CDK4/6 Inhibitors: Paving the Way for HR-Positive, HER2-Negative Early Breast Cancer

Cyclin-dependent kinase (CDK) 4/6 inhibitors are revolutionizing care for patients with advanced and metastatic hormone receptor–positive (HR+) and human epidermal growth factor receptor 2–negative (HER2–) breast cancer. These oral agents, often combined with other hormone-based therapy, have demonstrated considerable success in clinical trials and are used widely in oncology practices. CDK4/6 inhibitors are also being investigated for the treatment of early stage HR+, HER2– breast cancer. The addition of abemaciclib to adjuvant endocrine therapy improved invasive disease-free survival and distant relapse-free survival compared with endocrine therapy alone in patients with HR+, HER2–, node-positive, high-risk early breast cancer, and is now FDA-approved as adjuvant treatment in this setting. Here we review recent clinical data supporting the use of CDK4/6 inhibitors in both early and metastatic breast cancer. In addition, an expert faculty panel will discuss practical strategies to promote and improve adherence and side effect management in patients being treated with oral CDK4/6 inhibitors.