Phase III Study to Evaluate the Safety, Efficacy, and Impact on Quality of Life of Capivasertib Alongside Standard-of-care Endocrine Treatment in Patients With HR+/HER2- Advanced Breast Cancer and Progression on Prior Endocrine-based Treatment

This is a multicentre phase-III-trial to evaluate the use of capivasertib in patients with HR+/HER2- advanced breast cancer and progression on prior endocrine-based treatment. The goal of this study is 1. To evaluate benefit of capivasertib regarding time to next treatment (TTNT1) - i.e., time "on treatment" with capivasertib. 2. To evaluate the benefits of patient reported outcome(PRO)-adherence regarding the deterioration of quality of life (DQoL)-free interval. There is no active comparison group but a historical control group consisting of data of patients treated within the CAPItello-291-study.. Participants will take capivasertib accompanied by standard of care endocrine treatment and are asked to document ther quality of life on standardised questionnaires. Optionally, patients can use eHealth support via their own smart phones.