Efficacy of mizoribine followed by low-dose prednisone in patients with idiopathic membranous nephropathy and nephrotic-range proteinuria.

BACKGROUND: Idiopathic membranous nephropathy (IMN) patients with persistent high-grade proteinuria are at the highest risk for developing end-stage renal failure. We previously reported the effects of treatment with mizoribine followed by low-dose prednisone treatment in 4 IMN patients. The purpose of the present study was to further assess the effects of this combined treatment in a larger study group.

METHOD: Thirteen patients with IMN and nephrotic-range proteinuria received combined treatment. Mizoribine was initiated at a dose of 150 mg/day, and 2-3 months later, 20 mg/day prednisone was added to the mizoribine regimen. The dosage of prednisone and/or mizoribine was tapered according to the urinary protein-to-creatinine ratio (P/C). We evaluated patient responses for up to 12 months after the initiation of combination therapy.

RESULTS: Before treatment, patient urinary P/C ranged from 3.7 to 15.9 g/g. Although these values did not decrease during mizoribine monotherapy, all patients showed dramatic P/C decreases over the course of combination therapy. At 3, 6, and 12 months after combination therapy, 15%, 31%, and 62% of patients attained complete remission, respectively, and all patients were in partial or complete remission 6 months after combination therapy. No notable side effects were observed.

CONCLUSION: The addition of prednisone after mizoribine monotherapy can be beneficial for all IMN patients with nephrotic-range proteinuria syndrome. The risks associated with immunotherapy can be decreased by initially prescribing mizoribine alone, which might act as a base for establishing therapy, followed by low-dose prednisone treatment.