S18-000003 is a potent, selective and orally active inhibitor of retinoic acid receptor-related orphan receptor-gamma-t (RORγt), with an IC50 of 10 μM). S18-000003 can be used for the research of psoriasis with low risk of thymic aberrations[1][2].

S18-000003 inhibits human and mouse RORγt-dependent transactivation, with IC50s of 0.029 and 0.34 μM respectively in cell-based GAL4 promoter reporter assays[1].S18-000003 (0.003-0.3 μM; 7 d) dose-dependently inhibits Th17 cell differentiation from human naive CD4+T cells, with an IC50 of 0.024 μM[2]. S18-000003 (0.1-3 μM; 4 d) inhibits the differentiation of mouse Th17 cells from splenic naive CD4+T cells, with an IC50 of 0.20 μM[2].S18-000003 (0.03-1 μM; 3 d) reduces the IL-17 production in human PBMCs in a dose-dependent manner, and does not inhibit either the production of other cytokines (IL-2, IL-4, IL-10 and IFN-g) or cell proliferation[2].S18-000003 (0.1-3 μM; 3 d) reduces IL-17 and IL-22 production in PBMCs from psoriatic mice in a dose-dependent manner[2].

S18-000003 (30-100 mg/kg; p.o.) inhibits IL-17 production in the skin of IL-23-treated mice in a dose-dependent manner[1].S18-000003 (0.1-8%; 100mL; topically administration once daily for 14 days) ameliorates psoriasis-like lesions in TPA-induced K14.Stat3C transgenic mice, and has little impact on the thymus[2].S18-000003 (0.5 mg/kg; i.v.) exhibits the half-life (3.2 h), AUC (1930 ng•h/mL), CLtot (4.33 mL/min/kg) and Vdss in rats[1].S18-000003 (1 mg/kg; p.o.) exhibits the oral bioavailability (54.5%), Cmax (185 ng/mL), AUC (2110 ng•h/mL) and Tmax (4 h) in rats[1].

[1]. Sasaki Y, et, al. Discovery of a potent orally bioavailable retinoic acid receptor-related orphan receptor-gamma-t (RORγt) inhibitor, S18-000003. Bioorg Med Chem Lett. 2018 Dec 1;28(22):3549-3553.
[2]. Imura C, et, al. A novel RORγt inhibitor is a potential therapeutic agent for the topical treatment of psoriasis with low risk of thymic aberrations. J Dermatol Sci. 2019 Mar;93(3):176-185.