Antineutrophil cytoplasmic antibody (
ANCA)-associated vasculitis (AAV) comprises several clinical entities with diverse clinical presentations, outcomes, and nonunifying pathogenesis. AAV has a clear potential for relapses, and shows unpredictable response to treatment.
Cyclophosphamide-based
therapies have remained the hallmark of induction
therapy protocols for more than four decades. Recently, B-cell depleting
therapy with the anti-CD20 antibody
rituximab has proved beneficial in AAV, leading to Food and Drug Administration approval of
rituximab in combination with
corticosteroids for the treatment of AAV in adults.
Rituximab for
ANCA-associated vasculitis and other clinical trials provided clear evidence that
rituximab was not inferior to
cyclophosphamide for
remission induction, and
rituximab appeared even more beneficial in patients with relapsing disease. This raised hopes that other B-cell-targeted
therapies directed either against CD19, CD20, CD22, or B-cell survival factors,
B-cell activating factor of the
tumor necrosis factor family (BAFF) and a proliferation-inducing
ligand could also be beneficial for the management of AAV. BAFF neutralization with the fully humanized
monoclonal antibody belimumab has already shown success in human
systemic lupus erythematosus and, along with another anti-BAFF
reagent blisibimod, is currently undergoing Phase II and III clinical trials in AAV. Local production of BAFF in granulomatous lesions and elevated levels of serum BAFF in AAV provide a rationale for BAFF-targeted
therapies not only in AAV but also in other forms of
vasculitis such as
Behcet's disease, large-vessel
vasculitis, or cryoglobulinemic
vasculitis secondary to
chronic hepatitis C infection. BAFF-targeted
therapies have a very solid safety profile, and may have an additional benefit of preferentially targeting newly arising autoreactive B cells over non-self-reactive B cells.