In patients with severe asthma with eosinophilia in reslizumab clinical trials, high peripheral blood eosinophil levels are associated with low FEV1 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 (FEV1) reversibility to beta(2)-agonists and treatment outcomes were assessed. Results Mean baseline FEV1 reversibility was numerically lower among patients with high (>= 400 cells/mu L) versus low baseline EOS. Reslizumab produced clinically significant improvement in FEV1, exacerbation rates and patient-reported outcomes after 52 weeks, including in patients with high EOS and low FEV1 reversibility (<= 14%) to beta(2)-agonists at baseline. Conclusions Clinical trial eligibility criteria stipulating minimum FEV1 reversibility to beta(2)-agonists of >= 12% might exclude patients who would benefit from treatment with anti-IL-5 biologics.