The main purpose of this study is to learn more about the safety and tolerability of abemaciclib when given in combination with hormone therapy in Indian women with advanced breast cancer. Participants must have hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) breast cancer and must live in India. For each participant, the study could last up to eight months and may include up to eight visits to the study center.

Inclusion Criteria:

• Have a diagnosis of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer
• Have locoregionally recurrent disease not amenable to resection or radiation therapy with curative intent or metastatic disease
• Have postmenopausal status
• Have a performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) scale
• Have adequate organ function
• Have discontinued previous cytotoxic therapies, biological agents, investigational agents, and radiotherapy
• Are able to swallow oral formulation

Exclusion Criteria:

• Have visceral crisis, lymphangitic spread, or leptomeningeal carcinomatosis.
• Have clinical evidence or history of central nervous system metastasis.
• Have received prior treatment with chemotherapy (except for neoadjuvant/adjuvant chemotherapy), fulvestrant, everolimus, or any cyclin-dependent kinase (CDK) 4 & 6 inhibitor.
• Have received recent (within 28 days prior to study intervention) live vaccination (for example, yellow fever). Seasonal flu vaccinations that do not contain a live virus are permitted.
• Have a personal history of presyncope or syncope of either unexplained or cardiovascular etiology, ventricular tachycardia, ventricular fibrillation, or sudden cardiac arrest.
• Have inflammatory breast cancer or a history of any other cancer (except nonmelanoma skin cancer or carcinoma in-situ of the cervix), unless in complete remission with no therapy for a minimum of 3 years.
• Have received an autologous or allogeneic stem-cell transplant
• Have clinically relevant active bacterial or fungal infection, or detectable viral infection (for example, human immunodeficiency virus or viral hepatitis). Screening is not required for enrolment.
• Are pregnant or breastfeeding.

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 European union (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.

All enrolled participants.

Baseline until end of follow-up (Up To 7 Months)

All participants who received at least one dose of study drug.