Identification of potent 5-pyrimidinyl-2-aminothiazole CDK4, 6 inhibitors with significant selectivity over CDK1, 2, 5, 7, and 9

5-Pyrimidinyl-2-aminothiazole 1 was identified as an inhibitor of cyclin-dependent kinases (CDKs) by a screening of the Merck sample repository. The introduction of a methyl group at the C-5 or C-6 position on the pyrimidine ring, directed toward the gate keeper residue of CDK4 (Phe93), led to significant enhancement of selectivity for CDK4 over other CDKs. Compound 3 exhibited more than 300-fold selectivity for CDK4 over CDK1, 2, 5, 7, and 9. Subsequent improvements in aqueous solubility afforded compound 4, which is available for further in vivo studies and this compound inhibited pRb phosphorylation and BrdU incorporation in tumor models.

Graphical abstractA novel series of CDK4, 6 selective inhibitors with a 5-pyrimidinyl-2-aminothiazole scaffold was identified. Especially, compound 4 exhibited significant selectivity for CDK4, 6 over CDK1, 2, 5, 7, and 9. Compound 4 also inhibited pRb phosphorylation and BrdU incorporation in tumor models.Figure optionsDownload full-size imageDownload as PowerPoint slide