Positive effects of single-daily high-dose mizoribine therapy after cyclophosphamide in young children with steroid-dependent nephrotic syndrome

BackgroundMizoribine (MZR) therapy after cyclophosphamide (CPM) therapy may be an attractive option in patients with steroid-dependent nephrotic syndrome (SDNS) for the purpose of maintaining remission. This is because CPM is administered only once due to its severe side effects such as gonadal toxicity. However, the long-term prognosis after the treatment regimen remains unknown.MethodsWe retrospectively analyzed the clinical course (median follow-up, 5.9years) of 54 young children with SDNS (43 boys; age<10years) who had undergone 12-week CPM therapy. The patients were classified into two groups: group A, undergoing MZR therapy for >12months for maintaining remission after CPM therapy (N=36), and group B, undergoing CPM monotherapy (N=18).ResultsFor 2years after CPM therapy, 21 of the 36 group A patients were in sustained remission, whereas only 4 of the 18 group B patients had maintained remission (58% vs. 22%, p<0.05). Furthermore, the rate of regression to SDNS after CPM was significantly lower in group A than in group B (6% vs. 39%, p<0.05). At the last follow-up (mean age, 10.9years), 27 of the 36 group A patients (75%) had not received any steroid-sparing agent after the treatment regimen.ConclusionsSingle daily high-dose MZR therapy after CPM therapy may have positive outcomes in young children with SDNS in the long term.