Inhibition of the Cyclin-Dependent Kinases (CDK) 4/6 as Therapy for Estrogen Receptor Positive Breast Cancer

Endocrine therapy (ET) is the usual first-line therapy for patients with hormone receptor-positive metastatic breast cancer (HR+MBC). However, resistance to ET frequently occurs during the course of treatment. Cellular pathways involved in cell proliferation are targets for new drugs that interfere with development of resistance to ET. Cyclin-dependent kinases (CDKs) are a subgroup of serine/ threonine kinases that play a key role in regulating cell cycle progression. In this review, we discuss the currently approved and under investigation CDK 4/6 inhibitors, in addition to their preclinical data and clinical trials that demonstrated their benefit in the treatment of HR+ breast cancer.