A pyrazolo[1,5-a]pyrimidine with potential antineoplastic activity. Dinaciclib selectively inhibits cyclin dependent kinases CDK1, CDK2, CDK5, and CDK9; inhibition of CDK1 and CDK2 may result in cell cycle repression and tumor cell apoptosis. OR A substance being studied in the treatment of advanced melanoma (a type of skin cancer) and other types of cancer. It blocks cell division and may cause cancer cells to die. It is a type of cyclin-dependent kinase inhibitor. Also called CDK inhibitor SCH 727965.