Background/Purpose: Eosinophilic granulomatosis with polyangiitis (EGPA) is characterized by systemic necrotizing vasculitis affecting small and medium-sized vessels, and defined by the presence of eosinophilia, extravascular granulomas, and eosinophil tissue infiltration.Mepolizumab (MPZ), the first anti-interleukin-5 monoclonal antibody proven effective and safe in the MIRRA clinical trial, has been widely used to treat patients with EGPA. Therefore, it is pertinent to analyze all published data from real world studies to better understand the effectiveness and safety of MPZ in clinical practice setting.We aimed to conduct a systematic review of all published clinical research on the real world effectiveness and safety of 300 mg MPZ treatment in patients with EGPA

Methods: A systematic literature review was conducted to identify studies reporting data on the effectiveness and safety of MPZ in patients with EGPA in a real world setting, included in OVID, Medline, and EMBASE databases, covering articles published by November 2024.This review encompassed studies that reported data on MPZ at the Food and Drug Administration and European medicines Agency approved dose of 300 mg.

Results: Involving a total of 2,639 patients, 14 studies provided specific data on those receiving 300 mg of MPZ, including prospective, ambispective, or retrospective designs, with follow-up periods from 3 to 48 months. Remission rates ranged from 37.9% to 82.0% at 12 months, from 58,3% to 72.7% at 24 months, and stabilized 64% at 48 months.Treatment with 300 mg MPZ led to a significant reduction in disease activity, as assessed by BVAS, which decreased from 17 to 0 at both 3 and 6 months in one study, and from 4 to 0 at 6, 12, and 24 months in another study. The annualized rate of EGPA-related hospitalizations decreased from 0.54 to 0.02 events/person-year at 48 months. The proportion of patients without immunosuppressive therapy rose to 79% during the 48 months follow up period. No significant differences in Vascular Damage Index score at 12 months were observed, suggesting that MPZ therapy was effective in controlling organ damage progression. Additionally, there was a reduction in glucocorticoid (GC) use, with GC discontinuation rates of up to 41.7% at 24 months and a reduction in GC doses to ≤ 4 mg/day in up to 68% in all the identified articles. The blood eosinophil counts decreased significantly, reaching counts ranging 55-100 cell/μl. A significant reduction in the proportion of ANCA-positive patients was also observed after treatment with MPZ 300 mg. In terms of safety, MPZ was well-tolerated with adverse events reported primarily as mild to moderate upper respiratory tract infections. The overall rate of MPZ retention was 100% at 6 months and ranged from 90% to 100% at 12 months.

Conclusion: This systematic review of the published evidence on MPZ 300 mg in real-world clinical practice confirms significant clinical benefits from patients with EGPA by improving remission rates, reducing GC dependence, and decreasing disease activity, maintaining a favorable safety profile. These results complement data from clinical trials

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/beyond-clinical-trials-in-eosinophilic-granulomatosis-with-polyangiitis-a-systematic-review-of-effectiveness-and-safety-data-derived-from-real-world-evidence-of-mepolizumab-300-mg/