Inhibition Of Cdk8 Kinase With Sel120-34a Allows For A Personalized Approach In Aml

Inhibition of oncogenic transcriptional programs is recognized to be a promising therapeutic strategy. SEL120-34A is a novel inhibitor of Cyclin- dependent kinase 8 (CDK8), which regulates transcription by associating with the Mediator complex. SEL120-34A interacts with the ATP binding site of CDK8 in type I inhibitor fashion and forms several types of interactions, including halogen bonds with the protein’s hinge region and hydrophobic complementarities within its front pocket. Although the compound was only modestly active in solid tumor cell lines, it repressed phosphorylation of STAT5 Ser726 and could differentially inhibit viability of AML and ALL cell lines in vitro and in vivo, along with other type I CDK8 inhibitors. Transcriptomic analysis identified major transcriptional programs altered in responder cell lines, which strongly indicated that apart from repression of survival pathways, CDK8 inhibitors could induce differentiation in cell lines with leukemia stem cells characteristics. Further studies on a large panels of responder and non-responder cell lines identified robust biomarkers which could be used with high confidence for stratification and personalized approach in CDK8-dependent AML cases. Favorable pharmacokinetics, confirmed safety and in vivo efficacy in leukemia models provide the rationale for further clinical development of SEL120-34A. Citation Format: Tomasz Rzymski, Michal Mikula, Eliza Zylkiewicz, Agnieszka Dreas, Katarzyna Wiklik, Aniela Golas, Katarzyna Wojcik, Magdalena Masiejczyk, Iga Dudzicz, Katarzyna Kucwaj, Malgorzata Statkiewicz, Krzysztof Goryca, Aleksandra Grochowska, Aleksandra Cabaj, Jerzy Ostrowski, Urszula Kukliniska, Krzysztof Brzozka. Inhibition of CDK8 kinase with SEL120-34A allows for a personalized approach in AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2174. doi:10.1158/1538-7445.AM2017-2174