This remarkable observation was confirmed in a five-year extension study when exacerbations were eliminated in 60% of patients who had initial blood eosinophils > 300 cells/μL while on medium-to-high-dose inhaled corticosteroids, opening the possibility of blood eosinophils serving as a biomarker for “asthma clinical remission” on anti-IL-5 therapy [46]. Here, IL5 is linked to asthma.