(S)-(2-(4-chlorophenyl)pyrrolidin-1-yl)(3-methyl-1H-pyrazolo[3,4-b]pyridin-5-yl)methanone

MSC2530818 is an orally bioavailable cyclin-dependent kinase 8 (Cdk8) inhibitor (IC₅₀ = 2.6 nM). It is selective for Cdk8 over a panel of 264 kinases at 1 μM but does inhibit glycogen synthase kinase 3α (GSK3α; IC₅₀ = 691 nM). MSC2530818 inhibits STAT1 phosphorylation in SW620 colorectal cancer cells with an IC₅₀ value of 8 nM. It also inhibits Wnt-dependent transcription in LS 174T, COLO 205, and PA-1 cancer cells (IC₅₀s = 32, 9, and 52 nM, respectively, in luciferase reporter assays). MSC2530818 (50 and 100 mg/kg) reduces tumor growth in a SW620 mouse xenograft model.