Dinaciclib (SCH727965) is a novel and potent CDK inhibitor for CDK2, CDK5, CDK1 and CDK9 with IC50 of 1 nM, 1 nM, 3 nM and 4 nM, respectively. It also blocks thymidine (dThd) DNA incorporation. 

Cyclin-dependent kinases (CDKs) are critical positive regulators of cell cycle progression and cellular transcription whose dysregulation can lead to the development of cancer. Dinaciclib inhibits CDK1, CDK2, CDK5, and CDK9 activity in vitro with IC50 values of 3, 1, 1, and 4 nM, respectively.Compared to the pan-CDK inhibitor flavopiridol, dinaciclib is an equally potent inhibitor of CDK1 and CDK9 but a 12-14-fold more potent inhibitor of CDK2 and CDK5.It has been shown to inhibit DNA synthesis by blocking thymidine incorporation in A2780 ovarian cancer cells with an IC50 value of 4 nM.At 5 mg/kg it prevents tumor growth by 50% in an A2780 ovarian carcinoma mouse xenograft model and is active against a broad spectrum of human tumor cell lines in vitro (IC50s = 7-17 nM).