Abemaciclib for the Treatment of Luminal Metastatic breAst caNcer in the Real-life Clinical pracTice in Russia.

Inclusion Criteria: 1. Age ≥18 years 2. Patients must have a diagnosis of HR+ breast cancer. To fulfill the requirement of HR+ disease, a breast cancer must express, by immunohistochemistry (IHC), at least one of the hormone receptors (ER, progesterone receptor \[PgR\]) as defined in the relevant American Society of Clinical Oncology/College of American Pathologists Guidelines: For ER and PgR assays to be considered positive, ≥1% of tumor cell nuclei must be immunoreactive by immunohistochemistry (IHC) 3. Patient has HER2-negative breast cancer defined as a negative in situ hybridization test or an IHC status of 0, 1+ or 2+. If IHC is 2+, a negative in situ hybridization (FISH, CISH, or SISH) test is required by local laboratory testing. 4. Patients with advanced (loco-regionally recurrent, or metastatic) breast cancer not amenable to curative therapy. 5. WHO performance status of 0-2 6. The patient has adequate organ function 7. Any number of prior therapies (including none) is permitted 8. Рatients who will start Abemaciclib as a Single Agent or in combination with endocrine therapy Exclusion Criteria: 1. Uncontrolled intercurrent illness including, but not limited to, known ongoing or active infection, including HIV, active hepatitis B or C, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia (specifically, atrial fibrillation or ventricular dysrhythmias except ventricular premature contractions), or psychiatric illness/social situations that would limit compliance with study requirements. 2. Participants must not be pregnant or breastfeeding