METHODS: This post hoc analysis included patients with moderate or severe persistent allergic asthma from the 16-week inhaled corticosteroid dose-stable phase of two phase III clinical trials of omalizumab. For this analysis, asthma exacerbations were defined as the number of events requiring ≥3 days of systemic corticosteroids. Asthma exacerbation rates for omalizumab versus placebo were evaluated with respect to baseline blood eosinophil counts using a wide range of cutpoints (≥0, 100, 200, 300, 400/μL) to define subgroups. P-values and 95% confidence intervals (CI) for comparisons of exacerbation rates were calculated using unadjusted negative binomial models.
RESULTS: A total of N=1071 adults/adolescents (≥12 years) were randomized to receive either omalizumab (n = 542) or placebo (n = 529). The overall relative exacerbation rate reduction for omalizumab versus placebo was 57% (95% CI, 34–71%; P < 0.001). Exacerbation rate reductions were significant across a wide range of eosinophil levels (≥0: 56% (95%CI 33%, 71%; p=0.0002), ≥100: 57% (95%CI 33%, 72%; p=0.0002), ≥200: 55% (95%CI 25%, 73%; p=0.002), ≥300: 67% (95%CI 36%, 84%; p=0.001), ≥ 400: 74% (95%CI 40%, 88%; p=0.001).
CONCLUSIONS: In patients with moderate or severe persistent allergic asthma, response to omalizumab is observed across a wide range of eosinophil levels.