TLR8 agonist 2 is a highly effective and specific compound that activates TLR8, possessing an EC 50 of 3 nM in human TLR8. Notably, TLR8 agonist 2 demonstrates lower activity towards human TLR7, with an EC 50 of 33.33 μM.

TLR8:3 nM (EC50), TLR7:33.33 μM (EC50)

TLR8 agonist 2 (Example 1) enhances the production of TNF-α, IL-12p40, IFN-γ, and IFN-α in human peripheral blood mononuclear cells (hPBMC), with EC50 values of 105 nM, 26 nM, 29 nM, and 2800 nM, respectively[1].

Pharmacokinetic parameters for TLR8 agonist 2 (Example 1) in mice were determined following intravenous (i.v.) administration at 1 mg/kg and oral (p.o.) administration at 5 mg/kg. The half-life (T 1/2) of TLR8 agonist 2 was observed to be 0.25 hours (i.v.) and 0.5 hours (p.o.), with the area under the curve (AUC) last recorded at 450 ng/mL*hr (i.v.) and 624 ng/mL*hr (p.o.). The bioavailability (%F) after oral administration was found to be 27.7%[1].