Background: Patients with idiopathic membranous nephropathy (iMN) and renal insufficiency have a high risk for progression to end-stage renal disease (ESRD). In the short term, treatment with oral cyclophosphamide and steroids attenuates the deterioration of renal function in these patients; however, the long-term efficacy is unknown.
Methods: We have studied prospectively 65 patients with iMN and renal insufficiency (serum creatinine >135 micromol/l) who were treated with oral cyclophosphamide (1.5-2.0 mg/kg/day for 12 months) and steroids (methylprednisolone pulses 3 x 1 g, i.v. at months 1, 3 and 5, and oral prednisone 0.5 mg/kg/48 h for 6 months).
Results: Follow-up was 51 (5-132) months. Renal function temporarily improved or stabilized in all patients. A partial remission (PR) occurred in 56 patients followed by a complete remission (CR) in 17. During follow-up, 11 patients had relapsed (28% relapse rate after 5 years), of whom nine were re-treated because of renal function deterioration. At the end of follow-up, 16 patients were in CR, 31 in PR, eight had a persistent nephrotic syndrome, one had mild proteinuria, four had progressed to ESRD and five had died. Overall renal survival was 86% after 5 years and 74% after 7 years, compared with 32% after 5 and 7 years in a historical control group. Treatment-related complications occurred in two-thirds of patients, mainly consisting of bone marrow depression and infections. One patient has developed bladder cancer, another patient prostate cancer.
Conclusions: Renal survival is good if patients with iMN and renal insufficiency are treated with oral cyclophosphamide. However, side effects occur frequently and relapse rate is high during longer follow-up.