TRADE: Dose Escalation Tolerability of Abemaciclib in HR+ HER2- Early Stage Breast Cancer

This research study is a prospective, single-arm, open label, phase 2 study designed to evaluate if a dose-increasing strategy for abemaciclib will have less side effects and be better tolerated than the standard dosage of abemaciclib for participants with early-stage high-risk hormone receptor positive breast cancer. This research study involves adjuvant abemaciclib plus endocrine (anti-hormone) therapy that works to target breast cancer. Adjuvant therapy is treatment given after surgery, chemotherapy, and/or radiation therapy. The U.S. Food and Drug Administration (FDA) has approved abemaciclib as a treatment option for early-stage high-risk hormone receptor breast cancer. The FDA has also approved hormonal therapies as treatment for hormone receptor positive breast cancer. The research study procedures include screening for eligibility, study treatment including laboratory evaluations and questionnaires, blood tests, tumor biopsies, and stool collections. Participation in this research study is expected to last for at least 2 years and up to 5 years. It is expected that about 90 people will take part in this research study. Eli Lilly and Company is supporting this study by providing funding for the study and supplying the study drug, abemaciclib.