A Study to Learn About Vepdegestrant When Given With PF-07220060 to People With Advanced or Metastatic Breast Cancer.

To be considered for this study, you would need to have breast cancer that has been diagnosed by medical tests. Your cancer must have spread to other parts of the body and cannot be completely removed by surgery. It also needs to be sensitive to hormone therapy, meaning it's 'estrogen receptor positive', and should no longer be responding to your previous treatments.

You would also need to be at least 18 years old. Importantly, if you've had previous treatments, there are specific rules about how many types of treatment you've received before. Your general health and how well you can carry out daily activities will also be checked by the study doctors.

There are also reasons why you might not be able to join. For example, if your cancer is causing a life-threatening emergency, or if you have certain heart problems. If you have active brain tumours or other types of cancer diagnosed recently, you might not be able to participate. Also, if you can't properly absorb medicines, or are taking certain other medications or herbal supplements, it might affect your ability to join.

If you decide to take part in this study, you would take both study medicines, vepdegestrant and PF-07220060, by mouth at home. You would continue taking them until your cancer starts to grow again, or if you experience side effects that are too uncomfortable or serious.

You will have regular check-ups at the study clinic, typically about once every four weeks. During these visits, the medical team will monitor your health, check for any side effects, and see how the treatment is affecting your cancer. They will also carry out various tests, which might include blood tests, scans, and physical examinations. The total duration of your participation will depend on how you respond to the treatment and your tolerance to any side effects.