Long-Term Safety and Efficacy of Mepolizumab in Patients with Severe Eosinophilic Asthma
Saturday, March 5, 2016
South Exhibit Hall H (Convention Center)
Frank C. Albers, M.D., Ph.D., Njira Lugogo, Martyn J Gilson, Robert Price, Steven W Yancey
Rationale: To describe the safety profile of long-term mepolizumab treatment and its effects on markers of asthma control in patients with severe eosinophilic asthma.    

Methods: Following completion of MEA115588 and MEA115575 (both double-blind studies), 651 patients with severe eosinophilic asthma entered a 52-week open-label extension study (MEA115661), receiving mepolizumab 100mg subcutaneous every 4 weeks adjunctive to standard care.

Results: On-treatment adverse events (AEs) and serious AEs were reported in 558(86%) and 94(14%) patients, respectively. Asthma exacerbation 38(6%) was the most common serious AE. No fatal AEs were reported. Systemic and local site reactions were reported in 13(2%) and 29(4%) patients, respectively, with no reports of mepolizumab-related anaphylaxis. Rates of AEs during MEA115661 were similar to placebo during the double-blind studies. For patients commencing mepolizumab in MEA115661, ACQ-5 scores were improved at Week 4 (mean change from baseline: -0.28) and maintained through Week 52. For patients continuing mepolizumab, ACQ-5 scores were maintained. In a post-hoc analysis combining MEA115588 and MEA115661, exacerbation rate/year remained low in patients continuing mepolizumab (Weeks 0–32 [double-blind]: 0.91; Weeks 32–52: 0.92; Weeks 52–84: 0.92). For patients previously treated with placebo, exacerbation rates decreased over time, from 1.94/year to 1.04/year when switched to mepolizumab.

Conclusions: The safety profile of mepolizumab over 52 weeks open-label treatment was similar to previous studies. Improvements in markers of asthma control during MEA115588/MEA115575 were maintained during MEA115661, supporting long-term treatment in patients with severe eosinophilic asthma. Patients initiating mepolizumab in MEA115661 demonstrated similar improvements to those in MEA115588/MEA115575. Funding: GSK (NCT01842607).