines and regulated genes in GBM and DMG while vorinostat potentiates anti-tumor efficacy despite variability in cytokine profiles. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4898.