Renalys Pharma to be Acquired by Chugai Pharmaceutical

TOKYO, Oct. 24, 2025  /PRNewswire/ -- Renalys Pharma, Inc. (Headquarters: Tokyo; Representative Director Chaiman & CEO; BT Slingsby; "Renalys") and Chugai Pharmaceutical Co., Ltd. (Headquarters: Tokyo; President & CEO: Osamu Okuda; "Chugai") today announced a definitive stock purchase agreement, under which Chugai will acquire Renalys (the "Transaction").  Renalys is advancing sparsentan in Japan; the medicine was initially developed by Travere Therapeutics, Inc. ("Travere") and is approved in the United States and Europe for the treatment of IgA nephropathy. As part of the Transaction, Chugai will gain exclusive rights to develop and commercialize sparsentan in Japan, South Korea, and Taiwan.

Founded to close Asia's persistent "drug lag," Renalys develops innovative therapies for chronic kidney disease across Japan and the region. The company has completed primary endpoint data collection in its Japan Phase III clinical trial of sparsentan for IgA nephropathy, with topline results expected in Q4 2025. Renalys has also reached agreements with the Pharmaceuticals and Medical Devices Agency (PMDA) on registrational trial plans for focal segmental glomerulosclerosis (FSGS) and Alport syndrome in Japan.

Renalys believes that transferring sparsentan to Chugai, a company recognized for its rare-disease and nephrology expertise, will accelerate access for patients across Asia.

BT Slingsby, MD, PhD, MPH, Representative Director, Chairman & CEO, and Co-Founder of Renalys, stated: "Renalys was built to close Asia's drug lag with a simple promise: patients should not have to wait years for proven therapies. By advancing sparsentan in Japan, we proved that the model works. Partnering with Chugai now scales it—accelerating access across Japan and the region and setting a new standard for how innovative renal medicines reach patients."

Ryutaro Shimazaki, Chief Development Officer of Renalys, added:

"Chugai brings scale, speed, and deep know-how in renal disease. Together, we will align development with PMDA expectations, prepare clinicians for adoption, and focus on the practical steps that get sparsentan to patients sooner. Our goal is simple and urgent: convert strong data into real access for people living with IgA nephropathy, FSGS, and Alport syndrome."

Financial Terms

Upfront payment: Upon execution of the Share Acquisition, Chugai will pay Renalys JPY 15.0 billion in cash, subject to customary purchase-price adjustments.

Earn-outs: Chugai will pay up to JPY 16.0 billion in cash tied to regulatory milestone achievements for sparsentan and to net sales in Japan, South Korea, and Taiwan. 

About sparsentan

Sparsentan is an oral dual endothelin and angiotensin II receptor antagonist developed by Travere Therapeutics, Inc. ("Travere").  Renalys has an exclusive license for development and commercialization of sparsentan in Japan and several Asian territories. In Japan, data collection for the primary endpoint has been completed for all evaluable patients in the Phase III clinical trial of IgA nephropathy, with topline results expected in Q4 2025. In 2024, Travere received full FDA approval for sparsentan (U.S. brand name: FILSPARI®) to slow kidney function decline in adults with primary IgA nephropathy (IgAN) who are at risk of disease progression*. Full approval is based on positive long-term confirmatory results from the PROTECT Study demonstrating that FILSPARI® significantly slowed kidney function decline over two years compared to irbesartan. In the PROTECT Study, the only head-to-head study in IgA nephropathy versus an active comparator, FILSPARI® demonstrated a significant reduction in proteinuria, preservation of kidney function and a well-tolerated safety profile compared with active control irbesartan. In Europe, FILSPARI® received standard EU approval for the IgA nephropathy indication in 2025. In 2025, the FDA accepted for review Travere's supplemental new drug application (sNDA) for FILSPARI® for the treatment of focal segmental glomerulosclerosis (FSGS).

*FILSPARI® (sparsentan) U.S. Indication:

FILSPARI is an endothelin and angiotensin II receptor antagonist indicated to slow kidney function decline in adults with primary IgA nephropathy (IgAN) who are at risk of disease progression.

About IgA Nephropathy

The management of patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) has become a social issue that places a heavy burden on the Japanese healthcare system. IgA nephropathy is widely known as one of the main causes of kidney failure and is considered to develop when abnormal IgA proteins are deposited in kidney tissue, inhibiting kidney function and causing inflammation. IgA nephropathy is a rare intractable disease (designated as an intractable disease 66) with many unresolved mechanisms of onset and severity. Currently, there is significant unmet need for approved treatment for IgA nephropathy in Japan.

About Focal Segmental Glomerulosclerosis (FSGS)

Chronic kidney disease (CKD) and end-stage renal disease (ESRD) impose a significant burden on Japan's healthcare system and represent a major social issue. FSGS is recognized as an important cause of kidney failure, with many patients progressing to ESRD requiring dialysis. The disease is characterized by focal and segmental sclerosis of glomeruli, which impairs renal filtration function. FSGS is classified as one of the designated intractable nephrotic syndromes (designated intractable disease No. 222) in Japan. Because the precise mechanisms underlying disease onset and progression remain unclear and steroid-resistant cases exist, treatment can be challenging. Currently, therapeutic options for FSGS in Japan are limited, creating a significant unmet medical need.

About Alport Syndrome

Alport syndrome is a hereditary kidney disorder characterized by hematuria and proteinuria that begin in childhood and progressively lead to renal impairment. The disease results from mutations in genes encoding type IV collagen, causing structural defects in the glomerular basement membrane and consequent renal dysfunction.

Severe cases often progress to end-stage renal disease in male patients during late adolescence or early adulthood and may also present with hearing loss or ocular symptoms.  As a rare disease (designated intractable disease No. 218), Alport syndrome remains without an established curative treatment, and effective therapeutic options are urgently needed.

About Renalys Pharma, Inc.

Renalys Pharma, a privately held late-stage clinical biopharmaceutical company based in Japan, is committed to the development of innovative therapeutics targeting unmet needs in the management of renal disease for Japanese and Asian patients. Founded by Catalys Pacific and SR One, the company aims to address the growing "drug loss" in the region by catalyzing access to new treatments for kidney disease patients.

About Chugai Pharmaceutical, Co.

Chugai Pharmaceutical Co., Ltd., headquartered in Tokyo, is a research-based pharmaceutical company with world-class drug discovery capabilities, including proprietary antibody engineering technologies. Chugai is committed to creating innovative pharmaceutical products that may satisfy unmet medical needs. Chugai is listed on the Prime Market of the Tokyo Stock Exchange.  While maintaining autonomy and management independence, Chugai is an important member of the Roche Group. Additional information is available at https://www.chugai-pharm.co.jp/english/.

Company Name: Renalys Pharma, Inc.
Address: 3-11, Nihonbashi-honcho 2-chome, Chuo-ku, Tokyo, Japan
Representative: BT Slingsby, MD, PhD, MPH

URL: https://renalys.com/

[Disclaimer]

Information concerning pharmaceutical products (compound under development) contained herein is not intended as advertising or as medical advice, but intended for disclosure of management information.

SOURCE Renalys Pharma, Inc.