• Histopathologically or cytologically confirmed ER-positive (≥ 10% by immunohistochemistry \[IHC\]), HER2-negative \[IHC = 0 or 1, or (IHC = 2 and in situ hybridization \[ISH\]-negative)\] on tumor biopsy or final surgical pathology specimen early stage resected invasive breast cancer without evidence of recurrence or distant metastases, per local laboratory, according to the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines

• Participants considered at high risk of recurrence at initial staging

• Participants who have received at least 24 months but not more than 60 months of endocrine therapy (AIs or tamoxifen) with or without a CDK 4 and CKD 6 inhibitor (CDK4/6i)

• Participants who received prior CDK4/6i or a poly adenosine diphosphate-ribose polymerase (PARP) inhibitor must have already completed or discontinued these treatments.