In the preplanned interim analysis of #monarchE trial, the addition of #abemaciclib to adjuvant endocrine therapy improved the invasive disease-free survival (IDFS) and distant relapse-free survival (DRFS) for patients with HR–positive, HER2-negative, node-positive, high-risk #breast_cancer regardless of KI67 index.

In this randomized, phase 3 trial, presented in SABCS-2022 and recently published in the Lancet, high risk patients were randomly assigned to receive 150 mg of abemaciclib BID for 2 years in addition to standard-of-care endocrine therapy or endocrine therapy alone.

At a median follow-up of 4 years, the absolute iDFS gain with addition of abemaciclib was 6·4% (48m iDFS rate of 85·8% in the abemaciclib plus endocrine therapy group vs 79·4% in the endocrine therapy alone group), HR= 0·664 , p<0·0001. The 4-year DRFS absolute difference was 5.9% (88.4% vs 82.5%) with the benefit for those who received abemaciclib compared to 4.1% difference at 3 years (HR = 0.659, P < 0.0001). Overall survival is still immature.

This updated analysis confirms the maintained benefit and the carryover effect of adjuvant abemaciclib in high risk HR+ patients.