Highlights from the plenary session: eosinophilic granulomatosis with polyangiitis and hypereosinophilic syndrome.

Hypereosinophilic syndrome (HES) and eosinophilic granulomatosis with polyangiitis (EGPA) both present with hypereosinophilia and organ damage induced by eosinophils. EGPA is also characterized by vasculitis and is associated with ANCA. Yet, discriminating HES from EGPA may be difficult in clinical practice as biomarkers to reliably differentiate between HES and EGPA are still lacking. In recent years, it has been demonstrated that targeting IL-5 is efficacious to treat HES and EGPA, and the use of anti-IL-5(R)-antibodies has become a mainstay of therapy in HES and these diseases. Nonetheless, it remains unclear whether anti-IL-5 strategies are sufficient to treat organ-threatening eosinophilic manifestations or vasculitic manifestations in EGPA.