Abemaciclib has not been studied in head-to-head clinical trials with other cyclin D-dependent kinases (CDK) 4 and 6 inhibitors.

The mechanism of action of abemaciclib is provided below.

Abemaciclib is an inhibitor of CDK4 and CDK6 and was most active against cyclin D1/CDK4 in enzymatic assays. In breast cancer, cyclin D1/CDK4 has been shown to promote phosphorylation of the retinoblastoma protein (Rb), cell proliferation, and tumor growth. Abemaciclib prevents Rb phosphorylation, blocking progression from G1 into S phase of the cell cycle, leading to suppression of tumor growth in preclinical models following short duration target inhibition. In estrogen receptor–positive breast cancer cell lines, sustained target inhibition by abemaciclib prevents rebound of Rb phosphorylation and cell cycle reentry, resulting in senescence and apoptosis. In breast cancer xenograft models, abemaciclib dosed daily without interruption at clinically relevant concentrations—as a single agent or in combination with antiestrogens—resulted in reduction of tumor size.1

For information on other CDK 4 and 6 inhibitors in this class, please contact the individual manufacturers of these drugs.

VERZENIO® (abemaciclib) tablets, for oral use, Lilly