D1.113 - Effect of mepolizumab in eosinophilic granulomatosis with polyangiitis (EGPA): a real-world retrospective observational study

Eosinophilic granulomatosis with polyangiitis (EGPA) is a systemic small- to medium-vessel vasculitis characterized by eosinophilic inflammation, asthma, and multi-organ involvement. Standard treatment is based on glucocorticoids and immunosuppressive agents in both maintenance and relapse phases. Mepolizumab, an anti–interleukin-5 monoclonal antibody, has been approved as add-on therapy in relapsing–remitting or refractory forms, demonstrating increased remission rates, reduced relapses, and a decreased dose of oral corticosteroids (OCS). However, real-life experience is limited. The aim of this study was to evaluate the clinical, analytical, and functional evolution of patients with EGPA treated with mepolizumab in a real-life context.

A retrospective observational study was conducted in adults with a clinical diagnosis of EGPA who met the 2022 EULAR/ACR classification criteria and were treated with mepolizumab 300 mg every 4 weeks for at least 12 months in a specialized asthma unit. Clinical variables, inflammatory biomarkers, and pulmonary function parameters were collected. Normality was assessed using the Shapiro–Wilk test. Paired comparisons between baseline and 12-month values were performed using the paired t-test or Wilcoxon signed-rank test. Results were expressed using descriptive statistics and p-values. The study was conducted in accordance with local ethical standards.

Twenty-three patients were included, with a mean age of 56.3 ± 16.3 years; 65.2% were women. A high burden of respiratory and inflammatory comorbidity was observed, with allergic rhinitis and nasal polyposis in 78.3%, atopy in 60.9%, and bronchiectasis in 56.5%. All patients were receiving OCS and inhaled therapy, 13% had received prior biologic treatment and 52.2% received immunosuppressive treatment during follow-up; at analysis, 6 patients had discontinued immunosuppression.

A significant reduction was observed in absolute blood eosinophil count (p < 0.001), eosinophil percentage (p < 0.0001), total immunoglobulin E (IgE) (p = 0.0098), number of exacerbations (p = 0.0137), and maintenance OCS dose (p = 0.0001), together with a significant increase in FEV₁ (% predicted) (p = 0.0393). Decreases in eosinophil cationic protein and fractional exhaled nitric oxide, as well as improved asthma control assessed by the Asthma Control Test, were observed without reaching statistical significance.

In this real-life clinical practice cohort, mepolizumab as add-on therapy in severe EGPA was associated with a significant reduction in eosinophilia, total IgE, exacerbations, and corticosteroid dependence, as well as an improvement in lung function after 12 months of treatment. Prospective studies are required to confirm these findings.