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Phase 1b study of empasiprubart in adults with multifocal motor neuropathy to assess nerve morphology by ultrasound

Verified siteInvestigationalNo placebo
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What is this trial about?

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

The study examines adults who have Multifocal Motor Neuropathy, a rare disorder in which the nerves that control muscle movement become damaged, causing weakness. The investigational medicine being tested is empasiprubart, administered by an intravenous infusion (a medicine delivered directly into a vein). Researchers will use ultrasound imaging to look at the size and shape of certain nerves, such as the median nerve in the forearm and the brachial plexus near the shoulder, to see whether the treatment changes the appearance of these nerves.

The purpose of the study is to evaluate the effect of empasiprubart on nerve morphology. Participants will receive the infusion at scheduled visits and undergo ultrasound scans and simple functional tests over about six months. The functional tests include hand strength and speed tasks, and questionnaires that measure daily abilities. Blood samples will be taken to check drug levels and safety, and any side effects or changes in routine medical tests such as heart rhythm recordings (ECG) will be recorded.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial Study Visit

    You attend the first study visit after you have agreed to participate. The study staff confirm that you have Multifocal Motor Neuropathy, a rare nerve disorder, and collect basic health information.

  2. Step 2

    Baseline Assessments

    A series of measurements are taken before any medication is given. These include ultrasound images of the median nerve and brachial plexus to assess nerve size, strength tests for both hands, a questionnaire called MMN‑RODS to evaluate daily function, and a standard scale to rate muscle strength (mMRC‑14).

    Blood samples are drawn to measure the natural level of the protein C2 and to establish a baseline for future safety checks.

  3. Step 3

    First Administration of empasiprubart

    You receive empasiprubart by intravenous infusion. The medication is supplied as a concentrate for solution for infusion and is delivered through a vein. The specific dose and infusion time are not detailed in the study information, but the medication is given only once at the start of the treatment period.

  4. Step 4

    Follow‑Up Visits and Ongoing Assessments

    You return for regular visits over a period of 24 weeks. At each visit, the study team repeats the ultrasound imaging of the median nerve and brachial plexus to track changes in nerve size.

    Strength tests for both hands, the MMN‑RODS questionnaire, and the mMRC‑14 scale are performed again to monitor functional changes.

    Blood is drawn to measure the concentration of empasiprubart and to check levels of free C2 and total C2.

    Standard safety checks are performed, including laboratory tests, vital‑sign measurements, and an electrocardiogram (ECG) to record heart rhythm.

  5. Step 5

    Primary Endpoint Evaluation at Week 24

    At the 24‑week visit, the main study outcome is measured. The change in nerve cross‑sectional area (CSA) compared with the baseline is calculated from the ultrasound images of the median nerve and brachial plexus.

  6. Step 6

    Safety Monitoring Throughout the Study

    At every visit, you are asked about any new symptoms or side effects. The study records any adverse events, serious adverse events, and events of special interest. Laboratory results, vital signs, and ECG findings are reviewed to ensure safety.

  7. Step 7

    Study Completion

    After the final assessments, the study concludes for you. All collected data are retained for analysis, and you are thanked for your contribution.

Who can join the trial?

6 criteria

  • Be at least 18 years old.
  • Have a diagnosis of Multifocal Motor Neuropathy (MMN), which is a rare condition that affects the nerves that control muscle movement.
  • Score 90 or lower on the MMN-RODS test, a questionnaire that measures how the disease impacts daily activities.
  • Show nerve thickening on an ultrasound exam of at least one nerve; ultrasound is an imaging test that uses sound waves to look at nerves.
  • Be either male or female (any gender).
  • Be eligible even if considered a vulnerable individual, meaning extra care is taken to protect participants who may need additional safeguards.

Who cannot join the trial?

1 criterion

  • Anyone who has a known autoimmune disease (a condition where the immune system mistakenly attacks the body’s own tissues) or any other health problem that the doctor believes could make it difficult to accurately see how the study drug affects Multifocal Motor Neuropathy or could place the person at undue risk cannot take part in the trial.
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Investigated drugs

ARGX-117 (empasiprubart)
This is an experimental medicine being tested for the first time in people with multifocal motor neuropathy. It is given through an IV infusion, which means it is slowly delivered into a vein using a thin tube. The drug is supplied as a concentrate that is mixed with fluid before it is infused. In this study, researchers are looking to see how the medicine changes the appearance of nerves when they are examined with ultrasound. Because it is a new treatment for a rare condition, it has been granted orphan‑drug status, which helps support its development.

What is already known about the treatment

Empasiprubart - Empasiprubart is given by intravenous infusion using a concentrate that is mixed with saline before it is delivered through a vein. It is an orphan drug that is still in early clinical testing (Phase 1b) and has not yet been approved for general use, so information about it is limited to trial reports. The medication is being studied for the treatment of multifocal motor neuropathy, a rare condition that causes weakness in the arms and legs. It works by attaching to a specific protein that contributes to nerve damage, reducing the immune attack on nerves, and it is classified as a biologic immune‑modulating antibody.

Investigated diseases

Multifocal Motor Neuropathy - Multifocal Motor Neuropathy is a rare disorder that primarily affects the motor nerves, leading to weakness in the arms and legs. The condition develops gradually, with symptoms often starting in one limb and then spreading to other areas. Nerve damage causes reduced muscle strength but typically does not affect sensation. Over time, the weakness may become more widespread, making everyday tasks increasingly difficult. The disease progresses at varying rates, with some individuals experiencing slow changes while others notice faster declines in muscle function.
Trial detailsLast updated 29 Oct 2026
Age18+ yearsPhasePhase ITrial ID2026-525171-20-00Protocol codeARGX-117-8-MMN-1001Estimated enrolment37 patientsSponsorArgenx

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