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Prospective Open-Label Study of 48-Week Subcutaneous Administration of Mepolizumab in Japanese Patients with Severe Eosinophilic Asthma

Kurosawa M, Sutoh E
Department of Allergy and Respiratory Medicine, Sutoh Hospital, Annaka, Gunma, Japan

J Investig Allergol Clin Immunol 2019; Vol. 29(1)
doi: 10.18176/jiaci.0285

Background: Long-term efficacy and safety of mepolizumab in patients with severe eosinophilic asthma has been evaluated by large-scale double-blinded placebo control studies. However, a prospective open-label study of a long-term subcutaneous administration of mepolizumab in Japanese patients with severe eosinophilic asthma has not been reported.
Methods: This study was a prospective, 48-week, open-label trial in 32 Japanese patients with severe eosinophilic asthma who received subcutaneous administration of 100 mg mepolizumab every 4 weeks. Nine patients required daily use of oral corticosteroid despite the use of high-dose inhaled corticosteroid. Six patients with aspirin-exacerbated respiratory disease were involved.
Results: No patients failed to be continued mepolizumab administration for an entire trial period. All patients experienced no adverse events during the treatment. None of the patients experienced asthma exacerbations during an entire period. In fact, forced expiratory volume in one second was increased significantly at 24 week (p < 0.01) and at 48 week (p < 0.05). Number of eosinophils in peripheral blood was reduced after the first administration of mepolizumab in all patients, which was continued until 48 weeks with mepolizumab administration. After the start of mepolizumab administration, all of oral corticosteroid-dependent asthmatics successfully withdrew from the use of corticosteroid without exacerbations in parallel with sustained reduction in peripheral blood eosinophil count. Blood levels of thymus and activation-regulated chemokine and IgE were not changed with 48-week administration of mepolizumab.
Conclusion: This first prospective open-label pilot study in Japan showed a long-term efficacy and safety of mepolizumab in patients with severe eosinophilic asthma.

Key words: Anti-IL-5 antibody, Eosinophilic asthma, Mepolizumab, Prospective open-label study, Thymus and activation-regulated chemokine