Anti‐IL5 therapies for asthma

Background This review is the first update of a previously published review in The Cochrane Library (Issue 7, 2015). Interleukin‐5 (IL‐5) is the main cytokine involved in the activation of eosinophils, which cause airway inflammation and are a classic feature of asthma. Monoclonal antibodies targeting IL‐5 or its receptor (IL‐5R) have been developed, with recent studies suggesting that they reduce asthma exacerbations, improve health‐related quality of life (HRQoL) and lung function. These are being incorporated into asthma guidelines. Objectives To compare the effects of therapies targeting IL‐5 signalling (anti‐IL‐5 or anti‐IL‐5Rα) with placebo on exacerbations, health‐related qualify of life (HRQoL) measures, and lung function in adults and children with chronic asthma, and specifically in those with eosinophilic asthma refractory to existing treatments. Search methods We searched the Cochrane Airways Trials Register, clinical trials registries, manufacturers' websites, and reference lists of included studies. The most recent search was March 2017. Selection criteria We included randomised controlled trials comparing mepolizumab, reslizumab and benralizumab versus placebo in adults and children with asthma. Data collection and analysis Two authors independently extracted data and analysed outcomes using a random‐effects model. We used standard methods expected by Cochrane. Main results Thirteen studies on 6000 participants met the inclusion criteria. Four used mepolizumab, four used reslizumab, and five used benralizumab. One study in benralizumab was terminated early due to sponsor decision and contributed no data. The studies were predominantly on people with severe eosinophilic asthma, which was similarly but variably defined. Eight included children over 12 years but these results were not reported separately. We deemed the risk of bias to be low, with all studies contributing data being of robust methodology. We considered the quality of the evidence for all comparisons to be high overall using the GRADE scheme, with the exception of intravenous mepolizumab because this is not currently a licensed delivery route. All of the anti‐IL‐5 treatments assessed reduced rates of 'clinically significant' asthma exacerbation (defined by treatment with systemic corticosteroids for three days or more) by approximately half in participants with severe eosinophilic asthma on standard of care (at least medium‐dose inhaled corticosteroids (ICS)) with poorly control