Improved small airway function by benralizumab in patients with severe eosinophilic asthma

Benralizumab improves asthma control and lung function in patients with severe eosinophilic asthma, but the effect on the small airways has not been described. We determined changes in small airway function by forced oscillation technique (FOT) and multiple breath nitrogen washout (MBNW) in relation to symptom improvement. Patients with severe asthma commencing benralizumab had measurements at week 0, week 4, and week 24 including: 5-item Asthma Control Questionnaire (ACQ-5), spirometry, MBNW, and FOT at 5Hz. All other asthma treatment was kept constant for 4 weeks. Changes between visits and relationship with ACQ-5 were assessed using non-parametric tests, prediction of symptom improvement using receiver-operating-characteristics (ROC). 12 patients (7 males) aged 46±17yrs (mean±SD), BMI 26±5kg/m2, eosinophil count 1.0±0.4x10-9/L, and FEV1 62±20% predicted were studied. At week 4, eosinophil count was undetectable and ACQ-5 improved significantly (2.6±1.0 to 1.4±1.0, p 0.65, p In this cohort, small and large airway function improved soon after commencing benralizumab and predicted symptom improvement reported by patients. Physiological phenotyping may help identify patients most likely to benefit from treatment.