Mepolizumab and exacerbation frequency in refractory eosinophilic asthma: a randomised, double blind, placebo controlled trial

Mepolizumab which is a monoclonal antibody against interleukin 5, will effectively suppress eosinophilic airway inflammation and lower exacerbation frequency in severe asthmatics with evidence of persistent eosinophilic airway inflammation and a history of recurrent asthma exacerbations (greater than or equal to 2/year).. The hypothesis is based upon previous studies that have demonstrated a temporal relationship between a rise in sputum eosinophilia predicting onset of exacerbations. Steroid therapy targeted at lowering sputum eosinophil counts have been effective in lowering exacerbation frequency. Following on from this, mepolizumab has been shown in pilot studies to be effective in lowering both blood and sputum eosinophil counts and if the previous observations are robust in their hypothesis that sputum eosinophilia is causally related to asthma exacerbations, then we would expect mepoloizumab to achieve control of exacerbations through its mechanism of action. The present study has been designed to test this hypothesis.