Targeted
immunotherapy is substantially improving the management of
ANCA-associated vasculitides (AAV), which include
granulomatosis with polyangiitis (GPA,
Wegener's granulomatosis),
microscopic polyangiitis (MPA), and
eosinophilic granulomatosis with polyangiitis (EGPA,
Churg-Strauss syndrome). This article reviews the current role for targeted
immunotherapy in AAV, its validated indications, and avenues for further development.
Rituximab is a validated induction treatment for GPA and severe MPA.
Rituximab in these indications is not less effective than
cyclophosphamide and is particularly useful in patients with refractory or relapsing disease, women of childbearing potential, and patients previously treated with
cyclophosphamide.
Rituximab is more effective than
cyclophosphamide for treating relapses. For remission maintenance
therapy, which is indispensable,
rituximab has been proven superior over conventional immunosuppressive treatment.
Rituximab is licensed in the USA and in Europe for the induction treatment of severe forms of GPA and MPA. An extension study for remission maintenance
therapy is ongoing. In EGPA, although maintenance treatment with the
interleukin-5 antagonist
mepolizumab is effective in decreasing
glucocorticoid requirements and in alleviating
asthma and sinonasal symptoms, its efficacy on the
vasculitis remains somewhat unclear.
Mepolizumab is licensed for use in EGPA, and
rituximab is also being evaluated as an induction and maintenance agent.
Immunoglobulins can be helpful as an adjuvant treatment for active AAV with severe immunedepression, notably when
infections occur.
Plasma exchange is indicated in AAV with advanced renal dysfunction and, perhaps, in the event of alveolar
hemorrhage, a possibility that will be assessed in 2018 in a large international study.