In placebo-controlled trials, reslizumab, an anti-IL-5 monoclonal antibody, significantly reduced asthma exacerbations and improved lung function and asthma control in patients with eosinophilic asthma.

This open-label extension study evaluated safety and efficacy of reslizumab for up to 24 months.

After participation in 1 of 3 placebo-controlled, phase III trials in moderate-to-severe eosinophilic asthma, patients received reslizumab 3.0 mg/kg intravenously every 4 weeks for up to 24 months. Adverse events (AEs), lung function, and patient-reported asthma control were evaluated.

In the open-label extension, 1,051 patients received ≥1 reslizumab dose (480 reslizumab-naïve, 571 reslizumab-experienced); median (range) exposure was 319 (36-840) and 343 (36-863) days in reslizumab-naïve and reslizumab-experienced patients, respectively. Continuous exposure, including during the placebo-controlled studies, was ≥12 months for 740 patients and ≥24 months for 249 patients. The most common AEs were worsening of asthma and nasopharyngitis. Serious AEs affected 78 of 1,051 (7%) patients; 18 of 1,051 (2%) discontinued treatment because of AEs; and there were 3 deaths (all non-treatment-related). Fifteen adult patients (15 of 1,023; 1%) had malignancies of diverse tissue types. Reslizumab-experienced patients maintained improved lung function and asthma control; reslizumab-naïve patients had improvements in these measures throughout open-label treatment. Blood eosinophil counts appeared to be returning to baseline after reslizumab discontinuation.

In patients with moderate-to-severe eosinophilic asthma, intravenous reslizumab 3.0 mg/kg displays favorable long-term safety and sustained long-term efficacy. Initial improvements in lung function and asthma control were maintained for up to 2 years. These findings substantially add to our understanding of the long-term safety and efficacy of anti-IL-5 strategies.