Chugai Pharmaceutical has entered into a definitive stock purchase agreement to acquire Renalys Pharma, a company focused on advancing innovative therapies for chronic kidney disease across Asia.

Renalys is currently developing sparsentan in Japan — a medicine initially developed by Travere Therapeutics and already approved in the United States and Europe for the treatment of IgA nephropathy. Under the agreement, Chugai will gain exclusive rights to develop and commercialise sparsentan in Japan, South Korea, and Taiwan.

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. It has also reached agreements with Japan’s Pharmaceuticals and Medical Devices Agency (PMDA) on registrational trial plans for focal segmental glomerulosclerosis (FSGS) and Alport syndrome.  

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

BT Slingsby, Representative Director, Chairman & 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 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."

Under the terms of the agreement, Chugai will pay JPY 15.0 billion (USD 97.5 million) in cash upon completion of the share acquisition, subject to customary purchase price adjustments. Additionally, Renalys may receive up to JPY 16.0 billion (USD 104 million) in milestone payments based on regulatory achievements and net sales performance of sparsentan in Japan, South Korea, and Taiwan.