In patients with severe asthma with eosinophilia in reslizumab clinical trials, high peripheral blood eosinophil levels are associated with low FEV(1) reversibility

BACKGROUND: A post hoc analysis of two randomized, placebo–controlled, Phase 3 trials of intravenous reslizumab, an anti-interleukin-5 (IL-5) biologic for severe eosinophilic asthma. METHODS: Relationships between baseline blood eosinophil levels (EOS), forced expiratory volume in 1 s (FEV(1)) reversibility to β(2)-agonists and treatment outcomes were assessed. RESULTS: Mean baseline FEV(1) reversibility was numerically lower among patients with high (≥ 400 cells/µL) versus low baseline EOS. Reslizumab produced clinically significant improvement in FEV(1), exacerbation rates and patient-reported outcomes after 52 weeks, including in patients with high EOS and low FEV(1) reversibility (≤ 14%) to β(2)-agonists at baseline. CONCLUSIONS: Clinical trial eligibility criteria stipulating minimum FEV(1) reversibility to β(2)-agonists of ≥ 12% might exclude patients who would benefit from treatment with anti-IL-5 biologics.