Anti-IgE for chronic asthma in adults and children.

BACKGROUND

Omalizumab is a recombinant humanised monoclonal antibody directed against immunoglobulin E (IgE) to inhibit the immune system's response to allergen exposure. Omalizumab is directed against the binding site of IgE for its high affinity Fc receptor. It prevents free serum IgE from attaching to mast cells and other effector cells and prevents IgE mediated inflammatory changes.

OBJECTIVES

To determine the efficacy of anti-IgE in patients with allergic asthma

SEARCH STRATEGY

We searched the Cochrane Airways Group Asthma trials register (February 2003) for potentially relevant studies.

SELECTION CRITERIA

Randomised controlled trials examining anti-IgE administered in any manner for any duration.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed study quality and extracted and entered data. Three modes of administration were identified from the published literature (inhaled, intravenous and subcutaneous injection). Subgroup analysis was performed by asthma severity. Data were extracted from published and unpublished sources.

MAIN RESULTS

Eight trials were included in the review, contributing a total of 2037 mild to severe allergic asthmatic participants with high levels of IgE. Treatment with intravenous and subcutaneous Omalizumab significantly reduced free IgE compared with placebo. Omalizumab led to a significant reduction in inhaled steroid consumption compared with placebo: -114 mcg/day (95% CI -150 to -78.13, two trials). There were significant increases in the number of participants who were able to reduce steroids by over 50%: odds ratio (OR) 2.50, 95% confidence interval (CI) 2.02 to 3.10 (four trials); or completely withdraw their daily steroid intake: OR 2.50, 95%CI 2.00 to 3.13 (four trials). Participants treated with Omalizumab were less likely to suffer an asthma exacerbation with treatment as an adjunct to steroids (OR 0.49, 95%CI 0.38 to 0.64, four trials), or as a steroid tapering agent (OR 0.47, 95% CI 0.37 to 0.60, four trials).

REVIEWERS' CONCLUSIONS: Omalizumab was significantly more effective than placebo at increasing the numbers of patients who were able to reduce or withdraw their inhaled steroids, but the mean difference in steroid consumption achieved with Omalizumab was of debatable clinical value. The impressive effects observed in control groups bring into question the true effect of Omalizumab. Omalizumab was effective in reducing asthma exacerbations as an adjunctive therapy to inhaled steroids. Omalizumab was well tolerated, although the safety profile requires longer term assessment. Patient and physician assessment of the drug was positive. Further assessment in paediatric and severe adult populations is necessary, as is double-dummy comparison with inhaled corticosteroids.