As Tsurikisawa et al. reported that GC or immunosuppressive drugs could be reduced in 20patients (66.7%) of EGPA with higher eosinophil counts at diagnosis [13], patients with marked eosinophilia are likely to have a better outcome because the condition is more likely to demonstrate the effect of IL-5 inhibition, the mechanism of action of mepolizumab. This evidence concerns the gene IL5 and eosinophilic granulomatosis with polyangiitis.