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A study to evaluate the efficacy and safety of rilzabrutinib in adults with active IgG4-related disease

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What is this trial about?

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

This study focuses on individuals living with IgG4-related disease, a rare immune system disease where the body's defense system causes swelling and damage to various organs. The purpose of this study is to evaluate the effectiveness and safety of a medication called rilzabrutinib, also known as SAR444671, compared to a placebo.

Participants in the study will be randomly assigned to receive either the study medication or a placebo. During the 52-week period, the study will monitor how well the treatment works in preventing a flare, which is a sudden increase in disease symptoms or activity. The research will also look at how the medication affects the need for other treatments, such as glucocorticoids or immunomodulators, which are drugs used to lower immune system activity.

The research process

The trial runs in 2 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Study participation and medication administration

    Participation begins with the administration of either rilzabrutinib or a placebo, which is an inactive substance used for comparison.

    The administration period lasts for 52 weeks.

    The goal is to evaluate how rilzabrutinib affects IgG4-related disease, a condition where the immune system (the body's defense system) causes inflammation and swelling in various organs.

  2. Step 2

    Monitoring for disease activity

    During the 52-week period, the focus is on monitoring for any clinical disease flares, which are sudden increases in symptoms or disease activity.

    The effectiveness of the treatment is measured by the length of time spent without a flare.

    Changes in disease activity scores, which are measurements used to track the severity of the condition, are recorded from the start of the study through week 52.

Who can join the trial?

12 criteria

  • You must have a confirmed medical diagnosis of IgG4-related disease, which is a rare condition where the body's immune system causes swelling and inflammation in organs.
  • Your condition must meet specific medical scoring rules called the 2019 ACR/EULAR classification criteria, which is a standardized way doctors identify this disease using a point system.
  • You must have active disease, meaning the condition is currently causing symptoms or inflammation, in at least one organ other than the lymph nodes (the small, bean-shaped structures that are part of the immune system).
  • Your disease activity must have a score of 2 or higher on the IgG4-RD Responder Index, which is a tool used to measure how much the disease is affecting your body.
  • You must have a history of the disease affecting at least one organ or body part, excluding the lymph nodes.
  • You must have had your disease symptoms controlled for at least 2 weeks while taking a steady dose of glucocorticoids, which are steroid medicines used to reduce inflammation.
  • You must be willing to slowly reduce your dose of glucocorticoids (steroids) after you begin taking the study medication.
  • You must be willing and able to undergo regular medical imaging tests to check your disease, such as computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), or ultrasound.
  • You must be up to date on your vaccinations according to local health rules. If you receive a live vaccine (a type of vaccine that uses a weakened version of the germ), it must be given at least 30 days before the study starts.
  • Men and women participating in the study must use contraception (methods used to prevent pregnancy) in a way that follows local rules for clinical trial participants.
  • The study is open to both men and women.
  • Participants must be within the specific age range defined by the study protocols.

Who cannot join the trial?

14 criteria

  • You meet specific medical rules called the Step 2 Exclusion criteria used to classify IgG4-related disease (IgG4-RD), which is a condition where the immune system causes inflammation and scarring in various organs.
  • You have a history of drug abuse, which means using illegal drugs or using prescription drugs in a way they were not intended, within the last 12 months.
  • You have alcoholism or drink too much alcohol, defined as more than about 3 standard drinks every day.
  • You have previously taken part in studies testing rilzabrutinib or other BTK inhibitors, which are a specific type of medicine that blocks certain proteins in the immune system.
  • You have used an investigational drug, which is an experimental medicine being tested in a study, within the last 6 months or within a timeframe based on how long it takes for the drug to leave your body (known as 5 half-lives).
  • Your laboratory tests, such as blood work performed by the central lab, show abnormalities or results that are outside of the healthy range.
  • You have a history of certain types of scarring in specific parts of the body, such as the area behind the abdomen (retroperitoneal fibrosis), the tissue around the intestines (sclerosing mesenteritis), or the area in the middle of the chest (fibrosing mediastinitis), if these are the only symptoms of your disease.
  • You have active malignancy, which means an ongoing cancer, or a history of cancer within the last 5 years, unless it was a very specific type of skin cancer or cervical cancer that has been completely treated and resolved.
  • You have a known or suspected immunodeficiency, which means your immune system does not work properly and you are more likely to get sick. This includes having opportunistic infections, which are illnesses that primarily affect people with weakened immune systems, or having infections that happen too often or last too long.
  • You have a history of serious infections that could come back, and you have recovered from them less than 4 weeks before the first dose of the study medicine, or you currently have a moderate to severe infection.
  • You have liver disease that is not caused by your IgG4-related disease.
  • You have conditions that might prevent your body from properly absorbing the medicine, such as refractory nausea and vomiting (feeling sick to your stomach that does not go away), malabsorption (the inability to absorb nutrients from food), having a biliary shunt (a tube used to help bile flow), having had bariatric surgery (weight loss surgery), or having a bowel resection (removal of part of the intestine).
  • You have a history of a solid organ transplant, which means you have received a transplanted organ like a kidney or liver.
  • You have a major surgical procedure planned during the time you would be in the study.
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Investigated drugs

Rilzabrutinib is a medication being studied to see if it can help prevent flares in adults with active IgG4-related disease.

What is already known about the treatment

  • Rilzabrutinib

    This medication is an experimental drug currently being studied in late-stage clinical trials to treat rare immune system disorders like IgG4-related disease. It is typically administered as an oral tablet that is swallowed by the patient. As a Bruton's tyrosine kinase (BTK) inhibitor, it works by blocking a specific protein inside certain immune cells, which helps prevent them from causing excessive inflammation and tissue damage. This drug belongs to a class of medicines known as kinase inhibitors that aim to calm an overactive immune response.

  • Placebo

    This is an inactive substance that looks exactly like the study medication but contains no active medicinal ingredients. It is administered using the same method as the test drug, such as an oral tablet, to ensure the study remains fair and unbiased. In clinical research, a placebo is used as a baseline to compare how well the actual drug works compared to no treatment at all. It has no therapeutic effect and is not used to treat any medical conditions.

Investigated diseases

IgG4-related disease - This is a condition where the immune system causes swelling and inflammation in various organs and tissues. The process often involves the buildup of certain types of cells that can lead to the formation of lumps or masses. These changes can affect many parts of the body, such as the salivary glands, pancreas, or lymph nodes. As the condition progresses, the inflammation may cause organs to become enlarged or scarred. This swelling can eventually interfere with how these organs function normally.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-521398-15-00Protocol codeEFC17359Estimated enrolment144 patientsSponsorSanofi-Aventis Recherche & Developpement

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