Abstract A063: Inhibition of TREX1 increases type I interferon signaling and reduces tumor growth in vivo

Abstract TREX1 exonuclease prevents cytosolic DNA-driven cell-intrinsic IFN response and subsequent inflammation and immune activation. Indeed, TREX1 induction in cancer cells has been shown to inhibit the IFN response and dampen antitumor immunity, suggesting TREX1 as a promising target for cancer therapy. Sprint Bioscience develops small-molecule drugs by using a fragment- and structure-based approach. Diverse projects focused on oncology, including TREX1, are developed in parallel using Sprint Bioscience's multidisciplinary drug development platform. We have developed small-molecule TREX1 inhibitors (TREX1i) with sub-nanomolar biochemical potency and high selectivity. Using a reporter cell line to monitor IRF activation, we show low nanomolar cellular potency of the inhibitors. We also demonstrate that in the colon cancer HCT116 cells, our leading TREX1i induces innate immune signaling pathways at protein levels such as phospho-TBK1 and STAT1. Moreover, in the CT26 syngeneic mouse model, the front-runner TREX1i significantly reduces tumor growth and increases immune cell infiltration measured by flow cytometry. Unbiased Nanostring IO 360 panel analysis performed in vehicle and TREX1i-treated CT26 tumors showed that pharmacological TREX1 inhibition is associated with the induction of multiple IFN-stimulated genes (ISGs), antigen processing & presentation machinery (APP) genes (such as TAP1, B2M, and HLA genes), and STING-TBK1-IRF3-induced chemokines (such as CCL5 & CXCL-10). In conclusion, our data using pharmacological TREX1 inhibition support recent publications reporting the anti-tumor immunity effects linked to genetic TREX1 inhibition in vivo and indicate that TREX1i have promising potential for use as a therapeutic intervention in oncology. Citation Format: Madhurendra Singh, Camilla Silvander, Madeleine Livendahl, Ritu Bansal, Anton Gripenberg, Lionel Trésaugues, Wimal Ubhayasekera, Adrian Romero, Weihua Ye, Johan Lindstrom, Simon Moussaud, Angelo De Milito, Martin Andersson. Inhibition of TREX1 increases type I interferon signaling and reduces tumor growth in vivo [abstract]. In: Proceedings of the AACR IO Conference: Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2025 Feb 23-26; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(2 Suppl):Abstract nr A063.