Reslizumab in patients with inadequately controlled late-onset asthma and elevated blood eosinophils

Asthma with adult onset and elevated blood eosinophils is a difficult-to-treat subgroup. This post hoc analysis evaluated reslizumab, an anti-interleukin-5 monoclonal antibody, in patients with late-onset eosinophilic asthma. Data from two 52-week placebo-controlled trials of reslizumab IV 3 mg/kg every 4 weeks in patients aged 12–75 years with inadequately controlled asthma, ≥1 asthma exacerbation within 12 months, and screening blood eosinophils ≥400/μL (NCT01287039/NCT01285323) were stratified by age of asthma onset (<40 or ≥40 years). Annual clinical asthma exacerbation rates, change in lung function, and patient-reported outcomes were analyzed. 273 patients with late-onset asthma (placebo, n = 130; reslizumab, n = 143) and 658 with early-onset asthma (placebo, n = 336; reslizumab, n = 322) were included. Baseline demographics were similar between groups. The interaction between age at onset of asthma and effect of reslizumab on asthma exacerbations was statistically significant (p = 0.0083). Compared with placebo, reslizumab produced a 75% relative reduction in asthma exacerbations in patients with late-onset asthma (rate ratio [RR] 0.25; 95% confidence interval [CI], 0.16, 0.40), substantially larger than the reduction in earlier onset patients (RR 0.58; 95% CI, 0.44, 0.76). Similar findings were observed for other measures of asthma, including forced expiratory volume in 1 s (FEV1). The adverse event profile of reslizumab was similar in patients with early- or late-onset asthma. Compared with placebo, reslizumab produced larger reductions in asthma exacerbations and larger improvements in lung function in patients with late versus early-onset asthma.