Phase 3 Randomized, Placebo-Controlled Study to Assess Safety, Tolerability and Efficacy of Garetosmab in Patients with Fibrodysplasia Ossificans Progressiva
Fibrodysplasia ossificans progressiva (FOP) is an extremely rare condition where muscle, tendons, and other soft tissues gradually turn into bone. This trial is investigating whether an experimental medicine called garetosmab can prevent new bone from forming and reduce painful flare-ups. In this Phase 3 study, adult participants will be randomly chosen to receive either garetosmab or a dummy treatment (placebo). Because it is a double-blind trial, neither you nor your study doctor will know which treatment you are receiving during this phase. Doctors will track how many new areas of bone appear using scans, check your joint movement, and test your breathing over time. They will also keep a close eye on any side effects. Taking part in this research helps doctors understand whether garetosmab could be an effective, safe treatment for people living with FOP in the future.
At a glance
What is this study about?
Fibrodysplasia ossificans progressiva (FOP) is a very rare genetic condition that causes bone to form in places it should not, such as inside muscles, tendons, and ligaments. Over time, these extra bridges of bone can lock joints in place, making it difficult to move, walk, or breathe easily. FOP often causes painful swelling episodes called 'flare-ups' that lead to new bone formation.
In people with FOP, a faulty cell signal tells soft tissues to turn into bone. Garetosmab is an experimental medicine designed to attach to and block a specific protein involved in this signalling process, known as activin A. By turning down this faulty signal, scientists hope garetosmab can prevent new abnormal bone from forming and reduce the frequency and severity of flare-ups.
Phase 3 is usually the final major testing stage before a new medicine can be approved for general use. In this trial, researchers are comparing garetosmab directly against a placebo (an inactive dummy treatment) to prove whether the medicine truly makes a difference. They want to confirm that it is safe, well-tolerated, and effective at preserving movement and daily quality of life.
Key takeaways
- This Phase 3 trial tests whether garetosmab can prevent new bone formation in adults with FOP.
- Participants will be randomly assigned to receive either garetosmab or a dummy treatment (placebo).
- Doctors will closely monitor joint movement, lung function, flare-ups, and side effects.
- The treatment cannot remove old bone, but aims to stop new bone from forming.
- Joining is completely voluntary, and you can leave the study at any time.
Who may be eligible?
This study is open to adults aged 18 and older who have a confirmed clinical diagnosis of fibrodysplasia ossificans progressiva (FOP). Both men and women are eligible to take part.
Because FOP is a delicate condition, the study team will carry out thorough health checks before you can join. They will review your medical history, current mobility, and general well-being to make sure taking part is as safe as possible for you.
People who are pregnant, planning a pregnancy, breastfeeding, or who have certain other serious medical conditions may not be able to take part. The trial team will discuss the detailed medical checklist with you to see if the study is a good match.
Could this study suit you?
Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.
- I am aged 18 or older.
- I have a confirmed diagnosis of fibrodysplasia ossificans progressiva (FOP).
- I am willing to attend regular hospital visits for scans, blood tests, and breathing checks.
- I understand that I might receive a placebo (dummy treatment) instead of the active medicine.
- I am not currently pregnant or breastfeeding.
What does participation involve?
Taking part involves receiving regular doses of either garetosmab or a dummy treatment (placebo), usually given by injection. A computer chooses your treatment by chance, and neither you nor your doctor will know which one you receive. You will need to attend regular hospital appointments so the study doctors can check your health. These visits will include imaging scans to look for any new bone growth, joint movement assessments, simple breathing tests, and routine blood tests. You will also be asked to report any flare-ups or changes in your daily symptoms. The study team will explain the exact schedule of visits and total duration before you agree to take part.
Potential risks and benefits
Locations (6)
- —UnverifiedFinland
- —UnverifiedItaly
- —UnverifiedSpain
- —UnverifiedNetherlands
- —UnverifiedPoland
- —UnverifiedFrance
Common questions
What is a placebo and why is it used?
A placebo looks identical to the real medicine but contains no active ingredients. Comparing garetosmab to a placebo allows researchers to prove that any improvements or side effects are truly caused by the study drug.
Will I definitely receive garetosmab?
Not right away. You will be randomly assigned to receive either garetosmab or a placebo. In some trials, participants on placebo are offered the active medicine later in the study.
Can garetosmab remove bone that has already formed?
No, garetosmab is not designed to dissolve or remove existing bone. The goal of the treatment is to prevent new abnormal bone from developing.
Do I have to pay to take part in this study?
No. All study-related medicines, scans, and tests are provided free of charge, and trials often help cover reasonable travel expenses to and from the hospital.
What happens if I decide to leave the trial early?
You can leave the trial at any point. Your decision will not affect the ongoing quality of your usual NHS care or your relationship with your medical team.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
Interested in taking part?
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