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 study is looking for both women and men, aged 18 or older, who have been diagnosed with advanced breast cancer that is HR-positive and HER2-negative. This means your cancer responds to hormones and doesn't have too much of the HER2 protein.

For women, this includes those who are pre-menopausal, peri-menopausal, or post-menopausal. If you are pre- or peri-menopausal, you'll need to be receiving hormone-blocking treatment (called a GnRH agonist) at the start of and throughout the study. Post-menopausal women are defined by certain age or time since last period criteria, or if they've had their ovaries removed.

Your most recent tumour sample must show that your cancer is HR-positive (meaning it has estrogen receptors) and HER2-negative (meaning it does not have an excess of the HER2 protein). A medical expert will check these details from your biopsy results.

If you decide to take part, you will be taking the study drug, capivasertib, by mouth, four days a week with three days off. You will also continue with your regular hormone therapy, which might be an injection (fulvestrant) every 28 days or another type of hormone treatment. You will also be asked to regularly fill out questionnaires about your quality of life, which some patients may choose to do using their smartphone.

There will be regular follow-up appointments with your study team. The capivasertib treatment will continue as long as it is working for you, you are tolerating it well, or until the study officially ends. You will be monitored from the time you join until the end of the entire study, which could be several years, or until your death, whichever comes first. The total study is expected to run until early 2030, with individual participation in treatment varying based on your response.