Strategic decision due to emerging new data for patients with HR+, HER2- metastatic breast cancer.

The reason for this study is to see if the drug abemaciclib in combination with nonsteroidal aromatase inhibitors (anastrozole or letrozole) is effective in participants with Hormone Receptor Positive (HR+), Human Epidermal Growth Factor Receptor 2 Negative (HER2-) advanced breast cancer that have certain disease characteristics.

Inclusion Criteria:

• Participants must have completed (neo) adjuvant endocrine therapy and have cancer return after at least 12 months or have de novo cancer that has spread to other organs at diagnosis

• Participants must have 1 or more of the following:

  • A high grade tumor in tissue
  • Negative progesterone receptor (PR) status
  • Have cancer that has spread to the liver
  • Have a treatment-free interval (TFI) <36 months

• Participants must have HR+, HER2- breast cancer

• Participants must have adequate organ function

Exclusion Criteria:

• Participants must not have cancer that has spread to other organs that has severely affected their function
• Participants must not have cancer that has spread to the brain that is unstable or untreated
• Participants must not have received endocrine therapy in the metastatic setting
• Participants must not have known active infection
• Participants must not have received prior endocrine therapy and had disease return within 12 months from completion of treatment
• Participants must not have received prior treatment with any cyclin-dependent kinase (CDK) 4 & 6 inhibitor or everolimus

Anonymized individual patient level data will be provided in a secure access environment upon approval of a research proposal and a signed data sharing agreement.

Data are available 6 months after the primary publication and approval of the indication studied in the US and EU, whichever is later. Data will be indefinitely available for requesting.

A research proposal must be approved by an independent review panel and researchers must sign a data sharing agreement.