Tolerance and rebound with zafirlukast in patients with persistent asthma

Leukotriene-receptor antagonists versus placebo in the treatment of asthma in adults and adolescents: a systematic review and meta-analysis

BACKGROUND

Leukotriene-receptor antagonists (LTRAs) are recommended as an alternative treatment in patients with mild asthma, but their effect compared with placebo is unclear.

PURPOSE

To determine the benefits and harms of LTRAs as monotherapy or in combination with inhaled corticosteroids compared with placebo in adults and adolescents with asthma.

DATA SOURCES

MEDLINE and the Cochrane Central Register of Controlled Trials from inception through June 2015.

STUDY SELECTION

Peer-reviewed, English-language, randomized, controlled trials in patients with asthma that reported the effect of LTRAs versus placebo on measures of asthma control.

DATA EXTRACTION

Three researchers extracted data on study population, interventions, outcome measures, and adverse events. One researcher assessed risk of bias.

DATA SYNTHESIS

Of the 2008 abstracts that were screened, 50 trials met eligibility criteria. Random-effects meta-analyses of 6 trials of LTRA monotherapy showed that LTRAs reduced the risk for an exacerbation (summary risk ratio [RR], 0.60 [95% CI, 0.44 to 0.81]). In 4 trials of LTRAs as add-on therapy to inhaled corticosteroids, the summary RR for exacerbation was 0.80 (CI, 0.60 to 1.07). Leukotriene-receptor antagonists either as monotherapy or as add-on therapy to inhaled corticosteroids increased FEV1, whereas FEV1 percentage of predicted values was improved only in trials of LTRA monotherapy. Adverse event rates were similar in the intervention and comparator groups.

LIMITATION

Variation in definitions and reporting of outcomes, high risk of bias in some studies, heterogeneity of findings, possible selective outcome reporting bias, and inability to assess the effect of asthma severity on summary estimates.

CONCLUSION

Leukotriene-receptor antagonists as monotherapy improved asthma control compared with placebo, but which patients are most likely to respond to treatment with LTRAs remains unclear.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Does zafirlukast reduce future risk of asthma exacerbations in adults? Systematic review and meta-analysis

Background and objective

The purpose of asthma management is to achieve a total asthma control that involves current control and future risk. It has proven efficacy in reducing asthma exacerbations, but the effect size of zafirlukast for asthma exacerbations of various severity is not systematically explored.

Methods

Randomized controlled trials were searched in PubMed Central, Web of Science, and Embase, where zafirlukast prevented asthma exacerbations in adults. The primary outcome was asthma exacerbations, the secondary outcomes were asthma exacerbations requiring systemic corticosteroids and emergency visits, respectively. Odds ratio (OR) with 95% confidence intervals (CI) were pooled.

Results

Twelve trials were identified. As first-line therapy, compared to those having placebo, the patients with chronic asthma receiving zafirlukast experienced statistically lower asthma exacerbations (OR = 0.68, 95% CI = [0.45, 1.00]), but it was not found that zafirlukast was superior to placebo in asthma exacerbations requiring systemic corticosteroids (OR = 0.76, 95% CI = [0.45, 1.29]). Furthermore, zafirlukast was inferior to ICs in asthma exacerbations (OR = 2.11, 95% CI = [1.35, 3.30]) and requiring systemic corticosteroids (OR = 3.71, 95% CI = [1.82, 7.59]). As add-on therapy, zafirlukast was not superior to placebo in asthma exacerbations (OR =0.99, 95% CI = [0.54, 1.81] and requiring emergency visits (OR = 0.72, 95% CI = [0.18, 2.99]). Intriguingly, there was not a significant difference in asthma exacerbations between zafirlukast and ICs (OR = 1.12, 95% CI = [0.53, 2.34]).

Conclusions

Our study suggests that zafirlukast, as the first-line therapy, significantly reduces mild to moderate but not severe asthma exacerbations. In the add-on regimen, zafirlukast could not reduce asthma exacerbations, which would perhaps result from small sample size and needs to be further studied.

Which biomarkers are effective for identifying Th2-driven inflammation in asthma?

Recognition of asthma as a heterogeneous disease revealed different potential molecular targets and urged the development of targeted, customized treatment modalities. Evidence was provided for different inflammatory subsets of asthma and more recently, further refined to T helper (Th)2-high and Th2-low subphenotypes with different responsiveness to standard and targeted pharmacotherapy. Given these differences in immunology and pathophysiology, proof of concept studies of novel treatment modalities for asthma should be performed in adequate, well-defined phenotypes. In this review, we describe both existing and novel biomarkers of Th2-inflammation in asthma that can be applied to classify asthma subphenotypes in clinical studies and for treatment monitoring.