The FDA has approved benralizumab (Fasenra -AstraZeneca), a humanized monoclonal antibody selective for the interleukin-5 (IL-5) receptor, for add-on maintenance treatment of severe asthma in patients Ն12 years old with an eosinophilic phenotype. Benralizumab is the third anti-IL-5 antibody to be approved for treatment of severe eosinophilic asthma; mepolizumab (Nucala) and reslizumab (Cinqair), which target IL-5 itself, were approved earlier. 1,2
Mechanism of ActionSevere asthma often has an eosinophilic phenotype with elevated blood and lung eosinophil levels. 3,4 IL-5 is the major cytokine responsible for the growth, differentiation, recruitment, activation, and survival of eosinophils. Mepolizumab and reslizumab, the two previously approved anti-IL-5 antibodies, reduce the production and survival of eosinophils by binding to IL-5, preventing it from binding to its receptors (Table 1). Benralizumab binds directly to the IL-5 receptor, preventing IL-5 binding and causing apoptosis of eosinophils and basophils through cell-mediated cytotoxicity. All three of these agents decrease eosinophilic airway inflammation.