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

Inclusion Criteria: * Age between 3 and 18 years * Steroid dependant Nephrotic Syndrome defined as: * 2 or more relapses during steroids or within 2 weeks following discontinuation. * 2 or more relapses including one under steroid-sparing agent (MMF, Calcineurin inhibitors, cyclophosphamide, levamisole) or within 6 months following treatment withdrawal OR Frequent Relapsing Nephrotic Syndrome defined as: * 2 or more relapses within 6 months following first remission * 3 or more relapses within any 12-month period * Last relapse within 3 months prior to inclusion * In remission, defined as 3 consecutive urinary dipsticks without proteinuria, at the time of randomization * Vaccination schedule in accordance with the current recommendations in France * Informed consent from parents Exclusion Criteria: * Secondary cause of nephrotic syndrome (such as membranous nephropathy, IgA nephropathy, lupus nephritis) * Primary or secondary steroid resistance nephrotic syndrome * Prior treatment with Rituximab within 6 months * Prior treatment with obinutuzumab at any time * CD20+ B-cell count \< 2.5% * Patient with neutrophils \< 1.5 G/L and/or platelets \< 75 G/L * GFR \< 80 ml/min/1.73m2 * Weight \<16kg * History of severe infection such as tuberculosis, hepatitis B, hepatitis C or HIV infection or LEMP * History of malignancy- Uncontrolled infection (viral, bacterial and fungal) * Vaccination with a live vaccine within 4 weeks prior to assignment/randomization * Known hyperprolinemia * Hypersensitivity to the active substance (OBI or RTX) or to proteins of murine origin, or to any of the other excipients * Pregnancy or breastfeeding or ability to become pregnant and refusal to use effective contraception during the 18 months following the study treatment (only 1 infusion of obinutuzumab/Rituximab at the beginning of the study) * Patient without medical insurance coverage (beneficiary or legal)