Study protocol: mycophenolate mofetil as maintenance therapy after rituximab treatment for childhood-onset complicated frequently-relapsing nephrotic syndrome or steroid-dependent nephrotic syndrome: a multicenter double-blind randomized placebo-controlled trial (JSKDC07)

摘要

BackgroundIdiopathic nephrotic syndrome (INS) is the most common chronic glomerular disease in children. Approximately 80–90% of patients with childhood INS have steroid-sensitive nephrotic syndrome (SSNS), and can obtain remission with steroid therapy, while the remainder have steroid-resistant nephrotic syndrome (SRNS). Furthermore, approximately 50% of children with SSNS develop frequently-relapsing nephrotic syndrome (FRNS) or steroid-dependent nephrotic syndrome (SDNS). Children with FRNS/SDNS are usually treated with immunosuppressive agents such as cyclosporine, cyclophosphamide, or mizoribine in Japan. However, 10–20% of children receiving immunosuppressive agents still show frequent relapse and/or steroid dependence during or after treatment, which is defined as complicated FRNS/SDNS. Furthermore, 30% of SRNS patients who obtain remission after additional treatments such as cyclosporine also turn out to be complicated FRNS/SDNS. For such complicated FRNS/SDNS patients, rituximab (RTX) is currently used; however, recurrence after RTX treatment also remains an open issue. Because long-term use of existing immunosuppressive drugs has limitations, development of a novel treatment for maintenance therapy after RTX is desirable. Mycophenolate mofetil (MMF) is an immunosuppressive drug with fewer side effects than cyclosporine or cyclophosphamide. Importantly, recent studies have reported the efficacy of MMF in children with nephrotic syndrome.