Dupilumab was added when there were clinical signs of uncontrolled IL4/IL13 inflammation, driving asthma pathology even under an anti-IL5 monoclonal antibody (mAB): elevated FeNO, airway smooth muscle dysfunction, and severe airway hyperresponsiveness (AHR) with significant postbronchodilator reversibility (pBDR). Here, IL4 is linked to asthma.