Reslizumab is a humanised monoclonal antibody that binds specifically to interleukin-5 (IL-5), a major cytokine responsible for the differentiation, maturation, recruitment and activation of eosinophils. The biological function of IL-5 is blocked, thereby reducing the survival and activity of eosinophils.
Reduction in asthma exacerbations
Patients were randomised to receive reslizumab 3mg/kg by iv infusion or placebo every four weeks for one year. The primary outcome measure was the annual frequency of clinical asthma exacerbations.
In a pooled analysis of both studies, the annual rate of asthma exacerbations in patients receiving reslizumab was reduced by 54% compared with those receiving placebo (rate ratio 0.46 [95% CI 0.37—0.58], p<0.0001).
Improvement in FEV1 was also significantly greater in patients receiving reslizumab than in those receiving placebo (0.23L and 0.22L vs 0.11L and 0.12L at 16 and 52 weeks, respectively [p < 0.0001 for both]).
Another phase III study evaluated the efficacy and safety of reslizumab 0.3mg/kg and 3mg/kg in 315 patients with asthma inadequately controlled by at least a medium-dose inhaled corticosteroid and eosinophils ≥400 cells per µL.
The change in FEV1 from baseline to 16 weeks was significantly greater with reslizumab than with placebo (difference: 0.3mg/kg, 115mL [95% CI 16—215]; p=0.0237; 3mg/kg, 160mL [95% CI 60—259]; p=0.0018).
In all three studies reslizumab was superior to placebo in terms of patient-reported measures of asthma control and quality of life.
Raised blood creatine phosphokinase was reported as the most frequently occurring adverse effect.