Late-onset adverse events after a single dose of rituximab in children with complicated steroid-dependent nephrotic syndrome

Background: Rituximab (RTX) is regarded as a relatively safe and effective treatment for children with steroid-dependent nephrotic syndrome (SDNS). However, late-onset adverse events after RTX, including neutropenia, hypogammaglobulinemia, and increased risk of infections, have been rarely reported in this cohort. Materials and methods: This was a single-center retrospective analysis of adverse events during B-cell depletion periods after a single dose of RTX (375 mg/m(2)) in 60 patients with complicated SDNS (total 126 doses). After RTX, maintenance therapy with cyclosporine (CsA) or mycophenolate mofetil (MMF) was continued, and prednisolone was discontinued within 6 months. To detect potential drug toxicity, clinical and laboratory parameters were measured before and 1 week after RTX infusion and every month thereafter during B-cell depletion periods (at least 6 months). A single dose of RTX was added if NS relapsed despite maintenance therapy with MMF or CsA after the re-emergence of CD19+ B cells (> 1% of total lymphocytes) in the peripheral blood. Results: Severe neutropenia (neutrophil count < 500/mm(3)) was identified in 3 patients and hypogammaglobulinemia (IgG levels < 500 mg/dL) in 9 patients. During B-cell depletion periods (median 5 months; range 1 - 20 months), 2 patients required hospitalization because of bacterial infections. However, no life-threatening infections were identified in our cohort. Conclusion: Although neutropenia and hypogammaglobulinemia should be kept in mind as late-onset adverse events of RTX therapy in patients with complicated SDNS, severe infections during B-cell depletion periods are infrequent when our treatment strategies are implemented.