Reslizumab improves FVC and FEF25%-75% in severe eosinophilic asthma: results from a pooled analysis

RATIONALE: IV reslizumab (RES), a humanized anti-interleukin-5 monoclonal antibody, demonstrated significant improvement in FEV₁ at 52 weeks in patients aged 12–75 years with inadequately controlled asthma and blood eosinophils ≥400 cells/µL (110mL [95% CI: 67, 150mL]) (Castro et al., Lancet Respir Med 2015;3:355–66). It is previously unreported whether reslizumab treatment results in improvement in additional lung function parameters.

METHODS: Data were pooled from two 52-week placebo-controlled trials of IV reslizumab 3mg/kg (Q4wks) in patients with uncontrolled asthma and elevated blood eosinophils (≥400 cells/µL). Outcomes measured included FVC and FEF_25%-75%.

RESULTS: Patients were treated with placebo (n=476) or reslizumab (n=477). Mean treatment difference for reslizumab relative to placebo over 16 and 52 weeks in FVC was 108mL (95% CI: 55, 161; p<0.0001) and 104mL (95% CI: 51, 158; p=0.0001), respectively. At the first scheduled assessment 4 weeks after the first dose, reslizumab treatment resulted in FVC improvement of 128mL (95% CI: 69, 186; p<0.0001) compared with placebo. Mean treatment difference for reslizumab relative to placebo over 16 and 52 weeks in FEF_25%-75% was: 102mL (95% CI: 42, 161; p=0.0008) and 99mL (95% CI: 39, 158; p=0.0012), respectively. There was improvement in FEF_25%-75% as early as 4 weeks: treatment difference 102mL (95% CI: 34, 171; p=0.0034).

CONCLUSIONS: Patients with inadequately controlled asthma and elevated blood eosinophils treated with reslizumab showed clinically meaningful improvement in FVC and FEF_25%-75%. The increase observed may be indicative of a reduction in air trapping and recruitment of small peripheral airways.