Discovery of D2469079A, A novel selective Toll-Like Receptor 7/8 Antagonist with Brain Penetrance

Aberrant activation of endosomal Toll-like receptors (TLRs) 7 and 8, which recognize single-stranded RNA, is strongly implicated in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE). And the frequent neuropsychiatric involvement in SLE highlights the need for brain-penetrant therapies. Here, we report the identification and characterization of D2469079A, a novel, potent dual TLR7/TLR8 antagonist (low nM IC ₅₀ in humanized HEK-Blue assays) selective against hTLR9. D2469079A demonstrates favorable in vitro properties, including adequate solubility and high microsomal stability. It exhibited desirable pharmacokinetic profiles across multiple preclinical species (mice, rats, dogs) and achieved significant cerebrospinal fluid (CSF) exposure, confirming its high permeability and brain penetration. Consistent in vivo efficacy was observed in both acute and chronic stimulation models. Importantly, D2469079A displayed a favorable safety profile, lacking significant liabilities related to CYP450 inhibition/induction, hERG interaction, or toxicity in a 14-day rat study. These findings position D2469079A as a promising drug candidate with excellent drug-like characteristics for the treatment of TLR7/8-driven autoimmune diseases, potentially including neuropsychiatric manifestations. We are actively seeking partners for collaborative clinical development.