Background/Purpose: Contrary to Western countries, MPO-ANCA-associated vasculitis (MPO-AAV) is dominant in Japan or Asian countries. It is possible that therapeutic responses to EGPA with mepolizumab (MPZ) are different in Asian countries. In addition, there have been few reports on the course of long-term treatment of EGPA with MPZ. We conducted a retrospective analysis of the clinical database of the 25 patients of EGPA treated with MPZ in our hospital for remission induction or remission maintenance.

Methods: Twenty-five EGPA patients [19 females and 6 males. 11 MPO-ANCA positive and 14 MPO-negative.] have been treated with MPZ and followed for at least two years since 2018 in the department of Nephrology and Rheumatology in Kyorin University Hospital. They were analysed for clinical courses, including dose of administered corticosteroids (GC) and rates of flare-up. Remission was defined as Birmingham Vasculitis Activity Score (BVAS) was 0. Disease flare-up was defined as a state the disease activity increased and required intensification of immunosuppressive therapy.

They were divided into patients who were administered MPZ within 3 months of onset (early administration group) and who were started administration of MPZ during maintenance therapy at least 3 months after onset (during maintenance group).

Results: Of the 25 patients administered MPZ, 6 patients were categorized as the early administration group (1 male and 5 females; 4 patients were ANCA-positive and 2 patients were ANCA-negative) and the other 19 patients were categorized as the during maintenance group (5 males and 14 females; 7 patients were ANCA-positive and 12 patients were ANCA-negative). Mean ages at onset of groups of the early administration and the during maintenance were 52.2 and 55.0 years old, respectively.

In addition to GC and MPZ, cyclophosphamide (CY) was used in 17% (1/6) of the early group and in 53% (10/19) of the maintenance group.

After two years of therapy, mean doses of GC of each group were 1.7±2.1mg/day and 3.6±2.7mg/day, respectively. The achievement rates of GC dose below 5mg/day after two years treatment of the early group and the maintenance group were 100% and 47% (9/19), respectively. While no flare-up was observed in the early group, 26% (5/19) of the maintenance group developed flare-up after the start of MPZ therapy. These results were similar regardless of ANCA positivity. The incidence of serious infections requiring hospitalization and death after starting MPZ were 0 in both groups.

Conclusion: These results showed that long-term use of MPZ was effective and had an acceptable safety profile in EGPA patients. The use of MPZ from early stage might be recommended because the start of MPZ within 3 months of onset might reduce the dose of GCs after two years of therapy and the flare-up rate.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/analysis-of-clinical-outcomes-in-eosinophilic-granulomatosis-with-polyangiitis-egpa-treated-with-mepolizumab-over-2-years-for-remission-induction-or-maintenance-a-single-center-experience-in-japan/