Antagonism of the Toll-like receptors (TLRs) 7 and TLR8 has been hypothesized to be beneficial to patients suffering from autoimmune conditions. A phenotypic screen for small molecule antagonists of TLR7/8 was carried out in a murine P4H1 cell line. Compound 1 was identified as a hit that showed antagonistic activity on TLR7 and TLR8 but not TLR9, as shown on human peripheral blood mononuclear cells (hPBMCs). It was functionally cross reactive with mouse TLR7 but lacked oral exposure and had only modest potency. Chemical optimization resulted in 2, which showed in vivo efficacy following intraperitoneal administration. Further optimization resulted in 8 which had excellent in vitro activity, exposure and in vivo activity. Additional work to improve physical properties resulted in 15, an advanced lead that had favorable in vitro and exposure properties. It was further demonstrated that activity of the series tracked with binding to the extracellular domain of TLR7 implicating that the target of this series are endosomal TLRs rather than downstream signaling pathways.

已经假设Toll样受体（TLRs）7和TLR8的拮抗作用对患有自身免疫病的患者是有益的。在鼠P4H1细胞系中进行了TLR7 / 8小分子拮抗剂的表型筛选。如人类外周血单核细胞（hPBMCs）所示，化合物1被确定为对TLR7和TLR8表现出拮抗活性但对TLR9没有拮抗作用的命中。它在功能上与小鼠TLR7有交叉反应，但缺乏口服暴露，且效力适中。化学优化产生2，其在腹膜内给药后显示出体内功效。进一步优化后得到8个，它们具有出色的体外活性，暴露能力和体内活性。改善物理特性的其他工作产生了15种先进的铅，具有良好的体外和暴露特性。进一步证明，该系列的活性随与TLR7的胞外域的结合而被追踪，这暗示该系列的靶标是内体TLR而不是下游信号传导途径。