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Study on the Effects and Safety of Efgartigimod PH20 SC for Adults with Active Idiopathic Inflammatory Myopathy

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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 Idiopathic Inflammatory Myopathy (IIM), which is a group of diseases that cause muscle inflammation and weakness. The study is investigating a treatment called efgartigimod PH20 SC, which is given as a solution for injection. This treatment is being compared to a placebo, alongside standard care treatments that help manage the immune system.

The purpose of the study is to evaluate how well efgartigimod PH20 SC works in improving the symptoms of IIM, as well as to assess its safety and how well it is tolerated by participants. Participants in the study will receive either the investigational treatment or a placebo, and their progress will be monitored over a period of time to see if there are any improvements in their condition. The study will also look at how the body processes the treatment and whether it causes any immune reactions.

Throughout the study, participants will undergo various assessments to measure changes in muscle strength and overall disease activity. These assessments will help determine the effectiveness of the treatment in providing clinical improvement for those with active IIM. The study aims to provide valuable information on whether efgartigimod PH20 SC can be a beneficial treatment option for individuals with this 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

    Joining the study

    Upon joining the study, eligibility is confirmed based on specific criteria, including a diagnosis of idiopathic inflammatory myopathy and active disease indicators.

    A signed informed consent is required to participate.

  2. Step 2

    Initial assessment

    An initial assessment is conducted to evaluate the current health status and confirm the diagnosis.

    This may include laboratory tests, electromyography, skin rash evaluation, muscle biopsy, or MRI to confirm active inflammation.

  3. Step 3

    Randomization

    Participants are randomly assigned to receive either the investigational drug efgartigimod PH20 SC or a placebo.

    This process is double-blinded, meaning neither the participant nor the study team knows which treatment is being administered.

  4. Step 4

    Treatment administration

    The treatment involves subcutaneous injections of efgartigimod PH20 SC or placebo.

    The frequency and duration of the treatment are determined by the study protocol and are administered alongside standard immunomodulatory therapy.

  5. Step 5

    Monitoring and follow-up

    Regular monitoring is conducted to assess the efficacy and safety of the treatment.

    This includes evaluating improvement scores, muscle strength, and overall disease activity through various assessments.

  6. Step 6

    Completion of study

    The study is estimated to conclude by August 2026.

    Upon completion, participants may undergo a final assessment to evaluate the overall impact of the treatment.

Who can join the trial?

13 criteria

  • Must be able to understand and agree to participate in the study, and sign a consent form.
  • Must have a confirmed or likely diagnosis of idiopathic inflammatory myopathy (IIM), which is a type of muscle inflammation with an unknown cause.
  • Must have one of the following medical histories:
    • Dermatomyositis (DM) or juvenile dermatomyositis (JDM), with the disease starting before 18 years old. For JDM, the diagnosis should be within 5 years of the study screening date.
    • Polymyositis (PM), which may include antisynthetase syndrome (ASyS).
    • Immune-mediated necrotizing myopathy (IMNM).
    • Must have active disease, shown by at least one of the following:
      • Abnormal levels of certain enzymes in the blood, such as creatine kinase (CK), aldolase, lactate dehydrogenase, aspartate aminotransaminase (AST), or alanine aminotransferase (ALT).
      • Recent electromyography (a test that checks muscle health) showing active disease.
      • Active skin rash related to dermatomyositis (DM).
      • Muscle biopsy (a small sample of muscle tissue) from the past 3 months showing active IIM.
      • Recent magnetic resonance imaging (MRI) showing active inflammation.
      • Must have muscle weakness.
      • Must be receiving a treatment for IIM that is allowed in the study.
      • Must follow local rules for contraceptive use if applicable. Women who can become pregnant must have a negative pregnancy test before starting the study treatment.

Who cannot join the trial?

10 criteria

  • Patients with any other active autoimmune disease that might interfere with the study.
  • Patients who have had a recent infection that required treatment with antibiotics or antiviral medications.
  • Patients who have received any other investigational drug within the last 30 days.
  • Patients with a history of severe allergic reactions to any of the study medications.
  • Patients who are pregnant or breastfeeding.
  • Patients with significant heart, liver, or kidney problems.
  • Patients with a history of cancer, except for certain types of skin cancer.
  • Patients who have received a live vaccine within the last 4 weeks.
  • Patients with a history of drug or alcohol abuse within the last year.
  • Patients who are unable to comply with the study procedures.
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Investigated drugs

Efgartigimod PH20 SC is a medication being studied for its potential to help people with active idiopathic inflammatory myopathy, a condition that causes muscle inflammation and weakness. This medication is designed to work by modulating the immune system, potentially reducing inflammation and improving muscle strength and function. The trial aims to assess how well this medication works, how safe it is, and how the body processes it.

What is already known about the treatment

Efgartigimod PH20 SC – This medication is administered subcutaneously, meaning it is injected under the skin. It is currently being studied in clinical trials for its effectiveness in treating active idiopathic inflammatory myopathy, a condition characterized by muscle inflammation. The drug works by modulating the immune system, specifically targeting and reducing the activity of certain antibodies that contribute to the disease. Efgartigimod belongs to the pharmacological class of immunomodulatory agents, which are used to alter the immune response in various conditions.

Investigated diseases

Idiopathic Inflammatory Myopathy – This is a group of diseases characterized by chronic muscle inflammation and weakness. The exact cause is unknown, but it involves the immune system attacking the body's own muscle tissues. Symptoms often include muscle pain, fatigue, and difficulty with movements such as climbing stairs or lifting objects. Over time, the muscle weakness can become more pronounced, affecting daily activities. The condition can vary in severity and may involve other organs, such as the skin or lungs. It is typically a long-term condition that requires ongoing management.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2024-512785-33-00Protocol codeARGX-113-2007Estimated enrolment343 patientsSponsorArgenx

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