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Study on the Safety and Effectiveness of Garetosmab for Adults with Fibrodysplasia Ossificans Progressiva

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying a rare disease called Fibrodysplasia Ossificans Progressiva (FOP). FOP is a condition where soft tissues in the body, like muscles and tendons, gradually turn into bone, leading to stiffness and movement difficulties. The study is testing a treatment called Garetosmab, which is a type of medication known as a monoclonal antibody. Monoclonal antibodies are proteins designed to target specific substances in the body. In this case, Garetosmab is aimed at reducing the formation of new bone in soft tissues.

The purpose of the study is to evaluate the safety and effectiveness of Garetosmab compared to a placebo. Participants will receive the treatment through an intravenous (IV) infusion, which means the medication is given directly into a vein. The study will last for about 56 weeks, during which participants will be monitored for any new bone growth and any side effects they might experience. The study will use low-dose computed tomography (CT) scans to check for new bone formation.

Throughout the study, participants will have regular check-ups to assess their health and any changes in their condition. The study aims to provide valuable information on whether Garetosmab can help manage FOP by preventing new bone growth in soft tissues, ultimately improving the quality of life for those affected by this challenging condition.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon joining the study, an initial assessment is conducted to confirm the diagnosis of fibrodysplasia ossificans progressiva (FOP). This includes reviewing medical history and conducting necessary tests to ensure eligibility.

    Eligibility criteria include a clinical diagnosis of FOP, confirmation of a specific genetic mutation, and recent disease activity.

  2. Step 2

    Baseline evaluation

    A baseline evaluation is performed, which involves CT imaging to assess the current state of the condition. This serves as a reference point for future assessments.

  3. Step 3

    Treatment administration

    Participants are randomly assigned to receive either garetosmab or a placebo. Garetosmab is administered as an intravenous (IV) infusion.

    The treatment is given according to a schedule outlined in the study protocol, continuing up to week 56.

  4. Step 4

    Ongoing monitoring

    Throughout the study, regular monitoring is conducted to assess the safety and tolerability of the treatment. This includes tracking any adverse events and conducting routine health checks.

    Participants are required to undergo periodic CT scans to monitor the formation of new bone lesions.

  5. Step 5

    Interim evaluations

    Interim evaluations occur at weeks 28, 56, and 84. These evaluations include assessments of joint function, disease severity, and the occurrence of flare-ups.

    Both clinician and patient-reported outcomes are collected to provide a comprehensive view of the treatment's impact.

  6. Step 6

    Final assessment

    At the end of the study period, a final assessment is conducted to evaluate the overall efficacy and safety of the treatment.

    The primary focus is on the number of new bone lesions and any changes in disease symptoms or severity.

Who can join the trial?

7 criteria

  • The patient must have a clinical diagnosis of Fibrodysplasia Ossificans Progressiva (FOP). This means the patient has certain signs like unusual toe shape from birth, swelling of soft tissues, or extra bone growth in places it shouldn't be.
  • The patient must have confirmation of the FOP diagnosis with a specific genetic mutation called Type I activin A receptor (ACVR1) mutation.
  • The patient must have had FOP activity within the last year. This means experiencing pain, swelling, stiffness, or other symptoms related to FOP flare-ups, worsening joint function, or seeing more or bigger extra bone growths.
  • The patient must be willing and able to have CT imaging done. CT imaging is a special type of X-ray that helps doctors see inside the body.
  • Other specific criteria defined in the study protocol may also apply.
  • The study is open to both male and female patients.
  • The study includes patients from certain age groups, specifically children and adults.

Who cannot join the trial?

8 criteria

  • Patients who are pregnant or breastfeeding cannot participate.
  • Individuals with a history of severe allergic reactions to similar medications are excluded.
  • Patients with other serious health conditions that could interfere with the study are not eligible.
  • Participants who have taken part in another clinical trial within the last 30 days are not allowed.
  • Individuals who are unable to comply with the study procedures or follow-up visits are excluded.
  • Patients with a history of drug or alcohol abuse within the past year cannot participate.
  • Individuals who have received certain medications that might affect the study results are not eligible.
  • Patients with unstable mental health conditions that could affect their ability to participate are excluded.
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Investigated drugs

Garetosmab is a medication being studied for its potential to help patients with Fibrodysplasia Ossificans Progressiva, a rare condition where soft tissues gradually turn into bone. The trial aims to see if garetosmab can reduce the formation of new bone lesions over a period of 56 weeks. The study also focuses on understanding how safe and tolerable garetosmab is for patients during this time.

What is already known about the treatment

Garetosmab – Garetosmab is administered via injection and is currently being studied in clinical trials for its safety and effectiveness. It is primarily being investigated for the treatment of Fibrodysplasia Ossificans Progressiva, a rare condition where soft tissues progressively turn into bone. The medication works by targeting and inhibiting specific proteins involved in abnormal bone formation, aiming to prevent new bone growth in unwanted areas. Garetosmab is classified as a monoclonal antibody, which is a type of biological therapy designed to interfere with specific molecular pathways.

Investigated diseases

Fibrodysplasia Ossificans Progressiva – This is a rare genetic disorder where soft tissues, such as muscles and tendons, gradually turn into bone. This abnormal bone formation can lead to joint stiffness and restricted movement as the condition progresses. The disease often begins in childhood, with episodes of painful swelling and inflammation, known as flare-ups, which precede the ossification process. Over time, these flare-ups can result in the formation of new bone outside the normal skeleton, leading to significant physical limitations. The progression of the disease is unpredictable, with varying severity and frequency of flare-ups among individuals.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-508350-26-00Protocol codeR2477-FOP-2175Estimated enrolment66 patientsSponsorRegeneron Pharmaceuticals Inc.

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