Supplementary Material for: Long-term safety, clinical and immunological outcomes in Primary Membranous Nephropathy with Severe Renal Impairment treated with cyclophosphamide and steroid-based regimen

Introduction and Aims Therapy of Primary Membranous nephropathy (PMN) with progressive advanced kidney dysfunction is challenging with limited literature and no clear therapeutic strategies. This is due to the scant evidence of effectiveness and uncertainty around the risk-benefit profile of immunosuppression (ImS) when eGFR is less than 30 ml/min. We aimed to determine long term clinical outcomes in patients with PMN and severe renal impairment treated with combined cyclophosphamide and steroids. Methods The study is a single-centre retrospective longitudinal cohort study. All patients (between 2004-2019) with biopsy confirmed PMN who initiated combination therapy with steroids and cyclophosphamide and had an eGFR of ≤30ml/min/1.73m2 at the time of initiation of therapy were included for analysis. Clinical and laboratory parameters including Anti-PLA2R-Ab were monitored as per standard clinical guidance. Primary outcome was achievement of partial remission. Secondary outcomes included immunological remission, need for renal replacement therapy, and adverse effects. Results Eighteen patients with median age of 68 (IQR 58-73) years and 5:1 M:F ratio received the combination therapy when eGFR was ≤30ml/min/1.73m2 (CKD-EPI). At time of immunosuppression, median eGFR and uPCR were 23 (IQR 18-27) ml/min/1.73m2 and 1000 (IQR 838-1285) mg/mmol respectively. Median follow-up was for 67 (IQR 27-80) months. 16 patients (89%) achieved partial Remission and 7 (39%) achieved complete remission. eGFR increased by 7ml/min/1.73m2 (27%) after one year of starting immunosuppression treatment and 12ml/min/1.73m2 at end of follow-up. Two patients (11%) developed end stage renal disease needing renal replacement therapy. 67% achieved both immunological and clinical remission. Two (11%) patients required hospitalization secondary to infections, 4 (22%) patients developed cancer and 4 patients died (22%). Conclusion Combination therapy with cyclophosphamide and steroids is effective in achieving partial remission and improving renal function in PMN with advanced renal dysfunction. Prospective controlled studies are required to provide further evidence and improve outcomes in such patients.