Asthma Exacerbation Profile on open label treatment with Benralizumab for severe eosinophilic asthma [BenRex]

<bold>Background:</bold> Asthma exacerbations cause major morbidity and their treatment with oral corticosteroids [OCS] can lead to toxicity. In clinical trials, benralizumab, an Interleukin-5 receptor-α blocker, reduced exacerbations by approximately 50%. <bold>Research</bold> showed that exacerbations on mepolizumab are either eosinophilic or infective. Aim of BenRex was to study inflammatory and physiological features of exacerbations while on benralizumab. <bold>Methods:</bold> 15 UK centres participated. Benralizumab was initiated as per NICE/SMC guidance. Subjects were asked to contact the site if they exacerbated and before starting OCS/antibiotics, to have clinical review, spirometry, fractional exhaled nitric oxide (FeNO) and give samples of sputum, urine, nasosorption, gargle and blood. <bold>Results:</bold> Of 157 subjects enrolled, 91 (58%) exacerbated during the 12-18 month follow up. Of 272 exacerbations, 120 visits were on-site before treatment. See participant characteristics with and without an exacerbation in the Table. At exacerbation, median [IQR] for blood eosinophils x109/L was 0 [0,0], sputum eosinophils% was 0 [0,0] and FeNO ppb was 49 [29,92]. Median [IQR] sputum neutrophil% was 66.63[34.00, 84.00] and mean (SD) CRP mg/L was 14.6 (23). <bold>Conclusion:</bold> During exacerbations on benralizumab, eosinophils remain suppressed in the blood and airways, FeNO remains elevated and infective features such as sputum neutrophilia and rise in CRP occur. <fig><object-id>erj;64/suppl_68/PA5356/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>