NCIt definition : The isethionate salt form of dalpiciclib, an orally bioavailable cyclin-dependent
kinase (CDK) inhibitor, with potential antineoplastic activity. Upon oral administration,
dalpiciclib selectively inhibits cyclin-dependent kinase 4 (CDK4) and 6 (CDK6). This
inhibits retinoblastoma (Rb) protein phosphorylation early in the G1 phase, which
prevents CDK-mediated G1-S phase transition and leads to cell cycle arrest. This suppresses
DNA replication and decreases tumor cell proliferation. CDK4 and 6 are serine/threonine
kinases that are upregulated in many tumor cell types and play a key role in the regulation
of cell cycle progression.;