Overview Letrozole and CDK 4/6 Inhibitor for ER Positive, HER2 Negative Breast Cancer in Postmenopausal Women Status: Unknown status Trial end date: 1969-12-31 Target enrollment: Participant gender: Summary This is a phase II study evaluating the efficacy and safety of the pre-operative use of letrozole plus PD 0332991 (combination therapy) Phase: Phase 2 Details Lead Sponsor: Organisation for Oncology and Translational ResearchTreatments: LetrozolePalbociclib