Objectives: To describe the efficacy of conventional immunosuppressants in disease control of relapsing or refractory eosinophilic granulomatosis with polyangiitis (EGPA) compared to recently published mepolizumab and rituximab studies.
Methods: A retrospective analysis from the Toronto Vasculitis Clinic was conducted. Patients with relapsing or refractory EGPA with similar entry criteria as the main mepolizumab (MIRRA) or rituximab (case-series) studies, who were started on conventional immunosuppressants, were assessed for remission at 24- and 52-weeks. Remission was defined as a Birmingham Vasculitis Activity Score of 0 and a prednisone dose of ≤4mg/day, ≤7.5mg/day, corresponding to the mepolizumab trial, or any prednisone dose per day, as in the rituximab study.
Results: Among 110 cohort patients, 24 with relapsing or refractory EGPA met eligibility criteria. Conventional immunosuppressants used were methotrexate (n=15), azathioprine (n=8) or leflunomide (n=1). Remission rates at 24-weeks were 8.3% with prednisone ≤4mg/day (vs. 28.0% in the mepolizumab trial); 41.6% with prednisone ≤7.5mg/day (vs. 45% in the mepolizumab trial) and 62.5% with any prednisone dose (vs. 34% in the rituximab study). Remission at 52-weeks was 50.0% with any prednisone dose (vs. 49% in the rituximab study), whereas sustained remission at week 52 (as of week 24) was 4.2% with prednisone ≤4mg/day (vs. 19% in the mepolizumab trial), and 33.3% with prednisone ≤7.5mg/day (vs. 24% in the mepolizumab trial).
Conclusions: Though our study was small and retrospective, rates of remission observed with conventional immunosuppressants were substantial. This should be kept in mind when interpreting results of placebo-controlled or retrospective studies on biologics in EGPA.