Effect of Benralizumab on Mucus Plugs in Severe Eosinophilic Asthma

Introduction: Mucus plugs are associated with airway obstruction in severe asthma and are involved in the formation of activated eosinophils. Benralizumab, an anti-interleukin-5 receptor antibody, markedly reduces not only peripheral blood eosinophils but also airway eosinophils; however, its effects on mucus plugs have not been clarified. In this study, we examined the efficacy of benralizumab on mucus plugs using computed tomography (CT) imaging. Methods: Twelve patients who were administered benralizumab and underwent CT before and approximately 4 months after the introduction of benralizumab were included in this study, and the number of mucus plugs before and after benralizumab administration was compared. The correlation between the clinical background and treatment effect was also examined. Results: The number of mucus plugs significantly decreased after the introduction of benralizumab. The number of mucus plugs was correlated with sputum eosinophil percentage and eosinophil cationic protein in the sputum supernatants and inversely correlated with forced expiratory volume in 1 s (FEV1). Benralizumab induction resulted in a marked decrease in blood and sputum eosinophil levels and a significant improvement in asthma symptoms, quality of life scores, FEV1, and exacerbation frequency. Furthermore, there was a significant correlation between the reduction in mucus plugs and changes in the symptom score or FEV1. Discussion/Conclusion: These data suggest that benralizumab may have the potential to improve symptoms and respiratory function in patients with severe eosinophilic asthma by reducing mucus plugs.