Anti−Eosinophil Therapy for Chronic Obstructive Pulmonary Disease: Mixed Results

Mepolizumab (Nucala), is an anti–interleukin-5 monoclonal antibody that inhibits eosinophils and lowers asthma exacerbation rates (NEJM JW Gen Med Oct 1 2014 and N Engl J Med 2014; 371:1198), but its role in chronic obstructive pulmonary disease (COPD) is unknown.

In two industry-funded phase III trials, 1510 COPD patients with histories of moderate-to-severe exacerbations despite triple therapy with inhaled corticosteroids, long-acting muscarinic agents, and long-acting β-agonists were randomized to add-on therapy with subcutaneous mepolizumab or placebo for 1 year. In one trial, in which patients were stratified based on eosinophil counts, those with eosinophilic phenotypes (peripheral eosinophil count ≥150 mm³ at enrollment or ≥300 mm³ du…