Cyclin-Dependent Kinase 4 and 6 Inhibitors as Breast Cancer Therapy: Research Progress and Prospects

Cyclin-dependent kinases 4 and 6 (CDK4/6) are the core part of the cell cycle control machinery, which bind to cyclin D to regulate cell G1-S cycle conversion. CDK4/6 inhibitors are currently used to treat HR-positive and HER2-negative (HR+/HER2-) metastatic breast cancer (MBC), and the US FDA has approved three CDK4/6 inhibitors as palbociclib, ribociclib and abemaciclib. In order to provide better reference for the development of CDK4/6 inhibitors, this review summarized the research progress of CDK4/6 inhibitors. Potential drug resistance mechanism and combining medication strategies have been reviewed to reduce the occurrence of drug resistance. CDK4/6 inhibitors combined with fulvestrant or anastrozole showed positive efficacy in the treatment of breast cancer. Reducing the side effects is the crux of the development of CDK4/6 inhibitors in the future.