BRD6989 is an inhibitor of cyclin-dependent kinase 8 (CDK8) that upregulates production of interleukin-10 (IL-10). BRD6989 was shown to bind cyclin C–CDK8 complex selectively with an IC50 value ~200 nM and to inhibit the kinase activity of recombinant cyclin C–CDK8 or cyclin C–CDK19 complexes with IC50 values ~500 nM and >30 µM, respectively. It enhanced the production interleukin-10 (IL-10) enhances IL-10 production in activated human and murine macrophages and dendritic cells with an EC50 value ~1 µM.