A Randomized, Open-Label, Phase 3 Study of Abemaciclib Combined With Standard Adjuvant Endocrine Therapy Versus Standard Adjuvant Endocrine Therapy Alone in Patients With High Risk, Node Positive, Early Stage, Hormone Receptor Positive, Human Epidermal Receptor 2 Negative, Breast Cancer


The purpose of this study is to evaluate the safety and efficacy of the study drug abemaciclib in participants with high-risk, node-positive, early-stage, hormone receptor positive (HR+), human epidermal receptor 2 negative (HER2-) breast cancer.

Study Arms

  • Experimental: Abemaciclib + Standard Adjuvant Endocrine Therapy
  • Standard Adjuvant Endocrine Therapy


  • The participant has confirmed HR+, HER2-, early-stage resected invasive breast cancer without evidence of distant metastases
  • The participant must have undergone definitive surgery of the primary breast tumor
  • The participant must have tumor tissue from breast (preferred) or lymph node for exploratory biomarker analysis available prior to randomization
  • Pathologic lymph node involvement
  • The participant must be randomized within 16 months from the time of definitive breast cancer surgery
  • The participant may receive up to 12 weeks of endocrine therapy until randomization following the last non-endocrine therapy (surgery, chemotherapy, or radiation) whichever is last