R1 Therapeutics Expands Financing for AP306 Phase 2b Trial
News related to:R1 Therapeutics · 2 min read
REDWOOD CITY, Calif., Sept. 30, 2026 /CourierPR/ -- R1 Therapeutics, a clinical-stage biopharmaceutical company focused on developing first-in-class therapies for patients with kidney disease, has expanded its Series A financing to $80.5 million, with new investment from Samsara BioCapital. This funding will support the continued development of R1’s lead asset, AP306, a first-in-class pan phosphate transporter inhibitor, as a monotherapy for hyperphosphatemia in patients with chronic kidney disease on dialysis.
The expanded financing comes ahead of topline data from a global Phase 2b trial, which is expected in the first half of 2027. The trial, being conducted at clinical sites across the US and in China through R1's global partnership with Alebund Pharmaceuticals (Jiangsu) Limited (HKEX: 09637), aims to evaluate the efficacy of AP306. AP306 is designed to block three key phosphate transporters in the gut, potentially delivering rapid and effective phosphate lowering with a significantly reduced treatment burden.
Samsara BioCapital, a leading biotech investment firm, joins an investor syndicate that includes Abingworth, DaVita Venture Group, F-Prime, Curie.Bio, SNMA Capital (previously Symbiosis Capital Management), and U.S. Renal Care. The initial $77.5 million round announced in March 2026 was oversubscribed, and the additional $3 million brings the total to $80.5 million.
Phosphate binders have been the standard of care for 60 years,1 yet more than 70% of US dialysis patients fail to achieve normal phosphate levels,2 and uncontrolled hyperphosphatemia contributes to cardiovascular disease, bone disease, and mortality.3 AP306 is the only agent that blocks the "active" transport of phosphate, targeting three key transporters in the gut, with the potential for rapid, effective phosphate lowering at a substantially reduced treatment burden.
The multi-center, randomized, double-blind, placebo-controlled Phase 2b study (NCT06712654) is being conducted at clinical sites across the US and in China through R1's global partnership with Alebund Pharmaceuticals. The study is designed to evaluate the safety and efficacy of AP306 in patients with chronic kidney disease on dialysis. Topline data from the trial are expected in the first half of 2027.