Definition

An inhibitor of cyclin-dependent kinase (CDK) types 4 (CDK4) and 6 (CDK6), with potential antineoplastic activity. Upon administration, CDK4/6 inhibitor QLS12004 selectively targets and inhibits CDK4 and CDK6, which inhibits the phosphorylation of retinoblastoma protein (Rb) early in the G1 phase and prevents CDK-mediated G1-S-phase transition. This leads to cell cycle arrest, the induction of apoptosis, and the inhibition of tumor cell proliferation. CDKs are serine/threonine kinases that are important regulators of cell cycle progression and cellular proliferation and are upregulated in many tumor cell types.