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A Study of MAS825 in Children and Adults with Still's Disease to Test How Well It Works and How Safe It Is

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What is this trial about?

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

This study examines Still's disease, a rare inflammatory condition that causes fever, rash, and joint pain. The condition can affect both children and adults, and it involves inflammation throughout the body that can lead to various symptoms including swelling of the joints and organs. The study will test a medicine called MAS825, which is a laboratory-made protein designed to block certain substances in the body that cause inflammation. Participants will also receive glucocorticoids, which are medications commonly used to reduce inflammation and are part of the standard treatment for this condition. The purpose of the study is to see how well MAS825 works in reducing disease activity in people with Still's disease.

During the study, participants will receive MAS825 through an injection into a vein, under the skin, or into a muscle, along with their glucocorticoid treatment. The study will look at whether the treatment helps control the disease and whether it allows participants to reduce the amount of glucocorticoids they need to take. The treatment period can last for several years, during which participants will be monitored regularly to check how they are responding to the medicine.

Throughout the study, doctors will assess various aspects of the participants' health, including changes in disease activity, physical function, and any side effects that may occur. Safety will be monitored through regular checks of vital signs, heart function using an ECG, and blood tests. The study will also track whether participants experience any unwanted effects from the treatment and whether the disease becomes inactive while taking lower doses of glucocorticoids.

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

    Treatment period begins

    Upon joining the study, you will begin receiving treatment with MAS825, which is a medication designed to target specific proteins in your body called IL-1 beta and IL-18 that contribute to inflammation in Still's disease.

    The medication will be administered through one of the following methods: into a vein (intravenous), under the skin (subcutaneous), or into a muscle (intramuscular). The specific method will be determined by the study protocol.

    MAS825 is provided as a concentrated liquid that will be prepared for injection or infusion before administration.

  2. Step 2

    Ongoing monitoring and assessments

    Throughout the study, your disease activity will be regularly evaluated to determine how well the treatment is working.

    Your doctor will assess your overall condition and any changes in your symptoms.

    Regular blood tests will be performed to monitor laboratory features, including markers related to a condition called Macrophage Activation Syndrome, which can occur in Still's disease.

    Your vital signs, such as blood pressure, heart rate, and temperature, will be measured at study visits.

    An ECG (electrocardiogram), which is a test that records the electrical activity of your heart, will be performed at scheduled intervals.

    You will be asked to report any side effects or health changes you experience during the study.

  3. Step 3

    Steroid medication adjustment

    You will continue taking glucocorticoids (steroid medication such as prednisone or an equivalent) as part of your treatment.

    The dose of your steroid medication will be monitored and compared to the amount you were taking at the start of the study.

    Depending on your response to treatment, adjustments to your steroid dose may occur during the study period.

  4. Step 4

    Assessment of physical function

    You, or your parent if you are a child, will be asked to complete assessments about your physical function and daily activities.

    These assessments will help measure any changes in your ability to perform everyday tasks compared to the beginning of the study.

  5. Step 5

    Evaluation of treatment response

    Your response to treatment will be evaluated based on a composite endpoint, which means multiple factors will be considered together to determine if the treatment is effective.

    The goal is to achieve a clinical response that indicates improvement in your disease activity.

    The study will also assess whether you achieve clinically inactive disease, meaning your condition shows minimal or no signs of active inflammation while you are taking a reduced dose of steroids.

  6. Step 6

    Study completion

    The study is expected to continue until May 2029.

    Your participation will involve regular visits and assessments throughout the duration of your enrollment in the study.

    All safety information, including any adverse events or serious adverse events, will be collected and reviewed throughout the entire study period.

Who can join the trial?

4 criteria

  • You must be 1 year of age or older and have been diagnosed with Still's disease, which is a rare inflammatory condition that causes fever, rash, and joint pain
  • You must have active disease, meaning your Still's disease is currently causing symptoms and has not been fully controlled
  • You must currently need treatment with glucocorticoids, which are medications such as prednisone that help reduce inflammation and control your immune system
  • Both males and females can participate in this study

Who cannot join the trial?

4 criteria

  • The study does not list specific exclusion criteria in the provided information, which means the detailed reasons why someone cannot participate are not available in this document.
  • Generally, clinical trials have rules about who cannot join to protect patient safety and ensure the study results are reliable.
  • Common reasons people might not be able to join studies include having other serious health conditions, taking certain medications that could interfere with the study drug, being pregnant or breastfeeding (feeding a baby with breast milk), or having allergies to the study medication.
  • Each study has its own specific rules, and a doctor involved in the trial would review your medical history to determine if you meet all requirements.
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Investigated drugs

MAS825 is an investigational medication being studied in this trial for people with Still's disease. This is an experimental treatment that is being tested to see if it can help reduce disease activity and improve symptoms in both children and adults who have this condition. The study will look at how well the medication works and whether it is safe and well-tolerated by participants.

What is already known about the treatment

MAS825 – MAS825 is an experimental medication currently being studied in clinical trials and is not yet approved for regular medical use. It is being tested as a treatment for Still's disease, which is a rare inflammatory condition that causes fever, rash, and joint pain in both children and adults. The medication is administered under medical supervision in a clinical trial setting, and researchers are evaluating how well it works to reduce disease activity and inflammation in patients with this condition. The exact way MAS825 works in the body at the cellular level has not been publicly disclosed in detail, as it is still under investigation as part of ongoing research.

Investigated diseases

Still's Disease – Still's disease is a rare inflammatory disorder that affects the entire body. The condition causes high spiking fevers, a distinctive salmon-colored rash, and joint pain or inflammation. It can occur in children, where it is known as systemic juvenile idiopathic arthritis, or in adults as adult-onset Still's disease. The disease progresses with episodes of active inflammation that may come and go unpredictably. During flare-ups, patients experience systemic symptoms including fever, rash, sore throat, and swollen lymph nodes along with joint problems. Some patients may develop a serious complication called Macrophage Activation Syndrome, which involves excessive activation of immune cells.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2024-520208-25-00Protocol codeCMAS825J12201Estimated enrolment30 patientsSponsorNovartis Pharma AG

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