Inhibiting C5a/C5aR to treat ANCA-associated vasculitides

Update on targeted treatments for ANCA-associated vasculitis

Targeted therapy has revolutionized the management of ANCA-associated vasculitis (AAV) over the last fifteen years. Rituximab, an approved induction and maintenance agent for severe AAV, is no less effective than cyclophosphamide as induction therapy and particularly useful in relapsing or refractory disease, or in women. In patients with relapsing AAV, granulomatosis with polyangiitis or PR3-ANCA, it is more effective than cyclophosphamide. Rituximab maintenance is superior to the conventional immunosuppressive drugs that it replaces. Low-dose preemptive rituximab infusions are recommended every 6months for 18months, followed by re-evaluation to decide whether 4 additional biannual infusions should be administered, balancing the probability of relapse and the risk of serious infections on rituximab. A growing body of experimental and clinical data shows that C5a pathway inhibition is a promising therapeutic option for AAV, which could reduce glucocorticoids needs. Avacopan is a first approved oral C5A receptor antagonist, used when there is a high risk that glucocorticoids will cause serious adverse events. In eosinophilic granulomatosis with polyangiitis, the importance of IL-5 for eosinophil activation and survival led to evaluation and approval of mepolizumab, a humanized monoclonal antibody directed against IL-5. Mepolizumab showed a steroid-sparing effect. Its effectiveness in active vasculitis remains uncertain and is currently being evaluated. Benralizumab targeting the IL-5 receptor was recently shown to be noninferior to mepolizumab. Rituximab has had disappointing results in non-severe active vasculitis and is being evaluated as maintenance therapy. Plasma exchange is not indicated as first-line treatment but remains recommended when creatinine levels exceed 300μmol/L.