Anti-interleukin-5 therapy in severe asthma

Asthma is a chronic inflammatory disorder of the airways that leads to acute symptoms, exacerbations and sometimes, for a small part of the asthmatic population, fatal or near-fatal exacerbations. This as yet significant minority of individuals present with severe asthma and have persisting daily symptoms, and exacerbations despite compliance with high doses of inhaled steroids and additional treatment. For more than a decade, the pharmacological management of patients with severe asthma has focused on evaluating specific cytokines. The rationale of this approach is based on the distinguished key role played by eosinophils in the asthma inflammatory processes. Eosinophils are recruited from the circulation to airways where they cause airway damage via different mechanisms. Eosinophils are regulated in terms of their recruitment, activation, growth, differentiation and survival by interleukin (IL)-5. Abundant data from in vitro experiments, animal models and clinical trials has confirmed that IL-5 inhibition may be an effective approach for the treatment of asthma, especially severe asthma. Interfering with eosinophil function or reducing their numbers has been one of the most important goals of therapeutic monoclonal antibodies, which target cytokine receptor interactions in asthma, particularly IL-5. This review will consider new treatments options for severe asthma, particularly those targeting IL-5, that have already been evaluated in clinical trials in asthmatic patients.