BackgroundClinical trials and real-world experience have provided evidence for the clinical benefit of mepolizumab, an anti-IL-5 biologic, in severe asthma. However, limited data exists regarding the impact of mepolizumab on airway remodelling. ObjectiveWe thus investigated the effect of mepolizumab on airway structural remodelling in patients treated for severe asthma in routine clinical care. MethodsMESILICO is a multicenter study involving 8 Pulmonology Departments in Greece. This study focused on patients who initiated mepolizumab for severe asthma with an eosinophilic phenotype and had late-onset disease with obstructive patterns (impaired reversibility). Forty-seven patients were recruited, of whom 41 were enrolled in the bronchoscopy sub-study. The findings were related to clinical outcome. ResultsAfter 12 months, mepolizumab treatment was associated with significant improvements in lung function and ACT score, along with a significant decrease in severe exacerbation events (p<0.001). Thirty four of the 41 participants (83%) had paired biopsies for comparative analysis. There was a significant reduction from baseline in sub-basement membrane thickness, airway smooth muscle area, airway smooth muscle layer thickness and extent of epithelial damage, as well as a decrease in tissue eosinophil numbers (all p<0.001). The extent of ASMLT reduction positively correlated with the submucosal eosinophil reduction (r= 0.599, p<0.001). ConclusionThis study identifies that 12 month of mepolizumab treatment in patients with late-onset severe asthma, who are also characterized by eosinophilic and impaired reversibility phenotypes, leads not only to clinical improvement but also reduces indices of airway tissue remodelling suggestive of a disease modifying effect.
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