A rare case of sudden blindness following mepolizumab withdrawal in EGPA.

Background: Eosinophilic granulomatosis with polyangiitis (EGPA) is a small-vessel vasculitis primarily affecting individuals with asthma and hypereosinophilia. Among the available treatment options for EGPA, biological therapies such as Mepolizumab have emerged for controlling eosinophilic inflammation and reducing corticosteroid dependence. Mepolizumab is a humanized monoclonal antibody that inhibits the interleukin-5 binding to its alpha-subunit receptor, which is predominantly expressed in human eosinophils. While Mepolizumab effectively reduces exacerbations and corticosteroid use, a significant proportion of patients continue to experience disease activity and relapses. Moreover, the implications of treatment discontinuation remain poorly understood.

Case report: We present a clinical case of a 38 year-old patient diagnosed with anti-neutrophil cytoplasmic antibody (ANCA)-negative EGPA in 2015 based on clinical and laboratory criteria. The patient underwent a treatment regimen that included Methotrexate, Mepolizumab, and oral corticosteroids, achieving significant improvement in respiratory symptoms. However, approximately seven months after discontinuing a five-year treatment with Mepolizumab due to personal choice, the patient experienced sudden, progressively worsening and permanent blindness in the right eye.

Conclusions: The permanent blindness observed in our patient may be associated with Mepolizumab withdrawal. Currently, there is limited clinical evidence regarding the effects of biologic therapy discontinuation, even in patients with stable diseases. To our knowledge, this is the first reported case of EGPA-associated blindness following Mepolizumab withdrawal. Our case underscores the need for long-term monitoring and careful risk assessment before considering treatment discontinuation, even in the absence of active symptoms.