Rapid effect of benralizumab in exacerbation of severe eosinophilic asthma associated with eosinophilic granulomatosis with polyangiitis

BACKGROUND: Eosinophilic granulomatosis with polyangiitis (EGPA) is a disease that is associated with severe uncontrolled eosinophilic asthma. Eosinophils play an important pathogenic role in the development of both diseases. Benralizumab is an antieosinophilic monoclonal antibody that binds to the α subunit of the human interleukin 5 receptor that is expressed on the surface of the eosinophil and basophil. We present the first case of rapid improvement in symptoms and lung function during admission for exacerbation of a severe eosinophilic asthma associated with EGPA. CASE PRESENTATION: A 57-year-old man diagnosed with severe eosinophilic asthma associated to EGPA was admitted to the Pulmonology Department due to severe bronchospasm. At admission he presented 2300 eosinophils/µl. Despite intensive bronchodilator treatment, intravenous methylprednisolone at a dose of 80 mg/d, oxygen therapy, and budesonide nebulization, the patient continued to present daily episodes of bronchospasm. Ten days after admission, with blood eosinophil levels of 1700 cells/µl, benralizumab 30 mg sc was administered. That day, the Forced Expiratory Volume in the first second (FEV1) was 28% of the theoretical value (1150 ml). AT three days, FEV1 increased to 110 ml (31%). On the 9th day FEV1 was 51% (2100 ml). The blood eosinophil level on the 9th day was 0 cells/µl. CONCLUSIONS: The rapid improvement of FEV1 is in line with studies based on clinical trials that found improvement after two days in peak flow and one phase II study that showed rapid response in exacerbation of asthma in the emergency room. The antieosinophilic effect at 24 h and the effect in different tissues determine the rapid improvement and the potential advantage of benralizumab in the treatment of EGPA. This case suggests the usefulness of benralizumab in patients with EGPA and eosinophilic severe asthma who show bronchospasm refractory to conventional treatment during a hospitalization due to asthma exacerbation.