SEL120 (SEL120-34A) hydrochloride

SEL120-34A inhibits kinase activities of CDK8/CycC and CDK19/CycC complexes with an IC50 of 4.4 nM and 10.4 nM, respectively. It does not significantly inhibit other members of the CDK family in a single point inhibition assay, namely CDK1, 2, 4, 6, 5, 7 in vitro, with the exception of CDK9, however a calculated IC50 1070 nM, indicated an over 200 fold selectivity against this kinase. SEL120-34A inhibits phosphorylation of STAT1 S727 and STAT5 S726 in cancer cells, inhibits mitogen- induced expression of immediate early response (IER) genes and IFN- responsive genes expression in vitro^[1]. In a broad panel of cancer cell lines, the compound shows the strongest activity in hematological malignancies, especially in selected acute myeloid leukemia (AML) (GI50 12 nM), acute lymphoblastic leukemia (ALL) and mantle cell lymphoma (MCL) models. SEL120−34A could alter transcriptional programs linked to differentiation of leukemia cells^[2].

HCT-116 are seeded onto 6-well plates at 2.5×10⁵/well. On the following day, cells are synchronized for 24 h by 0.5% FBS starvation, pretreated with 0.1% DMSO or SEL120-34A at the indicated concentration for 1 h and then supplemented with either 10% FBS, IFNg or IFNa in the presence of the inhibitor (4h). Cells are centrifuged at 1300 rpm for 5 min at 4°C, washed once with 1 ml of ice-cold PBS and stored at -80°C.

SEL120-34A has favorable pharmacodynamics to be sufficient to affect expression of CDK8 and CDK19- dependent genes in vivo. SEL120-34A treatment causes specific alterations in interferon- responsive genes and inhibits the proliferation of AML cell lines in vivo. SEL120-34A does not affect normal hematopoiesis^[1]. SEL120−34A effectively inhibits tumor growth in subcutaneous responder AML and MCL models when administered orally^[2].