Development of Orally Bioavailable Amidobenzimidazole Analogues Targeting Stimulator of Interferon Gene (STING) Receptor

Stimulator of interferon gene (STING) is a critical adaptor protein that has a pivotal role in triggering inherent immune responses to infection. STING-linked interferon production has been involved in anti-inflammation, anti-infection, and antitumor immunity. Herein, a series of amidobenzimidazole analogues as STING agonists were profiled for potency and drug-like properties. By structure-based modification and optimization based on mono-aminobenzimidazole (ABZI), analogues with nanomolar STING agonistic activities were obtained. Among them, compounds D59 and D61 significantly increased the transcription of IFN-β and proinflammatory cytokine CXCL10, as well as dramatically induced the phosphorylation of STING downstream proteins in THP1 cells. Furthermore, compound D61 exhibited favorable pharmacokinetic properties and metabolic stabilities. In a CT-26 syngeneic mice-bearing tumor model, D61 effectively inhibited tumor growth with good tolerance when administered via intratumoral, intravenous, intraperitoneal, and oral routes. This research on orally bioavailable amidobenzimidazole analogues expands the diversity of chemical structures of agonists for STING-mediated immunotherapy.