AuthorisedTherapeutic confirmatory (Phase III)Interventional

A Phase 3, Randomized, Double-Blind, Active-Control Study of Pelabresib (DAK539) and Ruxolitinib vs. Placebo and Ruxolitinib in Adult Patients with Myelofibrosis who are JAK inhibitor naive

This research is a 'Phase 3 trial' for adults with myelofibrosis, a condition affecting the bone marrow. The study aims to find out if combining a new medicine called pelabresib (DAK539) with an existing drug, ruxolitinib (Jakavi), is better than ruxolitinib alone. People joining will be randomly split into two groups: one receiving both pelabresib and ruxolitinib, and the other receiving ruxolitinib plus a placebo (a dummy pill). Researchers will compare how well each group's spleen shrinks and if their symptoms improve. This is an important step to see if this new combination treatment could become available for more people in the future.

At a glance

Status

Authorised

Phase

Therapeutic confirmatory (Phase III)

Sponsor

Novartis Pharma AG

Enrolment target

173

Start

29 May 2026

Myelofibrosis

What is this study about?

This clinical trial is designed for people living with myelofibrosis, a long-term condition where the bone marrow, which usually makes blood cells, becomes scarred. This scarring can lead to severe tiredness, a swollen spleen, and other challenging symptoms. The main goal of this study is to investigate a new treatment approach.

The trial is looking at a new medicine called pelabresib (also known as DAK539) when given alongside an approved treatment called ruxolitinib (Jakavi). Ruxolitinib is already used to help manage myelofibrosis symptoms and spleen size. The study wants to see if adding pelabresib to ruxolitinib works better than just taking ruxolitinib on its own. To do this fairly, some participants will receive the new combination, while others will receive ruxolitinib plus a placebo, which looks like pelabresib but contains no active medicine. This 'blinded' approach helps ensure the results are accurate and unbiased.

Throughout the study, doctors will closely monitor changes in spleen size, which is a common problem in myelofibrosis. They will also track how people's symptoms improve. These measurements will help determine if the new combination treatment is effective and could potentially offer a new way to manage myelofibrosis more successfully in the future. This is a Phase 3 study, which means it's one of the final steps before a new treatment might be considered for wider use.

Key takeaways

This study explores a new drug called pelabresib for myelofibrosis.
It combines pelabresib with an existing drug, ruxolitinib.
The goal is to see if the combination shrinks the spleen and improves symptoms.
Participants will be randomly assigned to receive either the new combination or ruxolitinib with a placebo.
This is a Phase 3 trial, a crucial step for potential new treatments.
Adults with myelofibrosis who haven't taken JAK inhibitors before may be eligible.

Who may be eligible?

This study is open to adult men and women, aged 18 or older, who have been diagnosed with myelofibrosis. It's specifically for people who haven't yet received treatment with a type of medicine called a JAK inhibitor – ruxolitinib is one example of a JAK inhibitor.

There are other specific medical requirements that would need to be checked by a doctor. These typically include things like your overall health, other medical conditions you might have, and certain blood test results. This helps ensure that the study is safe for you and that the results can be properly understood.

Quick self-check

Are you 18 years old or older?
Have you been diagnosed with myelofibrosis?
Have you NOT taken a medicine called a JAK inhibitor (like ruxolitinib) before?
Are you prepared for regular hospital visits and check-ups?
Are you able to provide your informed consent to participate?

This is a guide only — the research team will confirm whether you can take part.

What does participation involve?

If you decide to take part, you would be randomly assigned to one of two groups. One group would receive the new drug pelabresib along with ruxolitinib, and the other group would receive ruxolitinib with a placebo (a dummy pill). You will not know which group you are in, and neither will your doctor, which helps keep the study fair.

Your participation would involve regular visits to the clinic for check-ups. These visits will include various assessments, such as physical examinations, blood tests, and scans (like an MRI or CT scan) to measure your spleen size. You would receive the study medications as prescribed. The researchers will also ask you to complete questionnaires to track your symptoms. The exact number of visits, tests, and the total duration of your participation would be explained in detail by the study team, as it varies depending on your progress in the trial.

Potential risks and benefits

Taking part in a clinical trial offers potential benefits, such as access to a new treatment before it's widely available and closer monitoring of your health by medical professionals. However, there are also potential risks, including side effects from the medications, which can vary from mild to more serious. The new drug may not work for you, or it might not be better than existing treatments. The research team will discuss all known risks and benefits with you in detail, and you will receive a patient information sheet. Remember, you can choose to withdraw from the study at any time, for any reason, without affecting your usual medical care.

Locations (9)

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Belgium
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Germany
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Austria
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Poland
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Spain
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Italy
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Netherlands
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Czechia
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France

Common questions

What is myelofibrosis?

Myelofibrosis is a rare condition where the bone marrow, which should produce blood cells, becomes scarred. This can lead to tiredness, a swollen spleen, and other symptoms.

What is a 'Phase 3' trial?

A Phase 3 trial is a large study that compares a new treatment with an existing one or a placebo. It's usually one of the final steps before a new treatment can be considered for approval.

What does 'randomized and double-blind' mean?

Randomized means you're put into a treatment group by chance, like flipping a coin. Double-blind means neither you nor your doctors will know which treatment you are receiving, which keeps the study fair.

What are they trying to find out?

The main things they want to know are if the new combination treatment can shrink the spleen by at least 35% and if it can significantly improve your symptoms after 24 weeks.

Will I get a 'placebo'?

If you join, you will be randomly assigned to one of two groups. One group gets pelabresib with ruxolitinib, and the other gets ruxolitinib with a placebo (a dummy pill instead of pelabresib).