Kidney Week

Abstract: FR-PO0943

Rituximab-Induced Long-Term Remission in Childhood-Onset, Uncomplicated, Frequently Relapsing or Steroid-Dependent Nephrotic Syndrome: A Follow-Up Study of a Randomized, Placebo-Controlled Trial

Session Information

• Pediatric Nephrology: Genetic Diseases, Development, Neonatal Nephrology, Glomerular Diseases, and More
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

• 1800 Pediatric Nephrology

Authors

• Kimura, Yuka, Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan

Yuka Kimura, MD

• Horinouchi, Tomoko, Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan

Tomoko Horinouchi, MD, PhD

• Sako, Mayumi, Department of Clinical Research Promotion, Clinical Research Center, National Center for Child Health and Development, Tokyo, Japan

Mayumi Sako, MD, PhD

• Omori, Takashi, Graduate school of Health Data Science, Juntendo University, Urayasu, Chiba, Japan

Takashi Omori, PhD

• Sakai, Tomoyuki, Department of Pediatrics, Shiga University of Medical Science, Otsu, Shiga, Japan

Tomoyuki Sakai

• Yamamura, Tomohiko, Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan

Tomohiko Yamamura, MD, PhD

• Hamada, Riku, Tokyo Metropolitan Children’s Medical Center, Fuchu, Tokyo, Japan

Riku Hamada, MD

• Tanaka, Seiji, Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume, Fukuoka, Japan

Seiji Tanaka, MD, PhD

• Oka, Masafumi, Department of Pediatrics, Faculty of Medicine, Saga University, Saga city, Saga, Japan

Masafumi Oka, MD, PhD

• Kamei, Koichi, Division of Nephrology and Rheumatology, National Center for Child Health and Development, Tokyo, Japan

Koichi Kamei, MD, PhD

• Nozu, Kandai, Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan

Kandai Nozu, MD, PhD

• Iijima, Kazumoto, Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan

Kazumoto Iijima, MD, PhD

Group or Team Name

• Japanese Study Group of Kidney Disease in Children

Background

In a multicenter, double-blind, randomized, placebo-controlled trial (jRCT1091220380) we conducted, rituximab, administered at 375 mg/m² up to a maximum dose of 500 mg once weekly for 2 weeks, maintains remission in patients with childhood-onset uncomplicated frequently relapsing/steroid-dependent nephrotic syndrome (FRNS/SDNS) who had no prior exposure to steroid-sparing agents. Since the participants followed up for only 1-year trial period, assessment of long-term efficacy of rituximab remains a major clinical challenge.

Methods

We conducted a follow-up study using data up to December 2022 and 2024 to evaluate the long-term effects of rituximab after B-cell reconstitution (jRCT1050230024). In the original trial, 18 patients in the rituximab group and 22 in the placebo group were enrolled, and, as a rescue program, 19 patients in the placebo group who experienced early relapse were treated with open-label rituximab. Retrospective data included relapse dates, additional immunosuppressive therapy, safety outcomes, and were combined with the trial data. The primary endpoint was relapse-free survival from rituximab administration.

Results

37 rituximab-exposed patients were included in the extended follow-up analysis. Patients were followed without long-term steroids, immunosuppressants, or additional rituximab for relapse prevention until relapse occurred. The median observation period from rituximab administration was 1705 days. During follow-up, 25 of 37 patients experienced relapse. The Kaplan–Meier estimated relapse-free survival rate as of December 2024 was 29.7%. The median relapse-free period from rituximab administration was 260 days. All 12 relapse-free patients in 2022 remained relapse-free through 2024 without additional immunosuppressive therapy. During follow-up, hypogammaglobulinemia, defined as serum IgG < 700 mg/dL, occurred in 7 patients (18.9%), including severe cases, defined as serum IgG < 400 mg/dL, in 2 patients (5.1%).

Conclusion

The result suggests that rituximab enables the continuation of effective treatment beyond 1 year and well tolerated in patients with childhood-onset non-refractory FRNS/SDNS. These findings suggest that rituximab may induce a high rate of sustained long-term remission even after B-cell reconstitution in this patient population.