Clinical Research Trials

Key Trial Criteria

• Key Inclusion Criteria

  For a patient to be eligible for participation in this study, all of the following criteria must apply.

  • Women (regardless of menopausal status) or men ≥18 years of age (or per local regulations).
  • The participant has confirmed HR+, HER2-, early-stage resected invasive breast cancer without evidence of distant metastases.
  • The participant must have undergone definitive surgical treatment for the current malignancy.
  • The participant must have tumor tissue from the breast (preferred) or lymph node for exploratory biomarker analysis available prior to randomization.
  • The participant must have axillary lymph node involvement by tumor and have one of the following indicating a higher risk of relapse:
    • Four or more axillary lymph nodes involved with cancer
    • Tumor size of at least 5 centimeters
    • Grade 3 histology
    • Ki67 index by central analysis of ≥20% on untreated breast tissue
  • The participant must be randomized within 16 months from the time of surgery.
  • If the participant is currently receiving or initiating standard adjuvant endocrine therapy at the time of study entry, she/he must not have received more than 12 weeks of adjuvant endocrine therapy following his/her last non-endocrine therapy (surgery, chemotherapy, or radiation).
  • Participants must have recovered from the acute effects of chemotherapy and radiotherapy and from surgical side effects following definitive breast surgery.
  • Women of reproductive potential must have a negative blood pregnancy test and agree to use highly effective contraceptive methods.
  • The participant has an Eastern Cooperative Oncology Group (ECOG) performance status ≤1.
  • The participant has adequate organ function.
  • The participant is able to swallow oral medications.

• Key Exclusion Criteria

  A patient will not be eligible for participation in this study if any of the following criteria apply.

  • Stage IV (M1), Stage IA, and lymph node-negative breast cancer.
  • Participants with a history of previous breast cancer are excluded, with the exception of lobular carcinoma in situ (LCIS) or ductal carcinoma in situ (DCIS) treated by locoregional therapy alone ≥5 years ago. Participants with a history of any other cancer (except non-melanoma skin cancer or carcinoma in situ of the cervix), unless in complete remission with no therapy for a minimum of 5 years are excluded.
  • Females who are pregnant or lactating.
  • The participant has previously received treatment with any CDK4 and CDK6 inhibitor.
  • The participant is receiving concurrent exogenous reproductive hormone therapy (for example, birth control pills, hormone replacement therapy, or megestrol acetate).
  • The participant has previously received endocrine therapy for breast cancer prevention (tamoxifen or raloxifene or aromatase inhibitors).
  • The participant has a serious pre-existing medical condition(s) that, in the judgment of the investigator, would preclude participation in this study.
  • The participant has a personal history of any of the following conditions: syncope of cardiovascular etiology, ventricular arrhythmia of pathological origin or sudden cardiac arrest. Any participant with a history of venous thromboembolism (VTE) (for example, deep vein thrombosis [DVT] of the leg or arm and/or pulmonary embolism) will be excluded.
  • The participant has an active bacterial infection, fungal infection, or detectable viral infection or viral load.
  • The participant has received an experimental treatment in a clinical trial within the last 30 days or 5 half-lives, whichever is longer.