Completed

A Multicenter, Double-blind, Placebo-controlled, Study to to Evaluate the Corticosteroid- Sparing Effects of Mepolizumab in Subjects With Hypereosinophilic Syndromes (HES) and Evaluate Efficacy and Safety of Mepolizumab in Controlling the Clinical Signs and Symptoms of Subjects With HES

0 criteria met from your profileSee at a glance how your profile meets each eligibility criteria.
What is being tested

Data Collection

Who is being recruted

Disease
+4

+ Eosinophilia
+ Hematologic Diseases
From 18 to 75 Years
See all eligibility criteria
How is the trial designed

Treatment Study

Phase 3
Interventional
Study Start: March 2004
See protocol details

Summary

Principal SponsorGlaxoSmithKline
Last updated: January 14, 2026
Sourced from a government-validated database.Claim as a partner
Study start date: March 23, 2004Actual date on which the first participant was enrolled.

A Multicenter, Randomized, Double-blind, Placebo-controlled, Parallel Group Phase III Study to Evaluate Corticosteroid-reduction and -sparing effects of Mepolizumab 750 mg intravenously in Subjects with Hypereosinophilic Syndromes (HES) and to evaluate the Efficacy and Safety of Mepolizumab in controlling the Clinical Signs and Symptoms of HES over Nine Months

Official TitleA Multicenter, Double-blind, Placebo-controlled, Study to to Evaluate the Corticosteroid- Sparing Effects of Mepolizumab in Subjects With Hypereosinophilic Syndromes (HES) and Evaluate Efficacy and Safety of Mepolizumab in Controlling the Clinical Signs and Symptoms of Subjects With HES 
NCT00081445NCT00086658
Principal SponsorGlaxoSmithKline
Last updated: January 14, 2026
Sourced from a government-validated database.Claim as a partner

Protocol

This section provides details of the study plan, including how the study is designed and what the study is measuring.
Design Details
86 patients to be enrolledTotal number of participants that the clinical trial aims to recruit.
Treatment Study
These studies test new ways to treat a disease, condition, or health issue. The goal is to see if a new drug, therapy, or approach works better or has fewer side effects than existing options.

How participants are assigned to different groups/arms
In this clinical study, participants are placed into groups randomly, like flipping a coin. This ensures that the study is fair and unbiased, making the results more reliable. By assigning participants by chance, researchers can better compare treatments without external influences.

Other Ways to Assign Participants
Non-randomized allocation: Participants are assigned based on specific factors, such as their medical condition or a doctor's decision.
None (Single-arm trial): If the study has only one group, all participants receive the same treatment, and no allocation is needed.

How treatments are given to participants
Participants are divided into different groups, each receiving a specific treatment at the same time. This helps researchers compare how well different treatments work against each other.

Other Ways to Assign Treatments
Single-group assignment: Everyone gets the same treatment.
Cross-over assignment: Participants switch between treatments during the study.
Factorial assignment: Participants receive different combinations of treatments.
Sequential assignment: Participants receive treatments one after another in a specific order, possibly based on individual responses.
Other assignment: Treatment assignment does not follow a standard or predefined design.

How the interventions assigned to participants is kept confidential
Neither participants nor researchers know who is receiving which treatment. This is the most rigorous way to reduce bias, ensuring that expectations do not influence the results.

Other Ways to Mask Information
Open-label: Everyone knows which treatment is being given.
Single-blind: Participants do not know which treatment they are receiving, but researchers do.
Triple-blind: Participants, researchers, and outcome assessors do not know which treatment is given.
Quadruple-blind: Participants, researchers, outcome assessors, and care providers all do not know which treatment is given.

Eligibility

Researchers look for people who fit a certain description, called eligibility criteria: person's general health condition or prior treatments.
Conditions
Criteria
Any sexBiological sex of participants that are eligible to enroll.
From 18 to 75 YearsRange of ages for which participants are eligible to join.
Healthy volunteers not allowedIf individuals who are healthy and do not have the condition being studied can participate.
Conditions
Pathology
Disease
Eosinophilia
Hematologic Diseases
Leukocyte Disorders
Pathologic Processes
Syndrome
Hypereosinophilic Syndrome
Criteria

Inclusion criteria: * Documented history of Hypereosinophilic Syndrome (HES) * Eosinophil count greater than 1500 cells for 6 months * Signs and symptoms of organ system involvement * No evidence of parasitic, allergic or other causes of eosinophilia after comprehensive evaluation. * Achieve and maintain a stable prednisone (corticosteroid) dose prior to starting study medication. * Not pregnant or nursing. Exclusion criteria: * Churg-Strauss Syndrome * Wegener's Granulomatosis * Lymphoma, hematological malignancy, advanced and metastatic solid tumors * Chemotherapy, radiotherapy or interleukin 2 treatment.

Study Plan

Find out more about all the medication administered in this study, their detailed description and what they involve.
Study Objectives
Study Objectives
Primary Objectives

Secondary Objectives

Study Centers

These are the hospitals, clinics, or research facilities where the trial is being conducted. You can find the location closest to you and its status.
This study has 29 locations
Suspended
GSK Investigational SiteSan Diego, United StatesSee the location
Suspended
GSK Investigational SiteDenver, United States
Suspended
GSK Investigational SiteBethesda, United States
Suspended
GSK Investigational SiteBoston, United States
Completed29 Study Centers
;