Early Intervention with Mepolizumab, Corticosteroids, and Intravenous Immunoglobulin for Dupilumab-Triggered Eosinophilic Granulomatosis with Polyangiitis: A Case Report.

Introduction: Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare complication during dupilumab therapy. However, the optimal treatment strategy for dupilumab-triggered EGPA remains unclear, particularly the timing and role of anti-interleukin-5 therapy.

Case study: A 48-year-old female with severe eosinophilic rhinosinusitis and asthma, increased blood eosinophils (2098/μL) and myeloperoxidase-specific antineutrophil cytoplasmic antibody (MPO-ANCA) (46.1 U/mL) without vasculitic symptoms, developed systemic symptoms, including fever, arthralgia, and peripheral neuropathy immediately after dupilumab administration.

Results: Physical assessment revealed bilateral expiratory wheezes and laboratory tests revealed marked elevations in blood eosinophil (11,889/μL) and MPO-ANCA levels (125.0 U/mL). Other conditions, including parasitic infections, allergic bronchopulmonary aspergillosis, and FIP1L1-PDGFRA-positive disease, were excluded. Early intervention with mepolizumab (300 mg), methylprednisolone pulse therapy, and intravenous immunoglobulin (IVIG) was initiated after discontinuing dupilumab, resulting in rapid normalization of blood eosinophil counts and clinical improvement. Residual neuropathy was successfully treated with intravenous immunoglobulin (IVIg). Prednisolone was reduced to 15 mg daily with negative MPO-ANCA one month after treatment initiation.

Conclusion: This case emphasizes the importance of monitoring preexisting MPO-ANCA and blood eosinophils before and during dupilumab therapy. Early intervention with mepolizumab combined with conventional therapy is considered an optimal treatment strategy for dupilumab-triggered EGPA.