Increase in antibody levels predicts relapse risk in AAV: Study
Scientists say monitoring MPO-ANCA levels could improve care
An increase in blood levels of a self-reactive antibody called MPO-ANCA predicted the return of ANCA-associated vasculitis (AAV) symptoms within months in most patients in a Belgian study.
None of the patients whose MPO-ANCA levels decreased and remained undetectable in blood experienced relapses, data showed.
“Monitoring MPO-ANCA levels in AAV patients in remission could help clinicians to tailor therapy more effectively,” researchers wrote.
The study, “Clinical value at baseline and follow-up of myeloperoxidase-antibodies in ANCA-associated vasculitis,” was published in Frontiers in Immunology.
AAV occurs when a type of self-reactive antibody called ANCA triggers an immune attack on small blood vessels, causing them to become inflamed. This inflammation can damage organs, leading to vasculitis symptoms. The disease can be classified into three AAV types: microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Disease features, as well as treatment, differ among the types.
Predicting who will relapse
While AAV treatment aims to achieve and maintain remission — where there are no symptoms — remission does not always last.
Predicting which patients are more likely to see their symptoms return could improve AAV care and prevent further complications.
ANCAs commonly target myeloperoxidase (MPO) or proteinase 3 (PR3), two proteins found in certain immune cells. While PR3-ANCA is linked to a higher risk of relapse, the role of MPO-ANCA remains less clear. “MPO-ANCA are present in 70% of patients with MPA, 40% with EGPA, and 10% with GPA,” the researchers wrote.
To understand whether changes in MPO-ANCA levels could predict relapse, the team retrospectively reviewed the medical records of 73 AAV patients who tested positive for MPO-ANCA and underwent regular follow-up at Hopital Universitaire de Bruxelles.
All patients had achieved remission, defined by a score of zero (no symptoms) on the standard Birmingham Vasculitis Activity Score (BVAS) and a low dose of prednisone or other standard corticosteroids. A relapse was defined as a BVAS of one or higher after achieving remission.
Twenty-nine people had MPA, 22 had GPA, and 22 had EGPA. “Because EGPA and GPA/MPA patients are now treated differently, these two groups [were] studied separately,” the researchers wrote.
Over a long follow-up period — a median of seven years for the MPA/GPA group and 10 years for EGPA patients — about half of the people had at least one relapse. Nineteen of 51 people with MPA/GPA and 10 of 22 people with EGPA relapsed.
Blood MPO-ANCA levels at the time of AAV diagnosis did not predict who would relapse later. However, an increase in MPO-ANCA levels during follow-up did.
Twelve of the EGPA patients had increasing MPO-ANCA levels during follow-up, and relapses occurred in 10 people in this group. A similar pattern was observed in MPA/GPA, with 19 of the 24 patients with increasing MPO-ANCA levels experiencing a relapse.
The MPO-ANCA level increase usually preceded relapse by an average of 3.6 months for EGPA and 4.6 months for MPA/GPA.
The predictive potential of increasing MPO-ANCA levels was high. In EGPA patients, the positive predictive value — a measure of the probability that a patient with increasing MPO-ANCA relapses later — was 83%. In MPA/GPA, it was 79%.
In contrast, none of the patients whose MPO-ANCA levels decreased and stayed undetectable experienced a relapse during follow-up.
Treatment adjustments were rarely made when MPO-ANCA levels began to increase, with six patients having their corticosteroid dosing increased or another immunosuppressant added before symptoms returned.
“Our results support the predictive value of MPO-ANCA dynamics once remission has been achieved, and confirm their position as a valuable monitoring tool” for AAV, regardless of specific disease type, the researchers wrote. “Indeed, we show that an increase in MPO-ANCA levels is associated with a risk of clinical deterioration, and conversely, persistent negativity indicates a very low (potentially absent) risk of relapse.”
Regular testing could help doctors identify patients at risk earlier and adapt treatment strategies, potentially preventing further damage to the body’s organs.
“Our study lays the foundations for future … multicenter studies [following patients over time], with the ultimate goal of improving patient outcomes by reducing unnecessary exposure to prolonged immunosuppressive treatment and adjusting maintenance regimens as appropriate,” the team concluded.
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