Introduction:

Mepolizumab (Mepo), a monoclonal antibody (mAb) targeting IL-5, is an add-on treatment for severe eosinophilic asthma (SEA). Data on long-term, real-world outcomes are limited. We evaluated 5-year outcomes of Mepo among patients with SEA.

Methods:

Data were collected on patients with SEA starting Mepo in 2017 at our centre and measured over 5 years. Oral corticosteroid (OCS) use was recorded at baseline and 6 monthly intervals. Patient outcomes were collected, and ? where applicable ? timeline of treatment discontinuation reviewed.

Results:

37 patients started Mepo in 2017 (age 55±12.5, M=11, BMI 32±6); 17 remained on therapy at 5 years. Characteristics of those who continued v discontinued Mepo were not significantly different. At 5 years, those continuing Mepo maintained significant annual OCS course reduction (6.17 v. 0.06, p=<0.05); 12/13 patients on maintenance OCS at mAb commencement were completely weaned by 2 years.

20 patients discontinued treatment, with 7 early (<12m) and 13 late (>12m) failures. Three discontinued early due to side effects (1 skin eruption, 2 hypersensitivity reactions). The most common discontinuation reason was lack of efficacy (12/20, 32% of total patients). 10 subsequently trialled a second mAb (Benraluzimab n=8, Dupilumab n=2), with 5/8 who trialled Benralizumab discontinuing due to lack of clinical effect.

Conclusions:

Almost half of our cohort who commenced Mepo in 2017 have ongoing clinical benefit 5 years on. Late failure occurred more often than early failure, suggesting a potential waning of response, and highlighting the importance of continued close assessment of patients commenced on mAbs to ensure treatment choice is optimised.