An Efficacy and Safety Study of Luspatercept (ACE-536) Versus Placebo in Subjects With Myeloproliferative Neoplasm-Associated Myelofibrosis on Concomitant JAK2 Inhibitor Therapy and Who Require Red Blood Cell Transfusions

To join this study, you need to be at least 18 years old and have a confirmed diagnosis of myelofibrosis. Critically, you must be experiencing anaemia that requires regular red blood cell transfusions. This means you’ve had between 4 and 12 red blood cell units over the last 12 weeks, and you haven’t gone longer than six weeks without a transfusion.

You must also already be taking a JAK2 inhibitor medication for your myelofibrosis. This medication needs to have been stable (same dose, no interruptions) for a certain period before the study starts. Your general health should also be reasonably good, as assessed by a doctor, meaning you're able to carry out most daily activities.

There are also some types of other medications or therapies that you cannot be taking while in this study, such as certain cancer drugs (other than your JAK2 inhibitor), specific blood cell growth factors, or certain older medications for blood conditions. Your study doctor will review all your current medications carefully to make sure you can safely participate.

If you decide to take part, the study will involve several stages. First, there's a 'screening period' where doctors will check if you meet all the requirements. If you do, you'll enter the 'treatment phase'. This phase starts with a period where you'll receive either Luspatercept or a placebo, and neither you nor your doctors will know which one. This part lasts for around six months. During this time, you will continue your usual JAK2 inhibitor treatment and other supportive care, like blood transfusions if needed.

Around day 169 (about 5.5 months), your response to the treatment will be checked. If you haven't shown improvement, you'll have the option to find out if you were on the active drug or placebo. If you were on the placebo, you might then be able to receive Luspatercept. The study involves regular clinic visits for assessments, blood tests, and to get your study medication. You'll then have a follow-up period after your treatment ends. The total duration of your involvement could be quite long, potentially over a year, depending on which treatment arm you are in and if you continue into the extension periods.