The goal of this clinical trial is to evaluate the effect of patient education and patient typology-based coaching on therapy persistence in breast cancer patients taking ribociclib. Researchers will compare the time to permanent treatment discontinuation of patients receiving personalized coaching to the time to permanent treatment discontinuation of patients who only receive standard of care education and counselling, to see if adherence to treatment can be improved by personalized patient coaching.

Inclusion Criteria:

• Participant provides written informed consent prior to the beginning of trial-specific procedures.
• Patients must be aged ≥18 years on the day of signing informed consent.
• Participant has histologically confirmed primary invasive adenocarcinoma of the breast.
• Participant has a histologically and/or cytologically confirmed diagnosis of ER-positive and/or progesterone receptor-positive breast cancer based on the most recently analyzed tissue sample tested by a local laboratory.
• Participant has HER2neg breast cancer defined as a negative ISH test or an IHC status of 0, 1+, or 2+. If the IHC is 2+, a negative ISH (e.g., FISH, CISH, SISH, or DISH) test is required by local laboratory testing and based on the most recently analyzed tissue sample.
• Indication for treatment with ribociclib in combination with an aromatase inhibitor for early breast cancer according to the valid SmPC.
• Participant has adequate organ function amenable for treatment with ribociclib as assessed by a local laboratory.
• Female participants of childbearing potential must have had a hysterectomy or be willing to use highly effective methods of contraception and have a confirmed negative pregnancy test as assessed by local in-house standard.
• Participant is willing and able to comply with scheduled visits, treatment plans, and other trial procedures.

Exclusion Criteria:

• Patients with distant metastases of breast cancer beyond regional lymph nodes (stage IV according to AJCC 8th edition) and/or evidence of recurrence after curative surgery.
• Patients with serious preexisting medical condition(s) that would preclude participation in this study.
• Women who are pregnant or lactating.
• Patients with active bacterial infections (requiring IV antibiotics at time of initiating study treatment), fungal infections, or detectable viral infections (e.g., known human immunodeficiency virus positivity or known active hepatitis B or C, such as hepatitis B surface antigen-positive]).
• Patients with a personal history in the past 5 years of any of the following conditions: syncope of cardiovascular etiology, ventricular arrhythmia of pathological origin (including, but not limited to, ventricular tachycardia and ventricular fibrillation), or sudden cardiac arrest.
• Patients with contraindications against ribociclib according to the current SmPC.
• Patients with hypersensitivity to active substance of ribociclib, peanuts, soya or one of the other ingredients
• Patients who are not eligible for the trial due to severe comorbidities other than those mentioned above or unavailability according to the treating physician.