Renalys Completes Data Collection for Sparsentan Phase III Trial in Japan

Renalys Pharma's Milestone in Kidney Treatment

On October 10, 2025, Renalys Pharma, Inc., headquartered in Chuo-ku, Tokyo, made a significant announcement regarding its Phase III clinical trial for Sparsentan, a promising treatment aimed at addressing IgA nephropathy. The company revealed that it has successfully completed data collection for the primary endpoint of the trial in Japan. This marks a pivotal step forward in the evaluation of Sparsentan’s efficacy and safety in treating patients suffering from this chronic kidney disease.

The primary endpoint assessed during the trial involved measuring the urine protein creatinine ratio via a 24-hour urine collection at the 36-week milestone. With the data collection phase now complete, Renalys is poised to move forward to analyze the gathered data, focusing on the efficacy and safety of Sparsentan over the 36-week treatment period. The results from this trial will also be compared with data from global Phase III trials as part of Renalys' preparations for a New Drug Application (NDA) submission.

Renalys Pharma is dedicated to combating kidney disease in Japan and other regions in Asia by developing innovative therapeutic solutions. Sparsentan, which is an oral dual endothelin and angiotensin II receptor antagonist, was initially developed by Travere Therapeutics, Inc. Renalys holds the exclusive rights to develop and commercialize Sparsentan within Japan and multiple Asian markets.

The significance of Sparsentan was highlighted in 2024 when it received full FDA approval under the brand name FILSPARI® to slow down kidney function decline in adults diagnosed with primary IgA nephropathy who are at risk for disease progression. This approval was based on the positive outcomes reported from the PROTECT Study, which illustrated that FILSPARI notably reduced proteinuria and helped in preserving kidney function compared to irbesartan, another medication typically used for similar purposes. The PROTECT trial is acknowledged as the sole study comparing IgA nephropathy treatments against an active comparator, further enhancing confidence in the medication's efficacy and safety profile.

Continuing its momentum, in 2025, Travere's supplemental new drug application (sNDA) for FILSPARI was accepted by the FDA for treating focal segmental glomerulosclerosis (FSGS), while European markets also welcomed FILSPARI with approved indications for IgA nephropathy by the end of 2025.

Understanding IgA Nephropathy

IgA nephropathy is a pressing healthcare concern that burdens the Japanese medical system, being one of the predominant causes of kidney failure. This condition is characterized by the accumulation of abnormal IgA proteins in kidney tissues, which hinder optimal kidney function and provoke inflammation. Despite its prevalence, treatment options remain limited, and IgA nephropathy is classified as a rare intractable disease, presenting various challenges regarding understanding its onset and severity.

In light of this situation, Renalys Pharma aims to fill the existing treatment gap by bringing innovative therapies like Sparsentan to market with urgency and dedication. The company's commitment reflects its foundational goal: to improve the quality of life for patients with kidney diseases across Japan and other territories in Asia.

About Renalys Pharma, Inc.

Founded in 2023 by Catalys Pacific and SR One, Renalys Pharma is a late-stage clinical biopharmaceutical firm focused on addressing unmet medical needs relating to renal health. With the increasing incidence of "drug loss" in renal disease management, Renalys is determined to enhance access to groundbreaking therapies that can offer real solutions for patients grappling with these serious health conditions. Currently led by BT Slingsby, MD, PhD, MPH, the company operates from its Tokyo headquarters, further emphasizing its strong commitment to fostering innovative healthcare advancements in the region. Visit Renalys' Website for more information on their progress and initiatives in kidney health.