Efficacy and safety of long-term repeated use of rituximab in pediatric patients with nephrotic syndrome

We aimed to investigate the efficacy and safety of repeated use of rituximab (RTX) in pediatric patients with nephrotic syndrome (NS). Retrospective review of 50 patients with steroid-dependent NS (SDNS) who had received more than three cycles of RTX was conducted; each consisted of one to four infusions until B lymphocytes were depleted. The median age of starting the first RTX cycle was 12.4 years (interquartile ranges (IQR) 10.2–14.6). During a median follow-up period of 6.3 (IQR 3.6–8.6) years, patients received a median of 5.0 RTX cycles (IQR 4.0–7.3). The number of relapses decreased from a median of 2.0 relapses per year (IQR 1.0–3.0) to 0.2 relapses per year (IQR 0.0–0.5) after long-term RTX treatments (P < 0.001). Longer relapse-free periods were associated with more than four RTX cycles, longer B-cell depletion, older age at each RTX treatment, and lower cholesterol levels. B lymphocytes recovered to 1% at a median of 5.9 months (95% confidence interval 5.7–6.1) after RTX administration. Factors related to a longer period of B-cell depletion included more than five RTX cycles, a higher dose of RTX, older age at treatment, and concurrent use of antimetabolites. During repeated RTX treatments, 8.0%, 6.0%, and 2.0% of patients developed hypogammaglobulinemia, severe infection, and severe neutropenia, respectively. Long-term repeated use of RTX may be effective and safe in pediatric NS patients. Furthermore, the redosing of RTX could be chosen by considering predictive factors for relapse-free and B-cell depletion periods.