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A study to evaluate the safety and effectiveness of empasiprubart and efgartigimod alfa in patients with 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 study is being conducted to evaluate the safety and effectiveness of different treatment approaches for Myasthenia Gravis. This is a rare autoimmune disease where the body's immune system mistakenly attacks the connection between nerves and muscles, leading to muscle weakness. Specifically, this research focuses on a subtype called AChR-Ab Seropositive Generalized Myasthenia Gravis, which means the disease is present throughout the body and certain antibodies, known as acetylcholine receptor antibodies, can be detected in the blood.

The research involves the use of two medications: efgartigimod alfa and empasiprubart. Both of these are administered through an IV infusion, which is a method of delivering medication directly into a vein. Some participants will receive efgartigimod alfa alone, while others will receive empasiprubart as an additional treatment added to their current efgartigimod alfa therapy. This approach is intended for individuals who have experienced only a partial improvement in their symptoms while using the first medication.

During the study, participants will follow a specific treatment schedule to observe how the medications affect their condition and overall health. Monitoring will include checking vital signs and conducting an ECG, which is a test that records the electrical activity of the heart, to ensure the treatments are tolerated well. The study aims to observe changes in how much the disease impacts daily activities and the severity of muscle weakness over time.

The research process

The trial runs in 3 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Start of the study

    The participation in the study begins with the administration of efgartigimod alfa. this medication is given as an intravenous infusion, which means it is delivered directly into a vein.

    The dose for efgartigimod alfa is 1200 mg.

  2. Step 2

    Addition of therapy

    The medication empasiprubart is added to the current treatment. this is also administered via intravenous infusion.

    This treatment is used as an add-on therapy, meaning it is given alongside the efgartigimod alfa.

  3. Step 3

    Monitoring and evaluation

    Throughout the study, vital signs (such as blood pressure and heart rate), electrocardiograms (tests that check the heart's electrical activity), and laboratory parameters (blood tests) are monitored.

    The effects on myasthenia gravis symptoms are tracked using specific scores, such as the myasthenia gravis activities of daily living (mg-adl) score and the quantitative myasthenia gravis (qmg) score, to measure how much the disease impacts daily tasks and physical strength.

Who can join the trial?

7 criteria

  • You must be at least 18 years old or the legal age required to agree to participate in medical studies in your area.
  • You must have been diagnosed with Myasthenia Gravis, a condition that affects how muscles work, with symptoms that match the requirements set by the study doctor.
  • If you are already taking medicines for your condition, such as corticosteroids (steroid medicines that reduce swelling and immune activity), nonsteroidal immunosuppressive drugs (medicines that lower the activity of your immune system), or acetylcholinesterase inhibitors (medicines that help improve communication between nerves and muscles), your dose must be stable, meaning it has not changed recently.
  • You must test seropositive for anti-acetylcholine receptor antibodies, which means your blood contains specific proteins that mistakenly attack the parts of your nerves that control muscle movement.
  • You must have a confirmed diagnosis of generalized Myasthenia Gravis, which is a form of the disease that affects many different muscles throughout the body.
  • Your disease severity must be classified as MGFA Class II, III, IVa, or IVb, which is a scale used by doctors to measure how much the disease affects your muscle strength.
  • You must have proof of vaccination against certain bacteria, specifically Neisseria meningitidis and Streptococcus pneumoniae, within the last 5 years, or you must be willing to get these vaccines at least 14 days before starting the study medication.

Who cannot join the trial?

6 criteria

  • You have a known autoimmune disease, which is a condition where your body's immune system mistakenly attacks your own healthy cells, or any other medical problem that could make it hard to measure your symptoms or put you at extra risk.
  • Your condition is classified as MGFA Class V, which is the most severe stage of Myasthenia Gravis.
  • You have been diagnosed with systemic lupus erythematosus (SLE), a chronic disease where the immune system attacks various parts of the body like skin, joints, or organs.
  • You have any known complement deficiency, which means your body lacks certain proteins in the immune system that help fight infections.
  • You are currently taking a complement inhibitor (a medicine that stops part of the immune system) or have taken zilucoplan or eculizumab within the last 2 months, or ravulizumab within the last 6 months.
  • You have been found to be refractory to efgartigimod, meaning the medicine efgartigimod did not work for you because you did not see an improvement of at least 2 points on the MG-ADL score, which is a scale used to measure how much your daily activities are affected by your symptoms.
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Investigated drugs

  • Empasiprubart

    is an experimental medicine given through a vein (IV infusion) that is being studied to see if it can help improve symptoms in people with myasthenia gravis, specifically when used alongside another treatment.

  • Efgartigimod alfa

    is a treatment given through a vein (IV infusion) used to help manage myasthenia gravis by targeting specific parts of the immune system.

What is already known about the treatment

  • Empasiprubart

    This medication is a concentrated liquid that is administered through a slow drip into a vein. Currently being studied in clinical trials, it is classified as a monoclonal antibody designed to treat autoimmune conditions like myasthenia gravis. It works by specifically targeting and attaching to certain harmful proteins in the immune system to prevent them from causing damage.

  • Efgartigimod alfa

    This medicine is provided as a liquid solution that is delivered directly into the bloodstream through a vein. It is an approved orphan drug used primarily to treat rare autoimmune diseases such as myasthenia gravis. It belongs to a class of drugs called neonatal Fc receptor blockers, which work by lowering the levels of harmful antibodies in the body to reduce muscle weakness.

Investigated diseases

Generalized Myasthenia Gravis - This is an autoimmune disorder where the body's immune system mistakenly attacks the communication points between nerves and muscles. This attack leads to weakness in various muscle groups throughout the body. The condition typically causes fluctuating muscle weakness that worsens with physical activity and improves with rest. Symptoms often involve the eyes, face, throat, and limbs. As the disease progresses, the weakness can spread to different parts of the body.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-522492-28-00Protocol codeARGX-999-2-MG-20001Estimated enrolment70 patientsSponsorArgenx

sourced from the EU Clinical Trials Register and site verification

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