R1 Therapeutics has raised $77.5 million in oversubscribed Series A funding to develop AP306 against hyperphosphatemia in chronic kidney disease (CKD) patients on dialysis.[1][2] Funding is led by Abingworth, DaVita Venture Group and F-Prime, with participation from Curie.Bio, SymBiosis and the U.S. Renal Care.[2] R1 acquired exclusive global rights (outside of Greater China) to develop and commercialize AP306 from China's Alebund Pharmaceuticals.[1][3] AP306 is an inhibitor of three key phosphate transporters (NaPi-IIb, PiT-1, PiT-2) in the gut that blocks active phosphate transport, unlike existing phosphate binders that inhibit passive transport.[1][2][3] Hyperphosphatemia affects approximately 500,000 dialysis patients in the US and 4 million people worldwide and can lead to bone and cardiovascular disease.[1] Phase 2a data, published in January 2025, showed a significant reduction in serum phosphate levels with good safety and tolerability.[1][3] The funding will support global development, including a phase 2b study scheduled to begin later this year.[1][2][6]