Renalys Pharma Announces Positive Phase 3 Results for Sparsentan in Japanese Patients with IgA Nephropathy
TOKYO, Nov. 26, 2025 /PRNewswire/ — Renalys Pharma, Inc. (Headquarters: chuo-ku, Tokyo; “Renalys”) today announced positive topline results from its Phase III clinical study of sparsentan (advancement code: RE-021), an orally administered dual endothelin and angiotensin II receptor antagonist (DEARA), in Japanese patients with IgA nephropathy (IgAN). Based on these results, the company plans to submit a New Drug Application in Japan in 2026.
The primary endpoint of the study assessed the percent change from baseline in the 24-hour urine protein-to-creatinine ratio (UPCR) after 36 weeks of oral administration of sparsentan in Japanese IgAN patients (N=35).The least-squares geometric meen percent change (95% CI) was -58.54% (-68.75%, -45.00%), confirming the efficacy of sparsentan in this patient population. Sparsentan was well-tolerated in the study with a safety profile consistent with other global trials and no new safety risks specific to Japanese patients were observed.
BT Slingsby, Chairman, CEO, and Co-Founder of Renalys, commented:
“In Japan, treatment options for IgAN remain limited, and unmet medical needs are extremely high.Sparsentan has already been approved in the United States and Europe, and from the viewpoint of addressing the drug lag, it is indeed imperative that we deliver this therapy to Japanese patients who need it as soon as possible.”
Ryutaro Shimazaki, Chief Development Officer of Renalys, commented:
“This Phase III study in Japan was able to be conducted as a small-scale bridging study following extensive discussions with the PMDA, enabling the use of data from large-scale overseas clinical trials.the study included both adult and pediatric patients aged 10 years and older, and strong reductions in proteinuria consistent with international trial results were observed across all age groups. We extend our deepest gratitude to the patients, investigators, and all those involved in conducting this study.”
Naoki kashihara, MD, PhD, President of Japan Kidney Association, commented:
“For rare kidney diseases such as IgAN, progress in developing effective therapies had long been limited. It is indeed encouraging to see accelerated drug development in this field. Sparsentan has demonstrated strong proteinuria-lowering effects and a favorable safety profile,as shown in both large global clinical trials and this clinical study in japanese patients. Furthermore, sparsentan is expected to have potential not only for rare kidney diseases such as FSGS and Alport syndrome but also more broadly for chronic kidney disease (CKD), which is one of the unique advantages of this therapy.Prior to this clinical study in Japanese patients,the Japanese Society of Nephrology used its large patient database to clarify the relationship…
Renalys Pharma Announces Positive Results with Angiotensin II Receptor Antagonist for IgA Nephropathy
Tokyo,Japan – November 26,2025 – renalys Pharma,Inc., a late-stage clinical biopharmaceutical company focused on renal disease, today announced promising results with an angiotensin II receptor antagonist (ARA) in slowing kidney function decline in adults with primary immunoglobulin A nephropathy (IgAN) at risk of disease progression. The company is developing this therapy to address a significant unmet need in Japan, where IgAN is a leading cause of kidney failure.
Understanding IgA Nephropathy
IgA nephropathy is a chronic kidney disease characterized by the deposition of abnormal IgA proteins in kidney tissue, leading to inflammation and impaired kidney function. It is designated as a rare intractable disease in Japan (designated as intractable disease 66). The disease’s underlying causes and varying severity remain poorly understood, contributing to the lack of approved treatments currently available in the country.Chronic kidney disease (CKD) and end-stage renal disease (ESRD) pose a considerable burden on the Japanese healthcare system, making new therapeutic options for IgAN critically crucial.A recent study highlighted the potential of proteinuria reduction as a surrogate endpoint in clinical trials for IgAN in Japanese patients (Kashihara, 2025).
Renalys Pharma’s Commitment
Renalys Pharma, founded by Catalys Pacific and SR One, is dedicated to developing innovative treatments for renal diseases specifically tailored to Japanese and Asian patients. The company aims to combat the “drug loss” experienced in the region by accelerating access to novel therapies.
“We are committed to addressing the growing needs of patients suffering from renal diseases,” said BT Slingsby, MD, PhD, MPH, representative of Renalys Pharma, Inc. “Our work with this ARA represents a significant step forward in providing a much-needed treatment option for individuals with IgAN.”
Upcoming Transition to Chugai Pharmaceutical
Renalys Pharma is scheduled to become a wholly owned subsidiary of Chugai Pharmaceutical Co., Ltd. on November 27, 2025.This integration is expected to further strengthen the development and commercialization of Renalys Pharma’s pipeline, including the ARA for IgAN. Details regarding the merger can be found in the official press release: https://www.chugai-pharm.co.jp/news/detail/20251118173000_1531.html.
About Renalys Pharma, Inc.
Renalys Pharma, Inc. is a privately held,late-stage clinical biopharmaceutical company based in Japan.
* Address: 3-11, Nihonbashi-honcho 2-chome, Chuo-ku, Tokyo, Japan
* Representative: BT Slingsby, MD, PhD, MPH
* Website: (URL not provided in source material)
Disclaimer: This facts is for disclosure of management information and is not intended as advertising or medical advice.
Reference:
- Kashihara, N. (2025). Proteinuria reduction as a surrogate endpoint for clinical study of IgA nephropathy in Japanese patients: data from the J-CKD-DB-Ex. Clin Exp Nephrol. doi: 10.1007/s10157-025-02788-4.
SOURCE: Renalys Pharma, Inc.