Discovery of GS-9688 (Selgantolimod) as a Potent and Selective Oral Toll-Like Receptor 8 Agonist for the Treatment of Chronic Hepatitis B.

Journal of medicinal chemistry 2020 Sep 24

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Toll-like receptor 8 (TLR8) recognizes pathogen-derived single-stranded RNA fragments to trigger innate and adaptive immune responses. Chronic hepatitis B (CHB) is associated with a dysfunctional immune response, and therefore a selective TLR8 agonist may be an effective treatment option. Structure-based optimization of a dual TLR7/8 agonist led to the identification of the selective TLR8 clinical candidate (R)-2-((2-amino-7-fluoropyrido[3,2-d]pyrimidin-4-yl)amino)-2-methylhexan-1-ol (GS-9688, (R)-7). Potent TLR8 agonism (IL-12p40 EC50 = 220 nM) and >100-fold TLR7 selectivity (IFN-α EC50 > 50 μM) was observed in human peripheral blood mononuclear cells (PBMCs). The TLR8-ectodomain:(R)-7 complex confirmed TLR8 binding and a direct ligand interaction with TLR8 residue Asp545. Oral (R)-7 had good absorption and high first pass clearance in preclinical species. A reduction in viral markers was observed in HBV-infected primary human hepatocytes treated with media from PBMCs stimulated with (R)-7, supporting the clinical development of (R)-7 for the treatment of CHB.

Citation

Richard L Mackman, Michael Mish, Gregory Chin, Jason K Perry, Todd Appleby, Vangelis Aktoudianakis, Sammy Metobo, Peter Pyun, Congrong Niu, Stephane Daffis, Helen Yu, Jim Zheng, Armando G Villasenor, Jeff Zablocki, Jason Chamberlain, Haolun Jin, Gary Lee, Kimberley Suekawa-Pirrone, Rex Santos, William E Delaney, Simon P Fletcher. Discovery of GS-9688 (Selgantolimod) as a Potent and Selective Oral Toll-Like Receptor 8 Agonist for the Treatment of Chronic Hepatitis B. Journal of medicinal chemistry. 2020 Sep 24;63(18):10188-10203