Enpatoran is an inhibitor of TLR7(IC50 = 11.1 nM) and TLR8(IC50 = 24.1 nM). Enpatoran was found to be inactive against TLR3, TLR4, and TLR9 in vitro and in vivo.

TLR7:68.3 nM (in peripheral blood mononuclear cells (PBMCs)), TLR7:2.2 nM (in whole blood (WB) cells), TLR8:620 nM (in peripheral blood mononuclear cells (PBMCs)), TLR8:24.1 nM, TLR8:120 nM (in whole blood (WB) cells), TLR7:11.1 nM

Enpatoran inhibited activity against different TLRs in a variety of cellular systems. Enpatoran potently inhibited TLR7 and TLR8 in HEK NF-κB-luciferase reporter cells with IC50 values in the low nanomolar range. Additionally, Enpatoran was found to be potent against TLR7 and TLR8 in PBMCs as well as whole blood. There appears to be an increased selectivity for TLR7 inhibition relative to TLR8 for Enpatoran in whole blood compared with PBMCs and transfected HEK cells[1].

In the BXSB-Yaa model, there is a robust increase in multiple autoantibodies, and Enpatoran significantly reduced both DNA-containing reactivities such as anti-dsDNA and anti-histones, as well as RNA-binding protein reactivities such as anti-RiboP and anti-SmRNP. At high dosages of Enpatoran, the effect on autoantibodies is so profound that titers are reduced below the baseline levels[1].