The Lancet AUGUST 18, 2012

Mepolizumab for Severe Eosinophilic Asthma (DREAM)

Ian D. Pavord, Sven Korn, Peter Howarth, et al.

Bottom Line

The DREAM trial demonstrated that intravenous mepolizumab significantly reduces the frequency of clinically significant exacerbations in patients with severe, refractory, eosinophilic asthma compared to placebo.

Key Findings

1. Mepolizumab treatment at doses of 75 mg, 250 mg, and 750 mg resulted in significant reductions in the annual rate of clinically significant asthma exacerbations compared to placebo: 48% reduction (rate 1.24, p<0.0001) for 75 mg, 39% reduction (rate 1.46, p=0.0005) for 250 mg, and 52% reduction (rate 1.15, p<0.0001) for 750 mg, relative to the 2.40 rate in the placebo group.

2. The reduction in exacerbation frequency was independent of a clear dose-response relationship among the three investigated intravenous doses.

3. Treatment with mepolizumab was associated with a decrease in emergency department visits and hospitalizations related to asthma exacerbations.

4. No significant improvements were observed in lung function (FEV1) or standard asthma control scores across the treatment groups.

5. The safety profile of mepolizumab was generally comparable to placebo, with no evidence of increased serious adverse events or treatment-related deaths.

Study Design

Design

RCT

Double-Blind

Sample

621

Patients

Duration

52 wk

Median

Setting

Multicenter, 13 countries

Population Patients aged 12-74 years with severe, refractory asthma, a history of ≥2 exacerbations requiring oral corticosteroids in the previous year, and evidence of eosinophilic inflammation.

Intervention Intravenous mepolizumab (75 mg, 250 mg, or 750 mg) every 4 weeks for 13 cycles.

Comparator Placebo (100 mL 0.9% NaCl) every 4 weeks.

Outcome Annual rate of clinically significant asthma exacerbations, defined as episodes requiring systemic corticosteroids, hospital admission, or emergency department visits.

Study Limitations

• The study did not demonstrate a dose-response relationship, making it difficult to define an optimal therapeutic dose from this trial alone.

• The trial showed no significant benefit regarding secondary endpoints such as FEV1 or asthma symptom control scores, suggesting it does not necessarily improve baseline asthma control metrics.

• The results were specifically limited to a highly selected population with severe, eosinophilic-driven disease, potentially limiting generalizability to broader asthma populations.

• The trial evaluated intravenous administration, whereas modern clinical practice primarily utilizes subcutaneous delivery.

Clinical Significance

DREAM provided pivotal evidence that targeting interleukin-5 (IL-5) with a monoclonal antibody is an effective strategy for preventing exacerbations in patients with severe eosinophilic asthma. This study established the feasibility of phenotype-driven therapy, moving beyond one-size-fits-all approaches in asthma management and setting the foundation for the regulatory approval of biological agents in this high-risk population.

Historical Context

Prior to the DREAM trial, treatment options for severe, refractory asthma were largely limited to high-dose corticosteroids, which carried significant side effects. DREAM represented a landmark success in the application of precision medicine, demonstrating that identifying specific biological markers—in this case, eosinophilic inflammation—could predict response to targeted interleukin-5 inhibition, a paradigm that has since defined the current era of asthma biologics.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

Mepolizumab is a monoclonal antibody that targets IL-5. Based on the DREAM trial, what is the specific physiological role of IL-5 in the pathogenesis of the asthma subtype studied, and how does neutralizing it lead to fewer exacerbations?

Key Response

IL-5 is the primary cytokine responsible for the growth, differentiation, recruitment, activation, and survival of eosinophils. In the 'eosinophilic phenotype' of asthma, these cells release proinflammatory mediators (like major basic protein and leukotrienes) that cause airway damage and hyperresponsiveness. By binding to IL-5, mepolizumab prevents it from interacting with the IL-5 receptor on eosinophils, leading to a profound reduction in blood and sputum eosinophilia, thereby cooling the underlying inflammatory driver of acute asthma attacks.

Resident

A patient with severe asthma requires high-dose ICS-LABA and has had two exacerbations in the last year. Following the DREAM trial's inclusion criteria, which specific biomarkers would you check to determine if they are a candidate for mepolizumab therapy?

Key Response

The DREAM trial used 'evidence of eosinophilic inflammation' as a key entry criterion. Clinicians should look for a blood eosinophil count of ≥150 cells/μL at the time of screening or ≥300 cells/μL in the past year, or a sputum eosinophil count of ≥3%, or an exhaled nitric oxide (FeNO) level of ≥50 ppb. Identifying these biomarkers allows for the transition from non-specific asthma management to targeted biologic therapy.

Fellow

The DREAM trial demonstrated a significant reduction in exacerbations but did not show a corresponding significant improvement in FEV1 across the mepolizumab arms. How does this 'dissociation' between exacerbation risk and airflow obstruction inform your understanding of the drug’s utility in severe refractory asthma?

Key Response

This dissociation suggests that mepolizumab primarily addresses the inflammatory pathways responsible for acute inflammatory 'surges' (exacerbations) rather than the fixed airway remodeling or acute bronchospastic components that dictate baseline FEV1. For fellows, this highlights that the primary clinical goal of anti-IL-5 therapy is 'stability and prevention' rather than 'symptom reversal' or lung function normalization, requiring careful management of patient expectations.

Attending

The DREAM trial compared three different intravenous doses of mepolizumab (75mg, 250mg, and 750mg) and found similar efficacy across all three. What does this suggest about the IL-5 pathway's threshold, and how did this influence the eventual dosing of the subcutaneous formulation?

Key Response

The lack of a dose-response relationship suggests that the IL-5 pathway is effectively saturated even at the lowest dose tested (75mg IV). This pharmacodynamic ceiling effect indicated that higher doses do not provide additional clinical benefit for exacerbation reduction. This insight paved the way for the MENSA trial and the eventual approval of the 100mg subcutaneous dose, which achieves similar systemic exposure to the 75mg IV dose used in DREAM, optimizing the benefit-to-risk and cost-effectiveness ratios.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

The DREAM study utilized an 'enrichment' design. Critically evaluate how this strategy impacts the internal validity versus the generalizability (external validity) of the study's findings regarding mepolizumab's efficacy.

Key Response

By specifically recruiting patients with biomarkers of eosinophilic inflammation, the researchers maximized the likelihood of observing a treatment effect (high internal validity), effectively proving the 'mechanism' of the drug in the intended target. However, this enrichment limits the generalizability to the broader severe asthma population—specifically those with neutrophilic or paucigranulocytic endotypes—who might represent a significant portion of 'refractory' cases but would likely not respond to IL-5 inhibition.

Journal Editor

As a reviewer, what concerns would you raise regarding the choice of the primary endpoint in DREAM (clinically significant exacerbations) versus patient-reported outcomes like the Asthma Control Questionnaire (ACQ), given that the latter showed less consistent improvement?

Key Response

A reviewer would flag that while exacerbation reduction is a robust, objective clinical outcome of high interest to payers and clinicians, the lack of robust improvement in subjective symptoms (ACQ) might suggest that the drug's impact on a patient's daily quality of life is less transformative than its impact on hospitalizations. An editor would demand a clear discussion on whether the drug is 'disease-modifying' in terms of acute events or merely a 'supplemental' therapy for a subset of the disease's manifestations.

Guideline Committee

How did the DREAM trial contribute to the GINA (Global Initiative for Asthma) Step 5 recommendations, and what specific evidence level would you assign to its findings for the reduction of asthma exacerbations?

Key Response

The DREAM trial provided Level 1 evidence that anti-IL-5 therapy is effective for severe eosinophilic asthma. This led GINA and other guideline bodies to update Step 5 management to include phenotyping (checking blood eosinophils and FeNO) and recommending biologics like mepolizumab for those who remain uncontrolled despite optimized Step 4 therapy. It shifted the paradigm from escalating steroids (which have systemic side effects) to adding targeted biologics based on the underlying inflammatory endotype.

Clinical Landscape

Noteworthy Related Trials

2014

MENSA Trial

n = 576 · NEJM

Tested

Intravenous or subcutaneous mepolizumab

Population

Patients with severe eosinophilic asthma

Comparator

Placebo

Endpoint

Annualized rate of clinically significant asthma exacerbations

Key result: Mepolizumab significantly reduced the rate of clinically significant exacerbations compared to placebo.

2014

SIRIUS Trial

n = 135 · NEJM

Tested

Mepolizumab 100 mg subcutaneous every 4 weeks

Population

Patients with severe asthma requiring oral corticosteroids

Comparator

Placebo

Endpoint

Percentage reduction in daily oral glucocorticoid dose

Key result: Patients receiving mepolizumab achieved greater reductions in oral corticosteroid use while maintaining asthma control.

2017

CALIMA Trial

n = 1376 · Lancet

Tested

Benralizumab (30 mg) every 4 or 8 weeks

Population

Patients with severe, uncontrolled asthma with eosinophilic phenotype

Comparator

Placebo

Endpoint

Annual asthma exacerbation rate

Key result: Benralizumab significantly reduced annual exacerbation rates and improved lung function in patients with elevated blood eosinophils.

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