CDKinhibiittorit

CDKinhibiittorit, or cyclin-dependent kinase inhibitors, are a class of small-molecule drugs that block the activity of cyclin-dependent kinases (CDKs), enzymes essential for cell cycle progression and transcription. They include compounds that selectively target specific CDKs (such as CDK4/6) and broader agents that inhibit multiple CDKs. These drugs are primarily studied and used in oncology, often in combination with other anticancer therapies.

Mechanism of action

CDKinhibiittorit exert their antitumor effects by preventing phosphorylation of key cellular regulators. CDK4/6 inhibitors, for example, impair phosphorylation of the retinoblastoma (Rb) protein, halting cells in the G1 phase and limiting S phase entry. Some inhibitors also affect transcriptional regulation by targeting other CDKs (such as CDK7 and CDK9), which can influence RNA polymerase II activity and gene expression.

Clinical use and examples

The most successful and widely used CDKinhibiittorit are CDK4/6 inhibitors—palbociclib, ribociclib, and abemaciclib. They are approved for estrogen receptor–positive, HER2-negative advanced or metastatic breast cancer, typically in combination with hormonal therapies. Beyond breast cancer, CDKinhibiittorit are being investigated in a variety of malignancies and in different therapeutic combinations. Pan-CDK inhibitors, which target multiple CDKs, have shown activity in preclinical models but are generally limited by higher toxicity in clinical settings.

Adverse effects and considerations

Common adverse effects include neutropenia, leukopenia, fatigue, nausea, diarrhea, and liver enzyme elevations. Because of hematologic toxicity, regular blood count monitoring and dose adjustments are often required. Resistance can emerge through alterations in RB1 or other components of the cell cycle pathway, limiting long-term efficacy in some patients. In addition to antitumor activity, some CDK inhibitors (such as trilaciclib) are used to protect bone marrow during chemotherapy, a separate clinical application from direct tumor inhibition.

Overall, CDKinhibiittorit represent a targeted approach to disrupt cell cycle control in cancer, with approved indications focused on breast cancer and ongoing research across multiple tumor types.