How to Select a CDK4/6 Inhibitor in Early or Metastatic Breast Cancer
Key Points
- When choosing a CDK4/6 inhibitor for patients with breast cancer in the adjuvant or metastatic setting, clinicians should consider side effect profiles and patient characteristics.
- In adjuvant therapy, abemaciclib has slightly stronger efficacy signals, but has stricter eligibility criteria compared with ribociclib.
- In the metastatic setting, ribociclib has more robust survival data, although treatment selection should prioritize tolerability based on patients’ comorbidities.
At the Advancements in Oncology event from the Oncology Brothers podcast, Giuseppe Curigliano, MD, PhD, of European Society of Medical Oncology, and Arya Mariam Roy, MD, of The Ohio State University Comprehensive Cancer Center, discussed how to select CDK4/6 inhibitors in patients with hormone receptor (HR)–positive, HER2–negative breast cancer in the adjuvant or metastatic settings.
In HR–positive, HER2–negative early breast cancer, abemaciclib and ribociclib are approved CDK4/6 inhibitors in the adjuvant setting based on the monarchE and NATALEE trials, respectively. Between the two trials, monarchE had more narrow eligibility criteria that resulted in a slightly higher-risk population compared with NATALEE. Consequently, Dr. Curigliano prefers abemaciclib for higher-risk patients eligible for either agent. However, he would not hesitate to switch to ribociclib in high-risk patients that are not tolerating abemaciclib.
In the HR–positive, HER2–negative metastatic breast cancer setting, abemaciclib, ribociclib, and palbociclib are approved CDK4/6 inhibitors. Generally, treatment should be selected based on patient characteristics. Ribociclib may be less tolerable for patients with cardiac comorbidities, while abemaciclib may be less tolerable for patients with gastrointestinal comorbidities. Palbociclib is still an appropriate choice for elderly or frail patients that may not tolerate other agents. If a patient has no contraindications, Dr. Curigliano’s first preference is for ribociclib based on slightly more robust efficacy data in metastatic clinical trials.