[Benralizumab in cases of eosinophilic granulomatosis with polyangiitis]

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare necrotizing vasculitis affecting small vessels and associated with severe asthma and eosinophilia. Monoclonal antibodies blocking the IL-5 signaling pathway, one example being benralizumab, decrease the proliferation of eosinophils and represent an effective treatment in severe eosinophilic asthma. They are a therapeutic option currently studied for EGPA. We report the paradoxical clinical case of EGPA appearing following the initiation of treatment with benralizumab (anti-IL-5R monoclonal antibody).

We describe the case of a 66-year-old female patient with severe asthma. Following the initiation of benralizumab, she showed deterioration of her general condition, associated with severe peripheral neuropathy of the lower limbs. At the same time, she developed massive hypereosinophilia. After an extensive workup, the patient was eventually diagnosed with an EGPA with multisystem involvement. Benralizumab was stopped and a course of high dose corticosteroids and immunosuppressants was initiated, enabling slow clinical recovery.

Anti-IL5 monoclonal antibodies, including benralizumab, are being investigated for new therapeutic indications, including EGPA. Paradoxically, a few rare cases of EGPA associated with these molecules have been reported in the literature. The causal link of this association remains hypothetical. Close monitoring of patients on benralizumab consequently seems indispensable.