Blood eosinophils and FeNO are prognostic and predictive biomarkers in childhood asthma

BACKGROUND:Blood eosinophils and fractional exhaled nitric oxide (FeNO) are prognostic biomarkers for exacerbations and predict responses to dupilumab in adolescents and adults with asthma. OBJECTIVE:To evaluate the relationship between baseline blood eosinophils and FeNO and response to dupilumab in children with asthma. METHODS:Children aged 6 to 11 years with uncontrolled moderate-to-severe asthma (n = 408) were randomized to receive dupilumab 100/200 mg by body weight, or volume-matched placebo every 2 weeks for 52 weeks. Annualized exacerbation rate (AER) reduction and least squares (LS) mean change in pre-bronchodilator percent predicted forced expiratory volume in 1 second (ppFEV1) at Week 12 were assessed according to cutoff baseline levels for FeNO (<20 ppb vs ≥20 ppb) and blood eosinophil count (<150, ≥150-<300, ≥300-<500, and ≥500 cells/μL). Quadrant analyses in populations defined by biomarker thresholds and spline models across continuous endpoints assessed the relationship with FeNO and eosinophil count. Interaction testing evaluated the independent roles of FeNO and blood eosinophils as predictive markers. RESULTS:Exacerbation risk and magnitude of AER reduction increased in subgroups with higher baseline biomarker levels. Quadrant analyses showed that patients with either elevated FeNO or eosinophil counts demonstrated a clinical response to dupilumab. Interaction testing indicated blood eosinophil counts or FeNO independently added value as predictive biomarkers. CONCLUSIONS:In children with uncontrolled moderate-to-severe asthma, blood eosinophil counts and FeNO are clinically relevant biomarkers to identify those at risk for asthma exacerbations, as well as those who will demonstrate a clinical response to dupilumab.