Inflammation Following Mepolizumab and Oral Corticosteroids in Asthma

Mepolizumab, a humanized monoclonal antibody (mAb) antagonizes IL-5 and through a selective inhibition of eosinophilic inflammation, reduces the number of eosinophils in sputum and blood, leading to a reduction in asthma exacerbations and a need for systemic glucocorticoids. Once this therapy has been initiated for severe eosinophilic asthma, the additional role of oral corticosteroids is questionable as their main target is reduction of eosinophils and hence responsiveness to oral corticosteroids in patients in a stable state of asthma may reduce. Using two weeks of high dose prednisolone versus placebo in a crossover design after 12 weeks of mepolizumab therapy will allow an understanding of the pathways that remain steroid responsive following IL-5 suppression. This is an exploratory study with no single primary end point. The objective of the study is to assess the change in airway inflammation following oral corticosteroids versus placebo and the airway inflammation while on mepolizumab in stable state of asthma. Note: Mepolizumab is not an intervention in this study; it is initiated as part of usual NHS care.