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A Study of ANX005 for Patients Recently Diagnosed with Guillain-Barré Syndrome to Evaluate How the Drug Works in the Body and Its Safety

Verified siteInvestigationalNo placebo
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What is this trial about?

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

This study involves people with Guillain-Barré syndrome, a condition where the body's defense system mistakenly attacks the nerves, leading to muscle weakness and sometimes paralysis. The treatment being tested is ANX005, also known as tanruprubart, which is a laboratory-made protein designed to work against a specific part of the body's defense system called C1q. This medicine is given once through a vein over a period of time, which is called an intravenous infusion. The dose used in this study is 30 milligrams for each kilogram of body weight.

The purpose of this study is to learn how the body processes ANX005, how it affects certain proteins and defense system activity in the blood, and whether it is safe and helpful for people with Guillain-Barré syndrome. The study will look at how the medicine moves through the body and how long it stays there, as well as how it changes the levels of C1q protein and the activity of the complement pathway, which is part of the body's defense system. The study will also measure changes in muscle strength using a scoring system.

Participants in this study will receive a single dose of ANX005 and will be monitored for several weeks afterward. During this time, blood samples will be collected to measure the levels of the medicine and to see how it affects certain proteins in the blood. The study will also track improvements in muscle strength and overall ability to move and function. All participants will know they are receiving the active treatment, as this is not a comparison study with placebo. The study is expected to last until mid-2026.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial treatment administration

    On the first day of the study, you will receive a single dose of the study medication called ANX005.

    The dose will be 30 milligrams per kilogram of your body weight.

    The medication will be given through an intravenous infusion, which means it will be delivered directly into your vein through a needle over a period of time.

    This medication is a type of antibody that targets a specific protein in your body called C1q, which is involved in the immune system response.

    You must have started experiencing weakness related to Guillain-Barré syndrome no more than 10 days before receiving this infusion.

  2. Step 2

    Monitoring period through week 2

    During the first two weeks after receiving the medication, your medical team will closely monitor how the medication moves through your body and how it affects certain proteins and immune system activity in your blood.

    Blood samples will be taken to measure the levels of the study medication in your blood.

    Blood samples will also be taken to measure changes in free C1q protein concentration, which is the protein that the medication targets.

    Additional blood samples will measure changes in complement pathway activity, which is part of your immune system's response.

  3. Step 3

    Assessment at week 1

    At the end of the first week, your muscle strength will be assessed using the Medical Research Council sumscore.

    This assessment measures the strength of different muscle groups in your body.

    The results will be compared to your muscle strength at the beginning of the study to determine if there have been any changes.

  4. Step 4

    Follow-up visits after hospitalization

    After you are discharged from the hospital, you will need to attend outpatient follow-up visits.

    These visits are necessary to complete all required evaluations and procedures as specified in the study.

    The exact schedule and duration of these follow-up visits will be provided to you during the study.

Who can join the trial?

8 criteria

  • You must be between 12 and 85 years old at the time you sign the consent form
  • You must have a diagnosis of Guillain Barre Syndrome, which is a condition where the body's immune system attacks the nerves, according to specific medical guidelines
  • Your weakness related to Guillain Barre Syndrome must have started no more than 10 days before the first treatment
  • You must have a certain level of disability score of 3, 4, or 5, which measures how much the condition affects your ability to move and function
  • If you are female, you must be past menopause, which means no monthly periods for at least 12 months, or have had surgery to prevent pregnancy; OR if you can become pregnant, you must use an acceptable form of birth control during the study and for at least 30 days after receiving the study medication
  • You must agree not to use illegal drugs during the study and agree to drug testing at the beginning and at any time if drug use is suspected
  • You must be able to follow all study requirements and complete all visits and tests, including visits after leaving the hospital and follow-up appointments at the clinic
  • You must be able to understand and sign the consent form, or your legal representative or guardian must be able to do so on your behalf

Who cannot join the trial?

3 criteria

  • The study does not list specific reasons why patients cannot participate in the trial based on the provided information.
  • General exclusion criteria, which are reasons that would prevent someone from joining a study, have not been detailed in the available data.
  • Patients interested in this study should discuss their individual medical situation with their doctor to determine if they are suitable candidates for participation.
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Investigated drugs

ANX005 is an investigational medication being studied for the treatment of Guillain-Barré Syndrome. This is an experimental drug that is being tested to see how the body processes it, how it works in the body, and whether it is safe and effective for people who have recently been diagnosed with this condition. In this study, participants will receive a single dose of this medication.

What is already known about the treatment

ANX005 – ANX005 is an experimental medication currently being studied in clinical trials and is not yet approved for general medical use. It is administered as a single intravenous infusion at a dose of 30 mg per kilogram of body weight, delivered directly into the bloodstream through a vein. This medication is being investigated as a potential treatment for Guillain-Barré Syndrome, a rare condition where the body's immune system attacks the nerves, causing muscle weakness and sometimes paralysis. ANX005 works by blocking a specific protein in the immune system called C1q, which helps reduce the harmful immune response that damages the nerves in this disease.

Investigated diseases

Guillain-Barré Syndrome – Guillain-Barré Syndrome is a rare condition in which the body's immune system mistakenly attacks the nerves outside the brain and spinal cord. The disorder typically begins with weakness and tingling sensations in the legs that can spread to the upper body and arms. As the condition progresses, the muscle weakness can become more severe and may affect both sides of the body. In many cases, the symptoms worsen over a period of days to weeks before reaching their most severe point. The nerve damage occurs because the immune system strips away the protective covering of the nerves, which slows down or blocks the signals traveling through them. Most people experience the most significant symptoms within the first few weeks after onset.
Trial detailsLast updated 11 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-522664-32-00Protocol codeANX005-GBS-05Estimated enrolment35 patientsSponsorAnnexon Inc.

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