Effect of mepolizumab in airway remodeling in patients with late-onset severe asthma with an eosinophilic phenotype

Background: Clinical trials and real-world experience have provided evidence for the clinical benefits of mepolizumab, an anti-IL-5 biologic, in severe asthma. However, limited data exist regarding the impact of mepolizumab on airway remodeling.

Objective: We sought to investigate the effect of mepolizumab on airway structural remodeling in patients treated for severe asthma in routine clinical care.

Methods: The MESILICO (Efficacy of Mepolizumab in patients with latE-onset Severe eosInophiLic asthma and fIxed obstruCtiOn) study 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 substudy. The findings were related to clinical outcome.

Results: After 12 months, mepolizumab treatment was associated with significant improvements in lung function and Asthma Control Test score, along with a significant decrease in severe exacerbation events (P < .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, extent of epithelial damage, and number of tissue eosinophils (all P < .001). The extent of reduction in airway smooth muscle layer thickness positively correlated with the submucosal eosinophil reduction (r = 0.599; P < .001).

Conclusions: This study identified that 12 months of mepolizumab treatment in patients with late-onset severe asthma, who are also characterized by eosinophilic and impaired reversibility phenotypes, not only leads to clinical improvement but also reduces indices of airway tissue remodeling suggestive of a disease-modifying effect.