Renalys Pharma, Inc., a privately held late-stage biopharmaceutical company, and Chugai Pharmaceutical Co., Ltd., a research-based pharmaceutical company, have entered into a definitive stock purchase agreement under which Chugai will acquire Renalys.
As part of the transaction, Chugai will gain exclusive rights to develop and commercialize sparsentan in Japan, South Korea, and Taiwan. Sparsentan, initially developed by Travere Therapeutics, Inc., is approved in the United States and Europe for the treatment of IgA nephropathy (IgAN).
Through the acquisition, Chugai will assume Renalys’s late-stage development programs for sparsentan in IgA nephropathy, focal segmental glomerulosclerosis (FSGS), and Alport syndrome.
Renalys was established to address Asia’s persistent “drug lag” by accelerating access to innovative therapies for chronic kidney disease (CKD). The company has completed primary endpoint data collection in its Phase III Japanese clinical trial of sparsentan for IgA nephropathy, with topline results expected in Q4 2025.
Renalys has also reached regulatory alignment with the Pharmaceuticals and Medical Devices Agency (PMDA) on registrational trial plans for FSGS and Alport syndrome.
Dr. BT Slingsby, CEO and co-founder of Renalys, said:
“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 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 practical steps that get sparsentan to patients sooner.”
Sparsentan is an oral dual endothelin and angiotensin II receptor antagonist developed by Travere Therapeutics, Inc. and marketed in the U.S. as Filspari.
Japan faces a growing burden from chronic kidney disease (CKD) and end-stage renal disease (ESRD), both recognized as major public health and social challenges.
A leading cause of kidney failure, IgAN occurs when abnormal IgA proteins deposit in the kidneys, triggering inflammation. It is designated as intractable disease No. 66 in Japan, with no approved therapies currently available.
FSGS is an important cause of kidney failure, characterized by scarring of glomeruli and progressive loss of renal filtration function. It is classified as designated intractable disease No. 222, with limited treatment options and steroid-resistant cases posing ongoing challenges.
A hereditary kidney disorder caused by mutations in type IV collagen genes, Alport syndrome leads to renal impairment, hematuria, and proteinuria beginning in childhood. Severe cases often progress to ESRD in adolescence or early adulthood. It is classified as designated intractable disease No. 218 and currently lacks curative treatment.
Renalys Pharma, Inc. is a privately held late-stage clinical biopharmaceutical company based in Japan. The company focuses on developing innovative therapeutics for chronic kidney diseases and other renal conditions affecting Japanese and Asian patients.
Chugai Pharmaceutical Co., Ltd., headquartered in Tokyo, Japan, is a research-based pharmaceutical company recognized for its world-class antibody engineering technologies. The company is committed to developing innovative therapies that address unmet medical needs and improve patient outcomes globally.
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