In Severe Eosinophilic Asthma, Anti–Eosinophil Therapy Prevents Exacerbations

As many as half of patients with severe asthma have persistent eosinophilia and frequent exacerbations, despite high-dose inhaled corticosteroid (ICS) or oral steroid therapy. Mepolizumab is a monoclonal antibody (not currently FDA-approved) that inactivates interleukin-5, the major cytokine involved in eosinophilic inflammation.

In an industry-sponsored international trial, 616 patients (mostly adults) were given monthly intravenous mepolizumab or placebo for 1 year. All patients had severe eosinophilic asthma (defined by ≥2 exacerbations in the past year), were receiving high-dose ICS or oral steroids, and exhibited one of the following: sputum eosinophilia of 3%, peripheral eosinophil count of 0.3×10⁹/L, markedly elevated exhaled nitric o…