Detection of Tumor DNA in the Blood of Patients Receiving Standard Therapy for Hormone Receptor-positive (HR+) Non-HER2 Expressing (HER2-) Metastatic Breast Cancer as a Tool to Select Those Who May Benefit From the Next Course of Fulvestrant in Combination With Alpelisib or Ribociclib

To be part of the initial screening phase of this study, you need to be at least 18 years old and have breast cancer that has spread, confirmed by tests. Your cancer must also be hormone receptor-positive and HER2-negative. You should not have received treatment yet for advanced cancer, but you should be eligible to start a standard treatment combining a drug called a CDK4/6 inhibitor with fulvestrant.

There are also some things that would mean you couldn't join. For example, if you've already had certain types of cancer drugs before, or if you have uncontrolled diabetes, or certain brain problems. You also need to be able to visit the clinic regularly and follow the study instructions carefully.

If you join the study, you'll first go through a screening phase where a blood test will check for cancer DNA. If certain cancer DNA is found, and you meet all the other criteria, you might be invited to the main treatment part of the study. In this phase, you would be randomly assigned to receive either alpelisib or ribociclib, both given alongside fulvestrant.

You would have regular doctor visits, blood tests, and scans to check how you're responding to the treatment. These visits will help the doctors monitor your health and the cancer. The total length of your involvement would depend on how your cancer responds to the treatment. You will continue with the study treatments and follow-up for as long as the treatment is helping and you are tolerating it well.