Ardelyx, Inc.

R1 Therapeutics CEO Krishna Polu, M.D., said the company\'s lead candidate “represents a fundamentally new approach to treating hyperphosphatemia.”\n R1 Therapeutics is debuting with an oversubscribed $77.5 million series A financing aimed at advancing its first-in-class therapy for chronic kidney disease (CKD) patients on dialysis with high phosphate levels.The funding was co-led by Abingworth, F-Prime Capital and DaVita Venture Group, with participation from Curie.Bio, SymBiosis and U.S. Renal Care, according to a March 17 release.The financing arrives alongside the new company obtaining an exclusive global license to develop and commercialize an asset called AP306 from China-based Alebund Pharmaceuticals. The candidate is a pan-phosphate transporter inhibitor in development as a monotherapy for hyperphosphatemia, a condition characterized by elevated phosphorus levels in the blood that can cause muscle cramps, itchy skin, bone pain and rashes.Hyperphosphatemia is common among the roughly 500,000 patients in the U.S. and 4 million people worldwide who are on dialysis, and the condition can lead to bone and cardiovascular disease. AP306 was originally developed by Chugai Pharmaceutical, which later licensed it to Alebund, and is expected to enter a phase 2b study later this year. Alebund published phase 2a data on the asset in January 2025, demonstrating a significant reduction in serum phosphate levels along with favorable safety and tolerability. According to the release, AP306 is the only agent that blocks the “active” transport of phosphate for the treatment of CKD, whereas approved therapies inhibit the “passive” transport of phosphate through binding. R1 notes that patients who take available phosphate binders, which were developed about 60 years ago, suffer from poor adherence due to high pill burdens and gastrointestinal tolerability issues, limiting their effectiveness.The biotech is led by co-founder and CEO Krishna Polu, M.D., a nephrologist who has served as an advisor to Abingworth since April and has more than 20 years of experience in the biopharma industry. Polu highlighted the support of global kidney care providers DaVita and U.S. Renal Care and said, “AP306 represents a fundamentally new approach to treating hyperphosphatemia.”R1\'s AP306 will look to avoid the fate of two hyperphosphatemia treatment predecessors. Unicycive Therapeutics received a complete response letter (CRL) from the FDA last year as it advanced its hyperphosphatemia treatment candidate for CKD patients on dialysis. The FDA cited issues at a third-party manufacturing vendor that were flagged during an inspection. Unicycive resubmitted its new drug application and the FDA is expected to make an approval decision by or before June 29, 2026.In 2021, Ardelyx also fell short of the FDA’s standards when its hyperphosphatemia candidate received a complete response letter stating the treatment effect was “small and of unclear clinical significance.\" However, the treatment, designed to treat an electrolyte disorder that affects patients on dialysis by inhibiting the sodium-proton exchanger NHE3, was eventually approved in 2023 and is now sold as Xphozah. R1\'s lead investors bring deep pockets and expertise. Abingworth was acquired by the Carlyle Group and its $477 billion assets under management in 2022, and DaVita Venture Group has experience in renal biotechs, including joining kidney-focused Pathalys Pharma\'s $105 million raise in 2024. Fidelity Biosciences rebranded as F-Prime in 2015 and has been responsible for 51 IPOs throughout its history, according to its website. 

R1 Therapeutics launched Tuesday with $77.5 million in hand and a lead asset called AP306 that it believes will improve outcomes for chronic kidney disease (CKD) patients by controlling hyperphosphataemia via a new mechanism. Rather than depending on the burdensome binder drugs patients have used for years, the California-based biotech aims to block phosphate absorption directly in the gut.It also announced a partnership with Alebund Pharmaceuticals to license global rights to AP306 outside China. Although exact terms of the deal weren't disclosed, Alebund said that it is eligible to receive milestone payments of up to low triple-digit millions of US dollars, as well as tiered sales royalties in the low double-digit percentage range. Alebund added that it also holds "a substantial non-dilutive equity interest in R1."AP306, also known as EOS789, is designed to inhibit all three phosphate transporters — NaPi-IIb, PiT-1 and PiT-2 — blocking phosphate uptake in the gut. It was discovered by Chugai Pharmaceutical and licensed to Alebund in 2021 for an undisclosed upfront payment and potential milestones.Current phosphate binders have been the standard of care for 60 years, but are limited by low binding capacity, high pill burden and poor gastrointestinal (GI) tolerability. More recently, Ardelyx's Xphozah (tenapanor) was approved by the FDA to lower serum phosphorus in CKD patients on dialysis as an add-on therapy that targets the NHE3 sodium transporter, though R1 says managing hyperphosphataemia continues to be an area of high unmet need."By blocking the active transport of phosphate through three different phosphate transporters in the GI tract, initial clinical studies suggest AP306 has the potential to deliver superior efficacy with substantially lower pill burden compared to current phosphate binder therapies," said R1 CEO Krishna Polu, adding the experimental drug, if successful, "should redefine the class of phosphate lowering therapies."Advancing to Phase IIbIn a Phase IIa study in dialysis patients, AP306 met its primary endpoint, reducing serum phosphate by 2.51 mg/dL from baseline at 12 weeks in haemodialysis patients with hyperphosphataemia, compared with a 1.08 mg/dL reduction for Sanofi's phosphate binder Renagel/Renvela (sevelamer). The study also suggested AP306 was safe and well tolerated, with a markedly lower dose burden than standard binders, which often require patients to take up to nine to 15 pills a day, R1 says on its website.A Phase IIb study of AP306 as monotherapy for hyperphosphatemia in patients with CKD is slated to start later this year in the US and China, with Alebund serving as a collaborative development partner on the drug.The oversubscribed series A financing was co-led by Abingworth, F-Prime and DaVita Venture Group, with participation from Curie.Bio, SymBiosis and US Renal Care.

R1 Therapeutics, a newly formed clinical-stage company, has licensed exclusive rights to develop and commercialize Alebund Pharmaceuticals’ AP306 outside Greater China under a collaboration and license agreement announced March 17, 2026. AP306 is a first-in-class pan-phosphate transporter inhibitor in development for hyperphosphatemia in patients with chronic kidney disease on dialysis. Shanghai-based Alebund retains all rights in Greater China. The licensing deal comes alongside’s R1 Therapeutics’ official launch following an oversubscribed USD 77.5 million Series A financing announced on the same day. The financing was co-led by Abingworth, DaVita Venture Group, and F-Prime, with participation from Curie.Bio, SymBiosis, and US Renal Care. Under the license deal, the aggregate financial terms include development, regulatory, and commercial milestone payments of up to low triple-digit millions of US dollars, specifics not disclosed. Alebund will receive tiered royalties in the low double-digit percentage range on net sales of AP306 in R1’s territory. Alebund will also receive a non-dilutive equity interest in R1, with the right to participate in future commercial upside through dividends. R1 will fund and lead global clinical development, with Alebund serving as a collaborative development partner. A global Phase IIb multi-regional clinical trial in the US and China is planned to initiate later in 2026. The deal context AP306 is a small molecule originally discovered by Chugai Pharmaceutical and subsequently licensed to Alebund in a 2021 deal. The compound inhibits three intestinal phosphate transporters — NaPi-IIb, PiT-1, and PiT-2 — that mediate active phosphate absorption in the gastrointestinal tract. In patients with chronic kidney disease on dialysis, impaired renal phosphate excretion leads to hyperphosphatemia, a condition associated with vascular calcification and cardiovascular complications. Current standard-of-care phosphate binders require patients to take multiple large pills with each meal, and adherence remains poor. AP306 targets the transcellular absorption pathway directly rather than binding phosphate in the gut lumen, representing a distinct pharmacological approach to hyperphosphatemia treatment in CKD. Alebund completed a Phase IIa trial in hemodialysis patients that demonstrated reductions in serum phosphorus with acceptable safety and tolerability. Results were published in Kidney International Reportspublication) and presented at the 61st European Renal Association Annual Congress). A Phase I ADME study in healthy subjects is also ongoing). The Alebund-R1 collaboration positions AP306 as R1’s lead program. R1’s investor syndicate includes DaVita, which serves approximately 295,000 patients across more than 3,200 dialysis centers globally, and US Renal Care, the largest privately held dialysis provider in the United States. Their involvement as both investors and kidney care providers could facilitate clinical trial enrollment and eventual commercial access. Alebund maintains a broader renal pipeline that includes AP301, an oral phosphate binder in global Phase III, and AP303, a dual PPAR agonist with US FDA Orphan Drug Designation for autosomal dominant polycystic kidney disease. The AP306 chronic kidney disease program enters a competitive landscape where Ardelyx’s tenapanor (XPHOZAH), an NHE3 inhibitor that blocks paracellular phosphate transport, is the only approved non-binder therapy for hyperphosphatemia in dialysis patients. Two earlier NaPi-IIb-selective inhibitors — Daiichi Sankyo’s DS-2330b and Astellas’ ASP3325 — failed to show adequate clinical efficacy, which may reflect the limitations of targeting a single transporter rather than all three. AP306’s pan-transporter inhibition is designed to prevent compensatory upregulation of untargeted transporters, a mechanism that may have contributed to the failure of single-target approaches. The planned Phase IIb trial will need to confirm whether this broader inhibition profile translates into clinically meaningful phosphate reduction beyond what existing therapies achieve. Leave a Reply Cancel reply Your email address will not be published. Required fields are marked * Comment * Name * Email * Website