Halogen-methyl hybridization unlocks orally bioavailable STING agonist for tumor immunotherapy

The activation of the stimulator of interferon genes (STING) represents a pivotal strategy in tumor immunotherapy. Currently, there is a pressing need for more small-molecule STING agonists to advance into clinical trials. In this study, we developed a series of benzofuran derivatives as novel non-nucleotide STING agonists through structure-based drug design strategies. Systematic optimization yielded the candidate compound X41, which exhibits potent STING agonist activity and favorable drug-like properties. Structural refinement was achieved through R³-position ''chloro'' (Cl) and R¹-position ''methyl effect'' (CH₃) substituents, optimizing the balance between target potency and membrane permeability. Mechanistic characterization revealed that X41 demonstrates dose-dependent activation of the STING signaling pathway in THP1-Dual cells, significantly inducing downstream IFN-β and CXCL10 expression. In the MC38 syngeneic tumor model, oral administration of X41 (50 mg/kg) achieved substantial tumor growth inhibition (TGI = 88.04 %), while intraperitoneal dosing (20 mg/kg) induced complete tumor regression in 50 % of the treated mice. Pharmacokinetic profiling demonstrated favorable plasma exposure and metabolic stability, with an oral half-life (T_1/2) of 9.92 h. These integrated preclinical studies establish X41 as a structurally novel oral STING agonist with significant translational potential, positioning it as a promising candidate for the immunotherapy of solid tumors.