Study of the efficacy of mizoribine in lupus nephritis in Chinese patients.

We conducted a clinical study in China on the efficacy and safety of mizoribine (MZR) in lupus nephritis. Eleven subjects with proteinuria (≥2 g/day) who had undergone renal biopsy confirming a diagnosis of lupus nephritis (class III: 1 subject; class IV: 6 subjects; class V: 4 subjects) were enrolled. Nine of the subjects were treatment- naive patients who received remission induction therapy, and the other two were switched from cyclophosphamide (CTX) or mycophenolate mofetil due to lack of efficacy. MZR 150 mg was administered once a day. After 6 months, the remission rate was 72.7% (2 subjects achieved complete remission, and 9 partial remission). After 3 and 6 months, significant reductions (p < 0.01) were obtained in 24-h proteinuria (g/day). In the subjects switched to MZR due to lack of efficacy with CTX, the dose was increased from MZR 150-200 mg due to inadequate improvement in proteinuria, and this dose escalation resulted in complete remission after 6 months. It is believed that this kind of dose escalation is one possible treatment option for lupus nephritis. In this study, no adverse events occurred in any of the subjects. We therefore concluded that this first use in China as remission induction therapy in lupus nephritis patients of MZR, which is recognized as an effective maintenance therapy in Japan, was effective. The results also suggest that MZR could be effective in patients for whom other drugs have been insufficiently effective.