By Fineline Cube 
Chugai Pharmaceutical, a member of the Roche Group, announced on October 24, 2025, that it will acquire all shares of Tokyo-based Renalys Pharma, making it a wholly-owned subsidiary. This strategic move secures exclusive rights for sparsentan in Japan, South Korea, and Taiwan.
Renalys Pharma Background
Renalys Pharma, established in April 2023 with funding from Catalys Pacific and SR One, holds exclusive development and commercialization rights for sparsentan in Japan, South Korea, and Taiwan. Sparsentan, an oral small-molecule drug for IgA nephropathy (IgAN), was launched in the US as FILSPARI in February 2023 and approved in Europe in April 2024. It is currently undergoing a Phase III clinical trial in Japan.
Transaction Details
The total transaction consideration could reach up to JPY 31 billion (over USD 200 million). Chugai will pay an upfront cash payment of JPY 15 billion (approximately USD 98 million) upon closing. Additional payments of up to JPY 16 billion in milestones and sales royalties are contingent on sparsentan’s regulatory approval and sales performance in the three markets.
Strategic Fit
Sparsentan is expected to complement Chugai’s own IgA nephropathy nucleic acid drug, sefaxersen (development code: RG6299), which is currently in development.-Fineline Info & Tech