Adjuvant abemaciclib for high-risk breast cancer: the story continues

The development of selective inhibitors of cyclin dependent kinases 4 and 6 (CDK4/6i) has transformed the management of hormone receptor (HR) positive, human epidermal growth factor receptor 2 (HER2) negative metastatic breast cancer (BC).1 The addition of a CDK4/6i to endocrine therapy improves response rates, progression-free and overall survival with manageable toxicity.2,3 Consequently, three CDK4/6i, palbociclib, ribociclib, and abemaciclib, have gained regulatory approval for metastatic BC.