Chugai Pharmaceutical has agreed to acquire Renalys Pharma, a Tokyo-based biotechnology company focused on advancing treatments for chronic kidney disease. The acquisition, which grants Chugai exclusive rights to develop and commercialize the kidney drug sparsentan in Japan, South Korea, and Taiwan, represents a major step forward in expanding access to innovative renal therapies across Asia.
Renalys, founded with the mission to close Asia’s persistent “drug lag,” has been advancing sparsentan for IgA nephropathy (IgAN)—a serious chronic kidney disease that often leads to end-stage renal failure.
The drug, originally developed by Travere Therapeutics, is already approved in the United States and Europe. Renalys recently completed data collection for its Japan Phase III trial evaluating sparsentan in IgAN, with topline results expected in the fourth quarter of 2025.
In addition to its IgAN program, Renalys has reached agreements with Japan’s Pharmaceuticals and Medical Devices Agency (PMDA) to pursue registrational trials for focal segmental glomerulosclerosis (FSGS) and Alport syndrome, two other rare renal conditions lacking effective treatment options.
Under the acquisition terms, Chugai will pay ¥15 billion (approximately USD 100 million) in cash upon closing, subject to standard purchase price adjustments. Additional earn-out payments of up to ¥16 billion will be tied to regulatory and commercial milestones across the three territories.
For Chugai, the transaction reinforces its position as a leader in rare disease and nephrology innovation, complementing its existing drug portfolio and pipeline. The deal also ensures that patients across the region gain faster access to a therapy that has already shown promise globally.
Renalys leadership emphasized that Chugai’s infrastructure, scale, and clinical expertise make it the ideal partner to accelerate sparsentan’s delivery to patients. The company views the transaction as both a validation of its regional development model and a catalyst for expanding access to advanced kidney care.
KEY QUOTES:
“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.”
BT Slingsby, MD, PhD, MPH, Representative Director, Chairman & CEO, and Co-Founder, Renalys Pharma, Inc.
“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.”
Ryutaro Shimazaki, Chief Development Officer, Renalys Pharma, Inc.
