Rituximab treatment for difficult-to-treat nephrotic syndrome in children: a multicenter, retrospective study.

Background/aim This study aimed to evaluate the efficacy of rituximab in children with difficult-to-treat nephrotic syndrome, considering the type of disease (steroid-sensitive or ?resistant) and the dosing regimen. Materials and methods This multicenter retrospective study enrolled children with difficult-to-treat nephrotic syndrome on rituximab treatment from 13 centers. The patients were classified based on the steroid response and initial dose of rituximab as low (single dose of 375 mg/m2) or high (2-4 doses of 375 mg/m2). Clinical outcomes were compared. Results Data from 42 children [20 steroid-sensitive (frequent relapsing / steroid-dependent) and 22 steroid-resistant nephrotic syndrome, aged 1.9-17.3 years] were analyzed. Eleven patients with steroid-sensitive nephrotic syndrome (55%) had a relapse following initial rituximab therapy, with the mean time to first relapse of 8.4±5.2 months. Complete remission was achieved in 41% and 36% of steroid-resistant patients, with the median remission time of 3.65 months. At Year 2, eight patients in steroid-sensitive group (40%) and four in steroid-resistant group (18%) were drug-free. Total cumulative doses of rituximab were higher in steroid-resistant group (p=001). Relapse rates and time to first relapse in steroid-sensitive group or remission rates in steroid-resistant group did not differ between the low and high initial dose groups. Conclusions The current study reveals that rituximab therapy may provide a lower relapse rate and prolonged relapse-free survival in the steroid-sensitive group, increased remission rates in the steroid-resistant group, and a significant number of drug-free patients in both groups. The optimal regimen for initial treatment and maintenance needs to be determined.