Table 1.

Main biological therapies in EGPA (36–68, 71–79).

Drug	Pathogenetic basis	Evidence in EGPA	Dose	Clinical use
Rituximab (36–56)	Anti-CD20—B cell differentiation and B-T cell stimulation ◼ ANCA pathogenetic antibodies ◼ Eosinophils maturation and survival promoted by IL-5 (B-T cell interaction) ◼ IgG4 (a surrogate of B-lymphocyte activation) infiltration of the organs involved	◼ Case reports and open label studies ◼ Previous AAV studies (not involving EGPA) ◼ Two phase 3 RCT ongoing in EGPA:  - REOVAS (RTX as induction therapy) (NCT02807103)  - MAINRITSEG (RTX as maintenance therapy) (NCT03164473)	◼ Induction: 375 mg/m2/week for 4 weeks or 1 g every 2 weeks (AAV treatment) ◼ Maintenance: 500 mg every 6 months for almost 18 months	RCTs ongoing: ◼ New diagnosis or refractory/remitting disease ◼ GC sparing agent
Mepolizumab (57–68)	Anti-IL-5—eosinophils activation and survival ◼ Eosinophils products: massive tissue toxicity ◼ EGPA eosinophils: lower expression of pro-apoptotic genes and defective apoptosis	◼ FDA approval in 2017 as the first specific drug for EGPA (RTC involving 136 patients with uncontrolled non-severe disease) ◼ Long term efficacy: ongoing RCT (NCT03298061)	◼ 300 mg/month (FDA approved) ◼ 100 mg/month (severe eosinophilic asthma, under evaluation in EGPA)	◼ Non-severe relapsing/refractory disease
Omalizumab (71–79)	Anti-free circulating IgE ◼ Lower mast cells activation and interaction with eosinophils ◼ Inhibition of Th2 and IgE mediated antigen presenting processes	Evidence contradictory and scarce: ◼ Positive results in EGPA with asthma resistant to GC ◼ Scarce information about vasculitic involvement ◼ Possible trigger factor for EGPA	◼ Subcutaneously every 2–4 weeks	◼ Maintenance therapy in patients with uncontrolled and severe asthma/ENT symptoms but with a complete control of non-allergic symptoms