ESMO20 YO for YO: highlights on adjuvant CDK4/6 inhibitors in early hormone receptor-positive/HER2-negative breast cancer

Abstract

ESMO20 virtual conference brought us the results of two major randomized trials on the adjuvant use of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) for early hormone receptor (HR) positive, human epidermal growth factor receptor 2 (HER2) negative breast cancer (BC). The two studies, PALLAS with palbociclib (ClinicalTrials.gov identifier NCT02513394) and monarchE with abemaciclib (NCT03155997), reported conflicting results. In the latter, adding abemaciclib for 2 years to standard endocrine therapy improved both the primary endpoint, invasive disease-free survival (DFS) with an absolute improvement of 3.5% at 2 years, as well as distant relapse-free survival (DRFS) with an absolute improvement of 3.3% at 2 years.