Relationship between baseline fraction of exhaled nitric oxide (FeNO) and response to anti-IL-5/5R therapies in severe eosinophilic asthma (SEA)

Abstract

Introduction: Multiple biologic therapies targeting IgE, IL-4R, IL-5 and IL-5R are licensed for severe asthma. In all cases elevated blood eosinophil count is associated with improved clinical response. An elevated FeNO has also been shown to be a biomarker of response to dupilumab. As FeNO was not measured in the phase 3 program of mepolizumab or benralizumab it is unknown whether the same relationship exists for these therapies. Methods: A retrospective review of patients who completed 1 year of benralizumab or mepolizumab treatment at a large regional severe asthma centre was performed. Clinical characteristics (table 1) were recorded at baseline and each dosing visit. Patients were divided into 3 groups according to baseline FeNO and clinical outcomes compared (table 2). Results: 163 patients were identified. With the exception of FeNO, there were no differences in baseline characteristics between groups. At 1 year similar improvements in exacerbation rate, OCS use, ACQ and AQLQ was seen across groups. At 1 year FeNO fell from baseline in the FeNO high group by 22ppb without any change in the other groups (P Conclusion: In a large real-world SEA cohort, clinical effectiveness of mepolizumab and benralizumab is similar irrespective of baseline FeNO. This highlights limited applicability of elevated FeNO to assist in choosing between IL-4R and IL-5/5R classes.