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Study on Efgartigimod IV for Adults with Seronegative Generalized Myasthenia Gravis

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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 condition known as Generalized Myasthenia Gravis, specifically in patients who do not have certain antibodies called acetylcholine receptor binding antibodies. This condition is a chronic autoimmune disorder that causes muscle weakness. The study will evaluate a treatment called Efgartigimod IV, which is a medication given through an intravenous infusion. This means the medicine is delivered directly into the bloodstream through a vein. The purpose of the study is to determine how effective and safe this treatment is compared to a placebo in managing the symptoms of this condition.

Participants in the study will receive either the Efgartigimod IV treatment or a placebo. The study is designed to be double-blinded, meaning neither the participants nor the researchers will know who is receiving the actual treatment or the placebo. This helps ensure that the results are unbiased. The study will follow a structured plan over a period of time, during which participants will be monitored for changes in their symptoms and any side effects they may experience.

The trial aims to provide valuable information about the potential benefits of Efgartigimod IV for people with Generalized Myasthenia Gravis who are seronegative for acetylcholine receptor binding antibodies. By comparing the effects of the treatment to those of a placebo, researchers hope to better understand how this medication can help manage the condition and improve the quality of life for those affected. Participants will be closely observed throughout the study to ensure their safety and to gather comprehensive data on the treatment's impact.

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

    Joining the study

    Upon joining the study, the participant will be informed about the trial's purpose and procedures. The participant must provide informed consent, confirming understanding and agreement to comply with the study requirements.

  2. Step 2

    Initial assessment

    An initial assessment will be conducted to confirm eligibility. This includes verifying age, medical history, and current treatment for generalized myasthenia gravis (gMG). Women of childbearing potential will undergo pregnancy testing.

  3. Step 3

    Randomization

    Participants will be randomly assigned to receive either the investigational drug efgartigimod IV or a placebo. This process is double-blinded, meaning neither the participant nor the study team will know which treatment is being administered.

  4. Step 4

    Treatment administration

    The treatment involves receiving efgartigimod IV or placebo through an intravenous infusion. The dosage is 20 mg/mL, and the frequency and duration will be specified by the study protocol.

  5. Step 5

    Monitoring and follow-up

    Participants will be monitored regularly to assess the treatment's effects and any side effects. This includes measuring changes in the MG-ADL and QMG scores from baseline to day 29.

  6. Step 6

    Completion of the study

    Upon completing the study, participants will undergo a final assessment to evaluate the overall impact of the treatment. The study is estimated to conclude by July 23, 2027.

Who can join the trial?

6 criteria

  • The participant must be at least 18 years old and meet the legal age of consent for clinical studies in their area.
  • The participant must be able to provide signed informed consent and follow the study's requirements.
  • The participant must agree to use birth control methods as required by local laws. Women who can have children must have a negative blood pregnancy test at the start and a negative urine pregnancy test before receiving the study medication.
  • The participant should not have had muscle weakness as a baby but developed weakness that gets worse with activity after the age of 16. They must have been diagnosed with acquired generalized myasthenia gravis (gMG) and meet both of the following conditions:
    • Have a history of abnormal nerve-muscle communication shown by tests like single fiber electromyography or repetitive nerve stimulation, or have tested positive for anti-muscle-specific kinase antibodies (MuSK-Ab).
    • Have a history of a positive edrophonium chloride test or show improvement in myasthenia gravis (MG) symptoms with treatments like oral acetylcholinesterase (AChE) inhibitors, plasma exchange (PLEX), immunoabsorption, or intravenous/subcutaneous immunoglobulin (IVIg/SCIg) treatment.
    • The participant must be on a stable dose of myasthenia gravis (MG) treatment before the study, which can include acetylcholinesterase (AChE) inhibitors, steroids, or nonsteroidal immunosuppressive therapies (NSISTs), either alone or in combination.

Who cannot join the trial?

4 criteria

  • Individuals who do not have a diagnosis of Acetylcholine Receptor Binding Antibody Seronegative Generalized Myasthenia Gravis cannot participate. This is a specific type of muscle weakness condition.
  • Participants must be within the specified age range for the study. If you are outside this age range, you cannot join.
  • Both males and females can participate, but if you do not identify as either, you may not be eligible.
  • If you belong to a vulnerable population, you may not be eligible. Vulnerable populations include groups that might need special protection or care.
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Investigated drugs

Efgartigimod IV is a medication being studied for its effectiveness and safety in treating adults with a specific type of myasthenia gravis, which is a condition that causes muscle weakness. This medication is given through an intravenous (IV) infusion, meaning it is administered directly into the bloodstream. The goal of the study is to see how well this medication works in improving the symptoms of myasthenia gravis in patients who do not have certain antibodies typically associated with the condition.

What is already known about the treatment

Efgartigimod – This medication is administered intravenously, meaning it is given directly into a vein. It is currently being studied in clinical trials for its effectiveness and safety in treating a condition called acetylcholine receptor binding antibody seronegative generalized myasthenia gravis. The main therapeutic use of efgartigimod is to help manage symptoms of this specific type of myasthenia gravis, a neuromuscular disorder. At the molecular level, efgartigimod works by reducing the levels of certain antibodies that interfere with normal muscle function. It is classified pharmacologically as an immunomodulatory agent, which means it helps to modify the immune system's activity.

Investigated diseases

Acetylcholine Receptor Binding Antibody Seronegative Generalized Myasthenia Gravis – This is a chronic autoimmune disorder characterized by muscle weakness and fatigue. It occurs when the body's immune system mistakenly attacks the communication between nerves and muscles, specifically targeting the acetylcholine receptors, although in this form, antibodies are not detected. The disease primarily affects voluntary muscles, leading to symptoms such as drooping eyelids, difficulty swallowing, and general muscle weakness. The severity of muscle weakness can vary, often worsening with activity and improving with rest. It is a rare condition, and its progression can be unpredictable, with periods of exacerbation and remission.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-511796-15-00Protocol codeARGX-113-2308Estimated enrolment138 patientsSponsorArgenx

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