Late Breaking Abstract - Benralizumab treatment strongly reduces blood basophils in patients with severe eosinophilic asthma

Abstract

Background: Benralizumab is a humanised anti-interleukin-5 receptor α monoclonal antibody that results in a depletion of blood eosinophils in patients with severe asthma. The impact of Benralizumab treatment on basophils is incompletely understood. Methods: In this study (ClinicalTrials.gov Identifier: NCT03652376), patients with severe eosinophilic asthma were treated with 3 doses of 30 mg Benralizumab subcutaneously: at study inclusion (baseline), and 1 month and 2 months after study inclusion. The Asthma Control Test (ACT) score, pulmonary function and blood cells were analysed at baseline, and 3 months (time point 2) and 5 months (time point 3) after study inclusion. Blood basophils were quantified by 2 different methods: flow cytometry using a fluorescence dye staining nucleic acid (Sysmex XE5000)(Method 1) and four-colour flow cytometry which identifies basophils as lineage negative, HLA-DR negative and CD123 positive cells (Method 2). Results: Twenty patients with severe eosinophilic asthma (median age: 56.5 years; 11 men, 9 women) were included in the study. Benralizumab treatment led to a depletion of blood eosinophils (0 cells / µl) and a significant increase in asthma control (median ACT score from 11 to 21 points) at time point 2. Blood basophils (median values, minimum-maximum) decreased from 40 cells / µl (20-100) at baseline to 10 cells / µl (0-30) at time point 2 (Method 1) and from 53 cells / µl (13-98) at baseline to 6 cells / µl (0-18) at time point 2 (Method 2). Conclusion: Benralizumab treatment strongly reduces basophils in patients with severe asthma, suggesting that the effects of Benralizumab in severe asthma might not be restricted to the depletion of eosinophils. Funding: This investigator-initiated study was funded by AstraZeneca (ESR-16-124 73).