Rapid effect of benralizumab in fulminant eosinophilic myocarditis in the setting of uncontrolled eosinophilic asthma

A 51-year-old male with uncontrolled asthma and recent convalescence from severe acute respiratory syndrome coronavirus-2c pneumonia presented with cough, dyspnea, and chest pain. Evaluation revealed significant peripheral eosinophilia, elevated troponin, and biventricular failure resulting in cardiogenic shock. He was diagnosed with eosinophilic myocarditis and was subsequently started on high-dose steroids. As he was also diagnosed with eosinophilic asthma and continued to clinically decline requiring inotropic support, he received benralizumab, an anti-eosinophilic monoclonal antibody, as rescue therapy. After benralizumab administration he demonstrated improvement in his left ventricular ejection fraction, normalization of his right ventricular function, and improvement in symptoms with resolution of his hypereosinophilia. Currently, benralizumab is approved for add-on maintenance treatment of patients with an eosinophilic phenotype of severe asthma. To date, only few observational studies have been published revealing rapid improvement in symptoms of acute, severe eosinophilic asthma and eosinophilic myocarditis caused by eosinophilic granulomatosis with polyangiitis after administration of benralizumab. This clinical case demonstrates that benralizumab can be used safely in conjunction with steroid therapy for eosinophilic myocarditis. This case also emphasizes the need for further clinical research for utilizing benralizumab in the treatment of eosinophilic myocarditis, eosinophilic asthma, and other hypereosinophilic syndromes in the acute setting. LEARNING OBJECTIVE: Benralizumab has been approved for add-on maintenance treatment of patients with an eosinophilic phenotype of severe asthma. However, few cases have been published demonstrating the drug's use in acute severe exacerbations. This case presents a patient with fulminant eosinophilic myocarditis and asthma with improvement after administration of benralizumab in addition to high-dose steroids. The future role of the drug in acute eosinophilic exacerbation should continue to be explored.