Case study: mepolizumab prevents progression of eosinophilic granulomatosis with polyangiitis with involvement of the central nervous system which is refractory to conventional immunotherapy

Abstract

Abstract Eosinophilic granulomatosis with polyangiitis (EGPA) is a systemic vasculitis involving small-sized vessel. It manifests mainly as asthma or eosinophilia, but the literature reported involvement of the central nervous system (CNS) in 5%, while isolated CNS involvement is very rare. We describe a case of isolated CNS involvement of EGPA which was refractory to conventional immunotherapy and treated with mepolizumab, an anti-interluekin-5 monoclonal antibody. A previously healthy 51-year-old man was referred to the neurology department for memory decline persisting for a month. Magnetic resonance imaging (MRI) showed the multifocal lesion in the periventricular and frontal lobe. Analysis of cerebrospinal fluid revealed an elevated protein concentration and leukocytosis. Considering his age, clinical course, and laboratory findings, steroid and intravenous immunoglobulin was started for autoimmune encephalopathy. Two months after discharge, the patient experienced new symptom – gait disturbance. The follow-up MRI showed increased extent of the previous lesions and the new lesions. To confirm the diagnosis, brain biopsy was done, and the finding was consistent with EGPA. We decided to start mepolizumab as second-line treatment, and observe the stationary course and absence of further progression of the lesion in the follow-up MRI. Mepolizumab for EGPA patients was introduced to achieve protocol-defined remission and clinical benefit compared to the placebo group in the several studies. Our case signifies possibility of mepolizumab to halt further progression of the disease clinically and radiologically, for the patient with isolated CNS involvement of EGPA which is unresponsiveness to conventional immunotherapy.