Successful Therapy with Obinutuzumab in a Toddler with Primary Multidrug-Resistant Nephrotic Syndrome.

BACKGROUND/OBJECTIVES: Primary steroid-resistant nephrotic syndrome (SRNS) in children is an ominous diagnosis due to limited therapeutic options and poor prognosis. The younger the child, the greater the probability of a genetic etiology which is typically resistant to immunosuppressive therapy. International guidelines recommend genetic testing and a search for rare infectious causes in the youngest age group. When no identifiable etiology is found, an immunologic cause of SRNS is suspected, with few therapeutic options available, which lately have included anti-CD20 therapy for children > 7 years of age. This is the first report on the successful use of obinutuzumab in a very young child with primary SRNS. METHODS: Two consecutive doses of obinutuzumab, a humanized anti-CD20 antibody (300 mg/m2 BSA), were administered two weeks apart to a 24-month-old boy with severe, complicated SRNS which had been refractory to cyclosporin A and rituximab and in whom previous genetic testing and a search for multiple infectious causes had been negative. RESULTS: Complete remission of severe nephrotic syndrome was achieved 2 months after the last infusion with, to date, sustained resolution of proteinuria and normal serum albumin levels without further use of IMS drugs and no severe adverse effects noted. CONCLUSIONS: Obinutuzumab may be a rescue option for severe, multidrug-resistant ISN, even in young children, when no other therapeutic options are available.