Early add-on administration of mepolizumab and intravenous immunoglobulin effective in treating eosinophilic granulomatosis with polyangiitis.

Treatment of eosinophilic granulomatosis with polyangiitis (EGPA) remains a challenge because currently available therapies, corticosteroids and immunomodulators, do not always control symptoms and are often associated with significant morbidity and relapse. Mepolizumab has been demonstrated to be an effective add-on therapy with steroid-sparing effect in cases of relapsing or refractory EGPA. Intravenous immunoglobulin (IVIG) therapy is effective against mononeuritis multiplex or heart failure in patients with EGPA who do not respond to corticosteroid-cyclophosphamide treatment. We present two cases of EGPA in which earlier add-on administration of adjunct mepolizumab and IVIG led to significant improvement in EGPA symptoms and prevention of flare-up of the disease. We suggested that earlier add-on combination administration of IVIG and mepolizumab might be a useful adjunct treatment to induce clinical remission of EGPA and improve the rate of remission, decrease relapse rate, and allow for reduced glucocorticoid use without any serious adverse drug effects.