Abstract 2585: Targeted protein upregulation strategy potentiates STING agonist immunotherapy

Abstract As cancer immunotherapy has been emerged as a new pillar of cancer therapy, many strategies modulating host immunity were suggested for cancer treatment. Stimulator of interferon genes (STING) is a promising target for anticancer immunotherapy. However, dysregulated STING expression, or poor pharmacokinetic profiles of STING agonists pose major challenges. Recently, modulating target protein levels via the ubiquitin-proteasome system, such as proteolysis-targeting chimera (PROTAC), has broadened the scope of pharmacological inventions. Herein, we propose UPPRIS (upregulation of target proteins by protein-protein interaction strategy) to overcome these limitations. We discovered the small molecule SB24011 that inhibits STING-E3 ligase interaction, thereby induces the blockade of E3 ligase-mediated STING degradation. As a result, SB24011 enhanced the STING agonist-mediated immune responses by upregulating cellular STING protein level. Thus, co-administration of SB24011 markedly improved the immuno-oncological efficacy of STING agonist cGAMP and anti-PD-1 therapy for tumor regression and robust systemic antitumor response. Taken together, we successfully demonstrated that targeted STING protein upregulation is a promising strategy for cancer immunotherapy. Citation Format: Wansang Cho, Solchan Won, Yoona Choi, Jong Beom Park, Jun-Gyu Park, Sihyeong Yi, Caroline E. Kim, Chintam Narayana, Dong-Sup Lee, Seung Bum Park. Targeted protein upregulation strategy potentiates STING agonist immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2585.