IL13 and asthma: We have examined the value of a composite biomarker strategy using FeNO, blood eosinophils, and serum periostin together to predict exacerbation risk in the placebo arms of clinical trials with lebrikizumab (anti-IL-13) and omalizumab (anti-IgE) in patients taking at least 500 μg fluticasone propionate (FP) and a second asthma controller [23–25].