Predicting drug–drug interactions in breast cancer patients treated with CDK4/6 inhibitors and forward planning

Introduction Cyclin-dependent kinase (CDK) 4/6 inhibitors are cornerstones in the treatment of Hormone Receptor (HR) positive and Human Epidermal Growth factor (HER2) negative metastatic breast cancer. Given their widespread use in the metastatic setting and emerging use in the adjuvant setting, studying the drug-drug interactions (DDI) of these medications is of utmost importance.