Overview CDK 4/6 Inhibitor, Ribociclib, With Adjuvant Endocrine Therapy for ER-positive Breast Cancer Status: Recruiting Trial end date: 2026-10-01 Target enrollment: Participant gender: Summary This research study is studying a drug as a possible treatment for ER-positive Breast Cancer The drug involved in this study is: -Ribociclib Phase: Phase 2 Details Lead Sponsor: Massachusetts General HospitalCollaborator: Novartis