SAR-20347 is an inhibitor of TYK2, JAK1/2/3 (IC50: 0.6/23/26/41 nM).

SAR-20347 effectively inhibits IL-12-mediated STAT4 phosphorylation (TYK2-dependent, IC50: 126 nM) when NK-92 cells are stimulated with IL-12. In the culture media, cells without IL-12 have no measurable IFN-γ, while cells incubated with IL-12 and SAR-20347 demonstrate dose-dependent inhibition of IFN-γ production. SAR-20347 (maximum effect: 5 μM) dose-dependently inhibits the production of secreted embryonic alkaline phosphatase (SEAP).

Compared to vehicle-treated animals, SAR-20347 (60 mg/kg) inhibits the production of IFN-γ in the serum by 91%, demonstrating that SAR-20347 can inhibit TYK2 signaling in vivo. SAR-20347 markedly reduces IL-17 production as measured by average signal intensity, consistent with the gene expression analysis.

Kinases are prepared in Base Reaction Buffer (20 mM Hepes pH 7.5, 10 mM MgCl2, 1 mM EGTA, 0.02% Brij35, 0.02 mg/mL BSA, 0.1 mM Na3VO4, 2 mM DTT, 1% DMSO) and substrate is added with 1.5 mM CaCl2, 16 μg/mL Calmodulin, and 2 mM MnCl2. Varying concentrations of SAR-20347 in DMSO are added to the kinase reaction along with 10 μM 33P-ATP (activity 0.01 μCi/μL final) for IC50 determination[1].

Cells are plated in a 96-well v-bottom plate in starvation medium, incubated with SAR-20347 (0.5% DMSO) for 20 minutes at 37°C, 5% CO2, and stimulated with individual cytokines. P-STAT levels are measured in duplicate using MSD plates following the manufacturer's instructions (MSD)[1].

Female 7 to 9-week old C57BL/6 mice are used. Mice are administered vehicle or 50 mg/kg SAR-20347 by oral gavage 30 minutes prior to application of 62.5 mg 5% imiquimod cream or control cream. Another dose of vehicle or 50 mg/kg SAR-20347 is given 5.5 hours following the first dose. This treatment is repeated for 5 days and on day 3 and 4, animals are injected with 100 uL saline to prevent dehydration. On the 6th day, the animals are euthanized and photographs are taken[1].