Effect of Mepolizumab in airway's remodelling in patients with late-onset severe asthma with an eosinophilic phenotype.

Background: Clinical 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.

Objective: We thus investigated the effect of mepolizumab on airway structural remodelling in patients treated for severe asthma in routine clinical care.

Methods: MESILICO 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.

Results: After 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).

Conclusion: This 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.