194P Efficacy and safety of abemaciclib in younger patients with early breast cancer in the monarchE trial

Two years (y) of adjuvant abemaciclib + endocrine therapy (ET) resulted in sustained improvement in invasive disease-free survival (IDFS HR=0.68, 5 y rates: 84% abemaciclib + ET vs 76% ET, 8% absolute benefit) in patients (pts) with hormone receptor positive, human epidermal growth factor receptor 2 negative, node-positive, high-risk early breast cancer (EBC). Younger pts (≤40y) often have more aggressive disease. We assessed efficacy and safety data in pts ≤40 and >40y in monarchE.