CDKI-73: an orally bioavailable and highly efficacious CDK9 inhibitor against acute myeloid leukemia.

Acute myeloid leukemia (AML) is the most common form of acute leukemia with dismal long-term prognosis with age. The most aggressive subtype of AML is MLL-AML that is characterized by translocations of the mixed-lineage leukemia gene (MLL) and resistance to conventional chemotherapy. Cyclin dependent kinase 9 (CDK9) plays a crucial role in the MLL-driven oncogenic transcription, and hence, inhibiting activity of CDK9 has been proposed as a promising strategy for treatment of AML. We investigated the therapeutic potential of CDKI-73, one of the most potent CDK9 inhibitors, against a panel of AML cell lines and samples derived from 97 patients. CDKI-73 induced cancer cells undergoing apoptosis through transcriptional downregulation of anti-apoptotic proteins Bcl-2, Mcl-1 and XIAP by majorly targeting CDK9. Contrastively, it was relatively low toxic to the bone marrow cells of healthy donors. In MV4-11 xenograft mouse models, oral administration of CDKI-73 resulted in a marked inhibition of tumor growth (p < 0.0001) and prolongation of animal life span (P < 0.001) without causing body weight loss and other overt toxicities. The study suggests that CDKI-73 can be developed as a highly efficacious and orally deliverable therapeutic agent for treatment of AML.