Kidney Week

Abstract: FR-OR066

Proteinuria-Reducing Effect of Sparsentan in Japanese Pediatric and Adult Patients with IgAN: Interim Analysis at Week 36

Session Information

• New IgAN Therapies: Subgroups, Outcomes, and Biomarkers
  October 23, 2026 | Location: Room 501, Convention Center
  Abstract Time: 04:50 PM - 05:00 PM

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Suzuki, Yusuke, Juntendo University Faculty of Medicine, Tokyo, Japan

Yusuke Suzuki, MD, PhD

• Suzuki, Hitoshi, Juntendo University Urayasu Hospital, Chiba, Japan

Hitoshi Suzuki, MD, PhD

• Nakanishi, Koichi, University of the Ryukyus, Okinawa, Japan

Koichi Nakanishi, MD, PhD

• Hayashi, Terumasa, Osaka General Medical Center, Osaka, Japan

Terumasa Hayashi, MD, PhD

• Akizawa, Tadao, Showa Medical University, Tokyo, Japan

Tadao Akizawa, MD

• Watanabe, Yuzo, Kasugai Municipal Hospital, Aichi, Japan

Yuzo Watanabe, MD

• Shimazaki, Ryutaro, Renalys Pharma, Inc., Tokyo, Japan

Ryutaro Shimazaki, RD

• Slingsby, Bt, Renalys Pharma, Inc., Tokyo, Japan

Bt Slingsby

• Sato, Takakazu, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan

Takakazu Sato

• Matsushima, Junnosuke, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan

Junnosuke Matsushima

• Kashihara, Naoki, Kawasaki Medical School, Okayama, Japan

Naoki Kashihara, MD, PhD

Background

Sparsentan is a novel dual endothelin–angiotensin receptor antagonist approved in the US and EU for primary IgA nephropathy (IgAN), based on the results of the global phase 3 PROTECT study.

Methods

This ongoing phase 3 (jRCT2051240070), multicenter, open label, single arm study evaluates the efficacy and safety of sparsentan in Japanese patients (Pts) with IgAN. Pts were initiated on 200 mg sparsentan once daily for 2 wks, followed by a 400-mg maintenance dose up to 110 wks. The key inclusion criteria were primary IgAN diagnosed by kidney biopsy, age ≥10 y, receiving renin angiotensin system inhibitors for ≥12 wks, urine protein ≥0.5 g/day, and eGFR ≥30 mL/min/1.73 m². The primary endpoint was % change from baseline in 24-h urine protein/creatinine ratio (UPCR) at wk 36 (interim analysis). Secondary endpoints for the interim analysis were change from baseline in eGFR and a composite of kidney failure (confirmed 40% eGFR reduction, end-stage kidney disease, or all cause mortality).

Results

In total, 35 Pts were enrolled (mean±SD age, 44.8±18.1 y; females, 60%; UPCR, 1.16±0.74 g/g; urine protein, 1.31±1.13 g/day; eGFR, 57.9±25.6 mL/min/1.73 m²). Pediatric Pts (<18 y at baseline) accounted for 17.1% of the population, with a median (range) age of 14.5 (11–17) y. The geometric least squares mean (95% CI) % change from baseline in UPCR at wk 36 was −58.54% (−68.75, −45.00) (Fig). Overall, 45.7% of Pts achieved complete proteinuria remission (<0.3 g/day) by wk 36. The mean eGFR was maintained over 36 wks (57.0±22.9 mL/min/1.73 m² at wk 36), with no events of the composite kidney failure endpoint. Subgroup analyses showed reductions in proteinuria from baseline in all subgroups, with consistent reductions in pediatric and adult Pts. All AEs were mild to moderate, with no safety concerns specific to Japanese Pts.

Conclusion

Sparsentan reduced proteinuria, preserved kidney function, and was well tolerated in both pediatric and adult Japanese Pts over 36 wks, consistent with the results of the PROTECT study.

Percent change from baseline in UPCR using MMRM analysis with imputation (FAS)

Funding

• Commercial Support – CHUGAI PHARMACEUTICAL CO., LTD.