CDK4 and 6 are central regulators of cell cycle entry. The CDK4/6 pathway is frequently deregulated in breast cancer, and strategies to target this pathway have recently been proven to be effective in breast cancer patients. Preclinical and clinical data suggest that CDK4/6 inhibitors might be particularly useful in patients with hormone receptor-positive or HER2-positive tumors, while the role of such inhibitors in triple-negative breast cancer is still controversial.
