Outcomes after cessation of mepolizumab therapy in severe eosinophilic asthma: A 12-month follow-up analysis

A theoretical risk of "rebound" worsening of eosinophilic airway inflammation associated with negative outcomes has been suggested3 on the basis of in vitro observations that anti-IL-5 therapy is associated with upregulation of IL-5 synthesis by TH2 cells, upregulation of IL-5R expression by eosinophils, and persistence of preformed IL-5 in complex with the drug for a variable period of time after cessation of therapy.4 As part of a follow-up analysis, subjects completing a 12-month study of mepolizumab in refractory asthma1 were observed for 12 months with assessments every 3 months. The rise in exacerbations at 3 to 6 months after stopping mepolizumab was preceded by a rise in sputum and blood eosinophils, supporting suggestions that these events are related but have different time courses.5-8 The finding of increased asthma symptoms following cessation of mepolizumab was unexpected because symptoms were not modified significantly during the treatment period.1 However, mean symptom scores for subjects receiving mepolizumab were lower than for subjects in the placebo group at the end of the treatment phase of the study.