R1 Therapeutics, a California-based biotech, raised an oversubscribed $77.5 million Series A funding round on March 17-18, 2026, co-led by Abingworth, F-Prime Capital, and DaVita Venture Group, with participation from Curie.Bio, SymBiosis, and U.S. Renal Care.123
The funds will advance AP306, a first-in-class pan phosphate transporter inhibitor that blocks active phosphate transport in the gut for treating hyperphosphatemia in chronic kidney disease patients on dialysis.124
AP306 was licensed exclusively worldwide (outside Greater China) from Alebund Pharmaceuticals, which completed Phase 2a trials in China showing significant serum phosphate reduction; a global Phase 2b study is planned for later 2026.135
CEO Krishna Polu highlighted AP306's potential for superior efficacy and lower pill burden compared to existing phosphate binders.124
The raise was part of a busy fundraising day including Mestag Therapeutics and iDEL Therapeutics for cancer programs.17
Sources:
1. https://www.biospace.com/business/r1-leads-busy-fundraising-day-with-77-5m-series-a-raise-for-kidney-disease
2. https://www.fiercebiotech.com/biotech/r1-zooms-out-stealth-775m-series-financing-advance-chronic-kidney-disease-treatment
3. https://www.startupresearcher.com/news/r1-therapeutics-launches-with-usd77-5-million-series-a-to-tackle-kidney-disease
4. https://www.bioxconomy.com/investment/r1-therapeutics-debuts-with-77-5m-to-tackle-kidney-disease
5. https://www.fiercebiotech.com/biotech/fierce-biotech-fundraising-tracker-26