Efficacy and Safety of Obinutuzumab Versus Rituximab in Childhood Steroid Dependant and Frequent Relapsing Nephrotic Syndrome

B-cell depletion with rituximab induces sustained remission in children with Steroid-Dependent or Frequent Relapsing Nephrotic Syndrome (SD/FRNS). However, most patients relapse after B-cell recovery and some do not achieve B-cell depletion. Obinutuzumab is a 2nd generation humanized monoclonal antiCD20 antibody, with enhanced B cell-depleting potential. It has been reported safe and efficient in different renal autoimmune diseases including childhood nephrotic syndrome. This double-blind, randomized multicenter study is designed to assess the efficacy and safety of a single infusion of low-dose obinutuzumab compared to a single infusion of rituximab in children with frequently relapsing nephrotic syndrome (FRNS) or steroid-dependent nephrotic syndrome (SDNS).

Idiopathic nephrotic syndrome (INS) is the most frequent acquired glomerulopathy in children. The initial treatment relies on steroids, which enables remission of proteinuria in 90% of children. However, 80 % of steroid-sensitive patients will relapse, and 2/3 will become steroid-dependant with a long lasting disease over years. In this situation, immunosuppressive drugs are added as steroid-sparing agents. There is no international consensus on the second line treatment strategy after initial steroid therapy. RCT have demonstrated the efficacy of rituximab (RTX) to maintain remission in FR/SDNS after oral treatments withdrawal, however most patients relapse within 2 years, and some patients are resistant or allergic to Rituximab. Obinutuzumab (OBI) is a second generation antiCD20 mAb, that has been designed to overcome rituximab resistance in B-cell malignancies. Additional mechanisms of rituximab failure support the hypothesis that B-cell depletion could be optimized with OBI in autoimmune diseases. OBI has met its primary endpoint in lupus nephritis and a few randomized controlled trials are currently ongoing in nephrology for lupus nephritis and membranous nephropathy. We believe that a single infusion of OBI could reduce the risk of subsequent relapse in FR/SDNS and the cumulative exposure to immunosuppressive drugs.