Current and emerging biologic therapies targeting eosinophilic disorders

Eosinophilic disorders include a wide array of conditions in which eosinophils play a primary pathophysiologic role. While historically treated with corticosteroids and immunosuppressants, knowledge of eosinophil biology has led to the development of several biologics targeting eosinophils. In this review, we discuss the current US Food and Drug Administration (FDA) approved eosinophil-specific biologics targeting IL-5 (mepolizumab and reslizumab) and IL-5R (benralizumab) along with biologics under investigation targeting siglec-8 (lirentelimab). We discuss efficacy and safety data from trials of these medications in conditions including eosinophilic asthma, hypereosinophilic syndrome (HES), eosinophilic granulomatosis with polyangiitis (EGPA), chronic rhinosinusitis with nasal polyposis (CRSwNP), eosinophilic esophagitis (EoE), and eosinophilic gastrointestinal disease (EGID). Additionally, we discuss case reports utilizing these medications in conditions including drug reaction with eosinophilia and systemic symptoms (DRESS), allergic bronchopulmonary aspergillosis (ABPA), and eosinophilic pneumonia, among others. While eosinophilic targeting biologic therapy has been successful in eosinophilic asthma, HES, EGPA, and CRSwNP leading to FDA approval for these conditions, trials treating EoE and EGID have been disappointing to date. Given the increasing number of trials utilizing these biologics, it will be imperative for the allergist-immunologist to stay up to date on the latest treatment options to provide the most optimal care for eosinophilic disorders.