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Study of benralizumab compared to placebo for treatment of patients with Hypereosinophilic Syndrome (HES)

Fast replyRegistered drugNo placebo
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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 patients with Hypereosinophilic Syndrome (HES), a condition where there are persistently high levels of certain white blood cells called eosinophils in the blood, which can cause damage to various organs. The study will test a medication called benralizumab (Fasenra), which is given as an injection under the skin, to see if it can help control HES symptoms and prevent disease flares.

The research aims to determine how effective benralizumab is in delaying or preventing HES flares compared to placebo. During the study, which lasts 24 weeks, participants will receive either benralizumab or placebo through an injection under the skin using a pre-filled syringe. After this initial period, there is an opportunity to continue treatment in an open-label extension phase where all participants receive the active medication.

Throughout the study, doctors will monitor participants' symptoms, particularly looking for signs of disease worsening or flares. They will also track changes in blood cell counts, fatigue levels, and overall health. The medication being tested is designed to reduce the number of eosinophils in the blood, which may help control the symptoms of HES and prevent organ damage.

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 period - double-blind phase

    You will be randomly assigned to receive either benralizumab (30 mg) or placebo through subcutaneous injection

    The treatment will continue for 24 weeks during this phase

    Your condition will be monitored for signs of HES worsening (Hypereosinophilic Syndrome) or flares

  2. Step 2

    Monitoring and assessments

    Regular blood tests will be performed to measure your eosinophil count (a type of white blood cell)

    Your fatigue levels will be assessed using a standardized questionnaire

    Your overall health and quality of life will be evaluated using specific forms

    Any symptoms or changes in your condition will be documented

  3. Step 3

    Open-label extension period

    After the initial 24-week period, you may continue treatment in the open-label extension phase

    During this phase, all participants will receive benralizumab

    Your condition will continue to be monitored for safety and effectiveness

    Regular assessments of symptoms and laboratory tests will continue

  4. Step 4

    Safety monitoring

    Throughout the study, you will be monitored for any side effects

    Regular checks of vital signs will be performed

    Laboratory tests will be conducted to ensure your safety

    Any changes in your health status will be documented and evaluated

Who can join the trial?

10 criteria

  • Must be at least 12 years old at the time of signing the consent form
  • Must provide signed and dated written informed consent (or have legal representative consent)
  • Must have a confirmed diagnosis of Hypereosinophilic Syndrome (HES) with: - Blood tests showing high levels of eosinophils (>1500 cells/μL) on two separate occasions at least 1 month apart - Evidence of organ problems caused by high eosinophil levels
  • Must test negative for a specific genetic mutation called FIP1L1-PDGFRA
  • Must be on stable HES treatment for at least 4 weeks before the first study visit
  • Must have either: - Current signs of HES getting worse, or - History of at least 2 HES flares in the past 12 months that required increased treatment
  • Must have an eosinophil count of at least 1000 cells/μL at first visit
  • Must respond to corticosteroid treatment (showing reduced eosinophil counts after taking prednisone/prednisolone)
  • For women who can become pregnant: - Must use effective birth control during the study and for 12 weeks after - Must have a negative pregnancy test at first visit
  • For women who cannot become pregnant, must either: - Have had specific surgical procedures (hysterectomy or removal of ovaries/fallopian tubes), or - Be post-menopausal (no menstrual periods for at least 12 months)

Who cannot join the trial?

15 criteria

  • Age under 12 years old
  • Known allergic reactions to benralizumab or similar medications
  • Pregnancy or breastfeeding
  • Active or untreated parasitic infections (infections caused by parasites)
  • Participation in other clinical trials within the last 30 days
  • Severe liver disease (problems with liver function)
  • Severe kidney disease (problems with kidney function)
  • Active cancer or ongoing cancer treatment
  • Uncontrolled heart conditions
  • History of severe allergic reactions
  • Recent major surgery (within last 3 months)
  • Active infections requiring antibiotics
  • Use of other biological treatments for HES (Hypereosinophilic Syndrome) in the past 4 months
  • Mental conditions that could interfere with following study procedures
  • Drug or alcohol abuse within the past year
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Investigated drugs

Benralizumab is a medication used to treat patients with Hypereosinophilic Syndrome (HES), a rare blood disorder. It works by targeting and reducing specific white blood cells called eosinophils that are present in unusually high numbers in HES patients. This medication is designed to help prevent disease flares and worsening of symptoms in people with HES. It is administered through injections.

What is already known about the treatment

Benralizumab - A biological medication administered through subcutaneous injection that belongs to the class of monoclonal antibodies specifically designed to treat conditions characterized by high levels of eosinophils in the blood. This medication works by targeting and binding to the interleukin-5 receptor (IL-5R) on eosinophils, leading to their reduction in the bloodstream, which is particularly beneficial in treating Hypereosinophilic Syndrome (HES). Benralizumab represents a targeted therapeutic approach in immunology, offering a treatment option for patients with HES by modulating the immune system's response and reducing inflammation caused by elevated eosinophil levels.

Investigated diseases

Hypereosinophilic Syndrome (HES) - A blood disorder characterized by persistently elevated levels of eosinophils (a type of white blood cell) in the blood and tissues. The condition occurs when the body produces too many eosinophils without a known cause. These elevated eosinophils can gradually cause damage to various organs, including the heart, lungs, skin, and nervous system. Patients may experience different symptoms depending on which organs are affected, such as fatigue, skin rashes, breathing difficulties, or numbness in limbs. The severity of symptoms can vary greatly among individuals, and the condition can progress at different rates.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-510455-28-00Protocol codeD3254C00001Estimated enrolment113 patientsSponsorAstraZeneca AB

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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).