TLR8 agonist 2 hydrochloride is a highly potent and selective agonist for human TLR8, exhibiting an EC50 of 3 nM. However, its activity towards human TLR7 is considerably weaker, with an EC50 of 33.33 μM.

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

TLR8 agonist 2 (Example 1) increases the levels of TNF-α, IL-12p40, IFN-γ, and IFN-α with EC 50 values 105 nM, 26 nM, 29 nM, and 2800 nM, respectively, in human peripheral blood mononuclear cells (hPBMC)[1].

The pharmacokinetic related parameters of TLR8 agonist 2 (Example 1) in mice administered with the intravenous administration of 1 mg/kg and the oral administration of 5 mg/kg are detected. The T 1/2 of TLR8 agonist 2 are 0.25 h (1 mg/kg i.v.) and 0.5 h (5 mg/kg p.o.), the AUC last are 450 ng/mL*hr (i.v.) and 624 ng/mL*hr (p.o.). And for oral administration, the bioavailability (%F) is 27.7%[1]