Real world outcomes of Mepolizumab for severe asthma in Wales a retrospective analysis

Introduction: Mepolizumab, a monoclonal antibody targeting IL-5, was approved by NICE for use in the UK in 2017. Clinical trials demonstrated a clinically significant reduction in both steroid dose and exacerbation frequency; with published real world accounts of this drug in the UK echoing these results. (Kavanagh, et al., Thorax 2018; pp.73:A174-A175) (Gittins, et al., Thorax 2018pp.73:A51-A52). The aim of the study is to assess the efficacy of this drug on our patient cohort. Method: A retrospective review of patient outcomes across 4 health boards in Wales in patients who met NICE criteria for therapy and had completed over 52 weeks of treatment of Mepolizumab. Oral corticosteroid dose and exacerbation frequency were recorded at the start of treatment and at 52 weeks. Results: Eighty-one patients were included in the analysis (Female 59%). Sixty-nine (84%) were deemed responsive to Mepolizumab. In patients beginning the trial on oral corticosteroids (n=55) we observed an overall response rate of 82%. This included 32 (58%) patients with a greater than 50% reduction in their OCS and 10 (18%) stopping OCS completely by the end of one year. In patients with frequent exacerbations but not on oral corticosteroids (n=26) we observed an overall response rate of 88%. The number of patients experiencing a reduction in exacerbation frequency of over 50% was 21 (81%). Conclusions: Mepolizumab was associated with a significant reduction in both oral corticosteroid dose (mean reduction 56%) and exacerbation frequency (mean reduction 74%) in patients deemed responsive to the drug. These response rates are comparable to outcomes at other UK centres.