Characterisation of severe eosinophilic asthma patients who failed Mepolizumab therapy

Background: In the UK, the criteria to withdraw mepolizumab therapy from patients with severe eosinophilic asthma include failure to achieve 50% reduction in exacerbation rate or a clinically important reduction in maintenance oral corticosteroids. Aim: To characterise the patients who failed to continue receiving mepolizumab Methods: Retrospective review of a clinical database and case notes for patients who received mepolizumab in Glenfield hospital, Leicester UK, between May 2017 to Feb 2020. Results: 21 out of a total 94 patients with severe eosinophilic asthma who received mepolizumab during the study period, had treatment stopped, the causes are listed in table 1. From the group considered to have failed mepolizumab therapy, 4/15 patients had underlying immunodeficiencies including common variable immune deficiency and specific antibody deficiency that required regular immunoglobulin therapy, 2/15 with bronchiectasis and recurrent bronchitis initiating prophylaxis Azithromycin therapy and 3/15 patients who requested treatment withdrawal due to lack of perceived benefits. The remaining 6/15 patients were deemed by the MDT to have failed mepolizumab therapy without a defined cause. Conclusion: Treatment failure with mepolizumab may be secondary to exacerbation events that are driven by infection, necessitating the need to characterise exacerbations carefully prior to initiating type-2 monoclonals in severe asthma.