#1739 Combination Rituximab & Low-Dose IV Cyclophosphamide Induction Therapy for Severe Multi-System Eosinophilic Granulomatosis with Polyangiitis

Abstract Background and Aims Current guidelines advise rituximab (RTX) or cyclophosphamide treatment for organ-threatening disease in eosinophilic granulomatosis with polyangiitis (EGPA). However, conventional treatment is often limited by partial efficacy, toxicity, high relapse rate and steroid dependency. We investigate the use of a combined RTX, low-dose cyclophosphamide, and steroid regimen for treatment of severe EGPA. Method Single-centre retrospective cohort study of patients treated with a combination induction regimen for severe EGPA (with kidney, cardiac or neurological involvement) between 2012-23. Data reported as median (±IQR) Results Eighteen patients (10 male; age 56 years [52-62]) are included. At treatment, BVAS was 16.3 [14-20], peak eosinophil count 9.3 × 109/L [5-13], C-reactive protein (CRP) 122 mg/L [80-193]. Eleven cases were ANCA positive (10 MPO-, 1 PR3-ANCA.) The proportions of patients affected by active/new respiratory, ENT, neurological, and gastrointestinal disease were 18/18 (100%), 14/18 (78%), 11/18 (61%), and 1/18 (6%), respectively. 11/18 (61%) had cardiac involvement (troponin 10345 ng/L [1240-7621]) and 6/18 (33%) had necrotising glomerulonephritis confirmed by renal biopsy (creatinine 123 µmol/L [83-167]). Cumulative cyclophosphamide dose was 3.5g [3.0-3.5] and total RTX dose was 2g. Initial prednisolone dose was 0.5-1.0 mg/kg/day, and this was rapidly weaned to 5 mg daily at a median time of 6.1 months [3.9-7.2], and 9/18 (50%) had steroids withdrawn completely by 11.7 months [4.6-20.6]. First-line maintenance treatment was azathioprine or MMF. By 6 months, all achieved disease remission as assessed by BVAS (all 0) and improved laboratory parameters: CRP 1 mg/L, eosinophil count 0.1 × 109/L, and ANCA testing negative. In those with renal disease, kidney function improved or stabilised in all (creatinine 95 µmol/L). In those with cardiac disease (11/18), magnetic resonance imaging was performed at baseline and at follow up (median time of 3.7 months) in all patients. Of these, 9/11 (82%) had oedema on initial scan and this improved in all cases; 10/11 (91%) had late gadolinium enhancement at baseline, which persisted in every case, though with significantly lower burden. The median follow-up period was 38 months [14-55]. At 1, 3 and 5 years, 100%, 92% and 76% of patients were in sustained remission (Fig. 1A). Three patients experienced relapse; one patient had major relapse with skin involvement requiring reinduction treatment; two patients had minor ENT relapse requiring retreatment with glucocorticoids. Infection-free survival at 1, 3 and 5 years was 94%, 78%, 62%, respectively (Fig. 1B). There were no deaths. Conclusion This regimen provided rapid disease control in patients with severe multi-system EGPA, including those with life-threatening cardiac manifestations, and enabled rapid glucocorticoid tapering and withdrawal. Disease-free remission was sustained during long-term follow up. Combination induction regimens may have a role in the treatment of organ-threatening disease in EGPA.