Reslizumab for Inadequately Controlled Asthma with Elevated Blood Eosinophil Levels: a Randomized Phase 3 Study

BACKGROUND: This phase 3 study further characterizes the efficacy and safety of reslizumab (a humanized anti-interleukin-5 monoclonal antibody) in patients aged 12-75 years with asthma inadequately controlled by at least a medium-dose inhaled corticosteroid, and blood eosinophils ≥400cells/μL.

METHODS: Patients were randomized to receive reslizumab 0.3 or 3.0mg/kg or placebo once/every 4 weeks/16 weeks. Primary endpoint was change from baseline in pre-bronchodilator forced expiratory volume in 1 sec (FEV1) over 16 weeks. Secondary endpoints included forced vital capacity (FVC), forced expiratory flow at 25-75% of FVC (FEF25-75%), patient-reported control of asthma symptoms, short-acting beta agonist (SABA) use, blood eosinophil levels, and safety.

RESULTS: Reslizumab significantly improved FEV1 (difference vs placebo [reslizumab 0.3 and 3.0mg/kg]:115mL[95% CI 16-215; P= .0237] and 160mL[95% CI 60-259; P= .0018]). Clinically meaningful increases in FVC (130mL) and FEF25-75% (233mL/s) were observed with reslizumab 3.0mg/kg. Reslizumab improved Asthma Control Questionnaire (ACQ) and Asthma Quality of Life Questionnaire (AQLQ) versus placebo (greater effects seen with 3.0mg/kg; P<0.05). The minimally important difference was reached for AQLQ (reslizumab 3.0mg/kg) but not ACQ. Asthma Symptom Utility Index and SABA use were improved with reslizumab. The most common adverse events were asthma worsening, headache, and nasopharyngitis; most were mild-to-moderate in severity.

CONCLUSIONS: Reslizumab improved lung function, asthma control and symptoms, and quality of life, and was well tolerated in patients with inadequately controlled asthma (despite standard therapy), and elevated blood eosinophils. Overall, the 3.0mg/kg dose of reslizumab provided greater improvements in asthma outcomes (vs 0.3mg/kg), with comparable safety.