Mepolizumab as Possible Treatment for Allergic Bronchopulmonary Aspergillosis: A Review of Eight Cases

Allergic bronchopulmonary aspergillosis (ABPA) is an eosinophilic pulmonary disorder caused by a hypersensitivity reaction to Aspergillus fumigatus that manifests with uncontrolled asthma, peripheral blood eosinophilia, and radiological findings, such as mucus plugging. Early diagnosis and proper treatment of ABPA are essential to prevent irreversible lung damage such as pulmonary fibrosis and bronchiectasis and improve the quality of life of patients. Beside inhaled medication for asthma, anti-inflammatory agents (i.e., systemic glucocorticoids) and antifungal agents are the mainstay treatment of ABPA. The goal of therapy using glucocorticoids and antifungal agents is to suppress the immune hyperreactivity to A. fumigatus and attenuate the fungal burden. Since the systemic glucocorticoid therapy may lead to serious adverse effects including osteoporosis, avascular necrosis, myopathy, cushingoid appearance, hypertension, insomnia, and increased risk of infection, a glucocorticoid-sparing agent could be considered. Mepolizumab is a humanized monoclonal antibody that binds to interleukin-5, which is the key mediator for eosinophil differentiation, activation, migration, and survival. We review eight cases of ABPA treated successfully with mepolizumab. Treatment with mepolizumab was not restricted to the total immunoglobulin E level, the limiting factor for omalizumab in ABPA. In addition, mepolizumab therapy improved forced expiratory volume in one second, radiological findings, and patient quality of life.