What is ANCA-associated vasculitis?

ANCA-associated vasculitis is a group of autoimmune conditions in which the immune system attacks blood vessels, particularly small blood vessels. The inflammation damages the affected vessels and the organs they supply. The conditions are grouped together because they share an autoimmune feature called ANCA (anti-neutrophil cytoplasmic antibodies) and similar treatment approaches.

The three main forms.

Granulomatosis with polyangiitis (GPA, formerly Wegener granulomatosis): often involves the upper airway (sinuses, nose, ears), lungs, and kidneys.

Microscopic polyangiitis (MPA): often involves the kidneys and lungs without upper airway involvement.

Eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss syndrome): often involves asthma, eosinophilia (high blood eosinophil count), and vasculitis affecting various organs.

Why it can affect multiple organs. Small blood vessels supply nearly every part of the body. When the immune system attacks them, the result depends on which organs the affected vessels are supplying. Common manifestations include kidney inflammation (which can cause kidney failure), lung inflammation (with bleeding or breathing problems), nerve inflammation (causing numbness or weakness), skin involvement, and others. The diagnosis often requires a combination of clinical features, ANCA blood test, and biopsy of an affected organ.

The traditional therapy. For decades, treatment was high-dose corticosteroids plus cyclophosphamide chemotherapy for severe disease. This regimen was effective but caused substantial side effects, particularly with cumulative cyclophosphamide exposure (infections, bone marrow problems, infertility risk, secondary cancer risk). The need for less toxic options drove the modern therapy approach.

The modern therapy.

Rituximab: an antibody that depletes B cells (the immune cells that produce ANCA antibodies). Rituximab is now the preferred agent for both inducing remission in severe disease and maintaining remission with scheduled maintenance dosing. It is comparable in effectiveness to cyclophosphamide for induction but with a better safety profile.

Avacopan: a medicine that blocks the C5a receptor, an immune signal that recruits inflammatory cells to blood vessels. Avacopan is approved for severe active ANCA-associated vasculitis and substantially reduces the glucocorticoid dose needed for induction therapy. Lower cumulative glucocorticoid dose means fewer steroid-related side effects (infections, bone loss, blood sugar problems, skin and other changes).

Maintenance therapy: scheduled rituximab maintenance for 18 to 24 months or longer is the modern standard. It substantially reduces relapse risk compared to older approaches.

For EGPA specifically: mepolizumab (an anti-IL-5 medicine) carries EGPA approval and is now widely used as part of management, particularly for the asthma and eosinophilic components. Benralizumab has reported positive pivotal data in EGPA.

The emerging direction. BAFF-targeted programs, JAK pathway programs, and additional complement-pathway programs are in late-stage trials, with the goal of further reducing the cumulative steroid dose and improving long-term outcomes.

What to expect. ANCA-associated vasculitis is a serious condition but is increasingly well-managed with the modern combination of rituximab, avacopan in severe disease, and scheduled maintenance therapy. With appropriate care from a specialist (typically rheumatology, with nephrology, pulmonology, or other specialty input as needed), most patients can achieve and maintain remission with substantially fewer steroid-related complications than the older approach.