Friend or Foe? Eosinophilic Granulomatosis with Polyangiitis (EGPA) Onset After Dupilumab: Report of Two Cases and a Narrative Review of the Literature

Background/Objectives: Dupilumab is a fully human IgG4 monoclonal antibody targeting the interleukin-4 receptor α subunit, inhibiting interleukin-4 and interleukin-13 signalling, and suppressing type 2 inflammation. It is approved for several eosinophilic and type 2 inflammatory diseases, including chronic rhinosinusitis with nasal polyps, asthma, atopic dermatitis, eosinophilic oesophagitis, and, more recently, eosinophilic chronic obstructive pulmonary disease. Although generally well tolerated, dupilumab has been associated with peripheral eosinophilia and, rarely, eosinophil-mediated complications. This study aims to describe cases of eosinophilic granulomatosis with polyangiitis (EGPA) occurring after dupilumab initiation and to review available evidence on this association. Methods: We describe two cases of new-onset EGPA developing after the introduction of dupilumab therapy, analysing clinical features, laboratory findings, management, and outcomes. A narrative review of published case reports and literature addressing dupilumab-associated eosinophilia and EGPA was also performed. Results: Both patients developed EGPA after starting dupilumab, presenting with marked peripheral eosinophilia and systemic manifestations consistent with the disease. Clinical improvement was observed following dupilumab discontinuation and initiation of appropriate immunosuppressive treatment. The literature review identified a small number of similar reports describing EGPA onset or unmasking in temporal association with dupilumab, mainly in patients with underlying type 2 inflammatory disorders. Conclusions: While a causal relationship between dupilumab and EGPA remains unproven, these findings highlight the importance of clinical awareness. Dupilumab remains an effective therapy for severe type 2 inflammatory diseases; careful monitoring may allow early recognition and management of rare eosinophilic complications.