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Rituximab versus azathioprine for remission maintenance in patients with primary angiitis of the central nervous system – randomized controlled trial

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What is this trial about?

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

The trial focuses on patients with primary angiitis of the central nervous system, a rare condition in which blood vessels in the brain become inflamed, leading to headaches, weakness, vision problems, or strokes. The main goal is to find out whether one medication can keep the disease in remission better than the standard treatment.

Two medicines are being compared: an intravenous infusion of rituximab, which is given through a vein to target immune cells, and oral tablets of azathioprine, a pill that also reduces immune activity. Participants will receive the assigned medication over a period of up to two years while doctors monitor their health.

During the study, participants will have regular clinic visits, blood tests, and brain scans using MRI with contrast dye to check for any new or worsening signs of disease. The study will track how long participants stay free of relapse and record any side effects or changes in medication over the 24‑month follow‑up.

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

    Randomization

    After joining the study you will be assigned by the study team to one of two groups. the assignment is done randomly, so you will receive either the test medication or the comparison medication.

    The group assignment determines which medication you will take for the next 24 months.

  2. Step 2

    Start of maintenance therapy

    Once you are assigned to a group, you will begin the maintenance therapy that is used to keep the disease in remission.

    The therapy will continue for up to 24 months unless the study protocol requires a change.

  3. Step 3

    Medication administration

    If you are assigned to the comparison group you will take azathioprine tablets. each tablet contains 160 mg of the active substance. the tablets are taken orally, usually once a day, as directed by the study staff.

    If you are assigned to the test group you will receive rituximab by intravenous infusion. the infusion contains a total dose of 1000 mg of rituximab, prepared as a solution for infusion. the infusion is given in a clinical setting according to the schedule defined by the trial protocol.

  4. Step 4

    Regular follow‑up visits

    Throughout the 24‑month period you will attend scheduled visits with the study team. at each visit you will be asked about any new symptoms, side effects, and overall health.

    The visits also include physical examinations and collection of blood samples to monitor safety and drug levels.

  5. Step 5

    Imaging and relapse monitoring

    Periodically you will undergo magnetic resonance imaging (mri) of the brain. the scans are used to look for new or worsening lesions that could indicate a relapse of the disease.

    Relapse is defined as the return or worsening of neurological symptoms that are linked to the underlying condition. any sign of relapse will be recorded by the study staff.

  6. Step 6

    Study completion

    After 24 months of therapy the study period ends for you. final assessments are performed, including evaluation of disease status, functional outcome, and any adverse events that occurred during the trial.

    The results will be used to compare the effectiveness of rituximab versus azathioprine for maintaining remission.

Who can join the trial?

7 criteria

  • Be at least 18 years old.
  • Have a confirmed diagnosis of primary angiitis of the central nervous system (PACNS), which means inflammation of the blood vessels in the brain and spinal cord.
  • The study’s review team must verify that the PACNS diagnosis is correct.
  • Be in remission (the disease is not actively causing symptoms) after the initial “induction” treatment that was used to bring the disease under control.
  • If you are a female who could become pregnant, you must use a reliable method of contraception (birth control) during the study.
  • Be able to read, understand, and sign a written informed consent form, indicating you agree to take part in the trial.
  • Have an active form of social security or health insurance that covers your medical care.

Who cannot join the trial?

9 criteria

  • Having any other type of vasculitis (inflammation of blood vessels) besides the study disease.
  • Having severe cardiac failure (the heart cannot pump blood well enough).
  • Having an acute or chronic active infection (a current infection or a long‑standing infection that is still active).
  • Having active or recent cancer (cancer that is currently present or was treated within the past five years).
  • Being pregnant or lactating (breast‑feeding).
  • Having hypersensitivity (allergy) to a monoclonal antibody or other biologic agent (lab‑made protein medicines).
  • Being thought not likely to follow the treatment plan as asked.
  • Being unable to sign a written informed consent form (the document that shows you agree to join the study).
  • Being under guardianship, conservatorship, or a court‑ordered restraint (someone else makes legal decisions for you).
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Investigated drugs

  • Azathioprine

    is an oral medication that weakens the immune system. In this study it is used as the standard treatment to help keep the disease under control after patients have been treated for the initial episode. By lowering the activity of the immune system, azathioprine aims to prevent new flare‑ups of the blood vessel inflammation in the brain.

  • Rituximab

    is a medication given by an intravenous infusion. It works by targeting a specific type of white blood cell (B‑cells) that are involved in the immune response. In the trial, rituximab is tested as a new option for maintenance therapy, with the goal of keeping the disease in remission and possibly working better than the standard azathioprine treatment.

What is already known about the treatment

  • Azathioprine

    Azathioprine is taken by mouth as film‑coated tablets, and it is an approved immunosuppressive drug used to help prevent organ rejection and treat autoimmune disorders. It is well known in medical practice and described in many clinical studies. The medicine works by slowing down the growth of immune cells that can cause inflammation. It belongs to the class of purine antimetabolite immunosuppressants.

  • Rituximab

    Rituximab is given through an intravenous infusion, and it is a licensed biologic therapy for certain cancers and autoimmune diseases. It is widely studied and listed in current medical literature. The drug targets a protein called CD20 on B‑cells, leading to their removal and reducing harmful immune activity. It is classified as an anti‑CD20 monoclonal antibody.

Investigated diseases

Primary angiitis of the central nervous system - Primary angiitis of the central nervous system is a rare inflammatory disease that affects the blood vessels of the brain and spinal cord. It causes swelling and narrowing of these vessels, which can reduce blood flow. Over time, the inflammation may create new lesions that appear on brain scans. Patients may experience new or worsening neurological symptoms such as headaches, weakness, or coordination problems as the disease becomes active. The condition can also cause small strokes or bleedings when vessels are damaged. Without treatment, the inflammation can continue to spread and involve more vessels.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2026-525394-39-00Protocol codeD25 – P043Estimated enrolment74 patientsSponsorGroupe Hospitalier Universitaire Paris Psychiatrie Et Neuroscience

sourced from the EU Clinical Trials Register and site verification

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).