208 (PB-032) Poster - Intrinsic tumor subtype in hormone receptor (HR) positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer (ABC) treated with cyclin-dependent kinase 4/6 inhibitors (CDK 4/6i) and endocrine therapy (ET) – a retrospective analysis of real world data

Abstract

Background: CDK 4/6 inhibitors significantly improve outcomes for patients (pts) with HR positive, HER2-negative ABC. In this group of patients, the HER2-Low (HER2-L) subtype represents 50–60% and is characterized by poor prognosis. In this retrospective analysis we explore the role of intrinsic tumor subtype (luminal A, luminal B and HER2-L) as a predictor of clinical outcomes in patients treated with ET plus CDK 4/6 inhibitors.