A novel series of N-(pyridin-2-yl)-4-(thiazol-5-yl)pyrimidin-2-amines as highly potent CDK4/6 inhibitors

Aim: Inhibitors of CDK4/6 have emerged as a powerful class of therapeutics for treatment of several malignancies. We herein describe the identification of a new series of molecules that demonstrated excellent selectivity for CDK4/6 over CDKs1, 7 and 9. Results: Medicinal chemistry optimization led to the discovery of 58 and 69 that inhibited CDK4 and CDK4/6, respectively, with high potency and selectivity, and 58 and 69 exhibited potent antiproliferative activities in a panel of human cancer cell lines including leukemia, and cancers of the breast, colon, ovary, pancreas and prostate. Conclusion: Compounds 58 and 69 caused remarkable growth inhibition of melanoma cells, particularly the cells harboring multiple BRAF and NRAS mutations, via a CDK4/6-targeted mechanism of action. [GRAPHICS] .