Concurrent Use of Mepolizumab and Rituximab for Eosinophilic Granulomatosis With Polyangiitis and Multisystem Involvement.

Eosinophilic granulomatosis with polyangiitis (EGPA), formerly Churg-Strauss, is an anti-neutrophil cytoplasmic antibody (ANCA)-associated autoimmune vasculitis, involving small- and medium-sized arteries, which could involve several organs. This rare syndrome can present with a myriad of symptoms, which may make diagnosis challenging. It has been suggested that there are variants of EGPA, which may respond differently to available modes of treatment. Multiple and different mechanisms may be at play in each case of EGPA. This may influence the decision of clinicians to combine treatment strategies as done in this case. The addition of immunosuppressive agents other than high-dose steroids may mitigate end-organ damage, facilitate faster recovery, and prevent relapse. Rituximab among others has been seen to provide better outcomes, including a lower incidence of relapse. Mepolizumab was approved by the Food and Drug Administration (FDA) in 2017 for the treatment of EGPA. Administered at a higher dose than approved for severe eosinophilic asthma, it has been shown to lengthen remission in EGPA. The optimal dose and duration of therapy with mepolizumab remain unclear. The rarity alone of EGPA creates room for further investigation regarding pathogenesis, outcome over time, and treatment strategies, which may vary depending on how an individual case presents. This case describes the course of a 55-year-old woman who presented with respiratory symptoms, pauci-immune necrotizing granulomatous nephropathy, and neuropathy secondary to P-ANCA-positive EGPA who was successfully treated with rituximab and mepolizumab, in addition to glucocorticoids.