A Study to Learn About the Investigational Medicine Called PF-06821497 (Mevrometostat) in Men With mCRPC Who Were Previously Treated With Abiraterone Acetate for Prostate Cancer (MEVPRO-1).

To join this study, you would need to be a man with prostate cancer that has spread and is no longer responding to hormone treatment, and you must have previously received abiraterone acetate. Your cancer must have been confirmed by a doctor, and there should be clear signs that it has spread, either in your bones (seen on a bone scan) or in other parts of your body (seen on a CT or MRI scan). You also need to be generally well enough to take part, with doctors expecting you to live for at least another six months. Your ability to carry out daily activities will be assessed.

However, there are some reasons why you might not be able to join. For example, if you have other serious medical conditions like certain heart problems, active inflammatory stomach/gut issues, or if scans show that your cancer has spread to your brain. You also can't have received certain prostate cancer treatments recently, such as most forms of chemotherapy, specific hormone therapies (like enzalutamide, apalutamide, darolutamide), or other experimental treatments, within a certain period before the study starts. There are a few exceptions, like certain older hormone blockers or specific use of docetaxel long ago.

Your study doctor will carefully review your full medical history and all your current health details to determine if this study is suitable for you. They will explain all the criteria in detail.

If you decide to join this study, you will be randomly assigned to one of three treatment groups. This means neither you nor your doctor can choose which treatment you receive; it's decided by chance, like flipping a coin. You will receive either the new study medicine (PF-06821497) combined with enzalutamide, enzalutamide on its own, or docetaxel (chemotherapy).

Taking part will involve regular visits to the hospital or clinic for medical check-ups. During these visits, doctors will monitor your health, give you the study medication, perform blood tests, and conduct imaging scans (like CT scans or bone scans) to see how your cancer is responding. These follow-up visits will be important to track your progress and check for any side effects.

The total duration of your participation in the study will depend on how your cancer responds to the treatment and for how long you can safely receive the medication. Even after you stop the study treatment, there will likely be follow-up visits or phone calls to monitor your long-term health and any ongoing effects.