Mepolizumab (Bosatria(®), GlaxoSmithKline) is a biologic agent developed to 
treat asthma. It represents a humanized monoclonal antibody of IgG1 κ type, 
which targets human IL-5 and thus prevents its interaction with the α-chain of 
the IL-5 receptor. To date, it has not been approved for use in any 
eosinophil-related disorder; however, several studies have suggested some 
therapeutic benefit across a spectrum of eosinophil-related disorders. This 
article evaluates the currently available preclinical and clinical studies, and 
the impact of mepolizumab against a variety of eosinophilic disorders.