Management of Adverse Events Due to Cyclin-Dependent Kinase 4/6 Inhibitors.

Cyclin-dependent kinase (CDK) 4/6 inhibitors have become standard of care in the treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer. They have been shown to double the efficacy of endocrine-based treatment. Three oral agents are available to date: palbociclib, ribociclib, and abemaciclib. The aim of this article is to give a short overview of the existing efficacy data, to summarize the recommended clinical monitoring procedures for patients under CDK4/6 inhibitors, and to shed light on the clinical management of the most common treatment-emergent adverse events. The hematological class side effect neutropenia as well as non-hematological toxicities (e.g., impaired liver function, prolonged QTc interval, and diarrhea) are discussed. In addition, the current knowledge about relevant drug interactions is reviewed.