Shanghai, China, and Denver, Colorado, USA, October 23, 2026
Alebund Pharmaceuticals and R1 Therapeutics have announced the presentation of the clinical trial design for AP306, an investigational oral therapy being developed to treat hyperphosphatemia in patients with chronic kidney disease (CKD) receiving maintenance hemodialysis. The study design was presented as a trial-in-progress poster at the American Society of Nephrology’s (ASN) Kidney Week 2026 meeting in Denver, Colorado. The global Phase 2b, multicenter clinical trial is evaluating the safety, tolerability and phosphate-lowering effects of AP306. The program aims to address persistent treatment challenges associated with elevated blood phosphate levels, a common complication among patients receiving dialysis. AP306 is a first-in-class oral pan-phosphate transporter inhibitor designed to reduce intestinal phosphate absorption through a different mechanism from conventional phosphate binders. The study is being conducted at clinical centers in the United States and China, with approximately 168 participants planned for enrollment. The companies expect the trial to provide important information for selecting appropriate doses and dosing schedules for subsequent clinical development.
Phase 2b Trial Evaluates AP306 in Dialysis Patients
The global Phase 2b study, registered as NCT06712654, is a randomized, double-blind, placebo-controlled clinical trial designed to evaluate multiple fixed doses of AP306 in patients with hyperphosphatemia who receive maintenance hemodialysis. Approximately 168 participants are expected to be assigned across six AP306 dose groups and one placebo group. The treatment period will last eight weeks, allowing investigators to assess changes in serum phosphate concentrations and evaluate the tolerability of different dosing regimens. The primary endpoint is the change in serum phosphate levels from baseline to the end of treatment. Secondary endpoints include the proportion of participants who achieve the target serum phosphate range and the time required to reach phosphate control. Researchers will also assess safety, tolerability and the relationship between dose and treatment response. The trial includes both twice-daily and three-times-daily dosing schedules, enabling investigators to compare their effects and identify a regimen that balances phosphate reduction with practical treatment requirements. The China portion of the study is led by Peking University People’s Hospital and includes seven clinical centers. Recruitment is underway in both countries, following the randomization and dosing of the first participant announced in July 2026. The companies expect the study to be completed in the second quarter of 2027, with top-line findings to be announced when available.
Novel Mechanism Targets Three Intestinal Phosphate Transporters
AP306, formerly known as EOS789, was originally discovered by Chugai Pharmaceutical and subsequently licensed to Alebund Pharmaceuticals, which holds global development, manufacturing and commercialization rights under its agreement. The candidate is designed to inhibit three key intestinal phosphate transporters: NaPi-IIb, PiT-1 and PiT-2. These transport proteins contribute to the active absorption of phosphate from the gastrointestinal tract into the body. By inhibiting all three transporters, AP306 aims to reduce intestinal phosphate absorption through a mechanism that differs from conventional phosphate binders, which work by binding dietary phosphate within the digestive tract. The approach could offer an alternative strategy for managing elevated phosphate levels in patients with advanced kidney disease. The potential advantage of AP306 is its transporter-targeting mechanism, which may help reduce the burden associated with existing phosphate-binding therapies. However, the clinical effectiveness, safety and optimal administration schedule of AP306 must be established through controlled clinical studies. The current Phase 2b trial is intended to generate dose-response information that can guide the selection of regimens for later-stage research.
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Addressing Unmet Needs in Chronic Kidney Disease Care
Hyperphosphatemia is a significant complication of advanced CKD, particularly among patients receiving long-term dialysis. When kidney function declines, the body becomes less able to remove excess phosphate, potentially contributing to mineral and bone disorders, vascular calcification and cardiovascular complications. Although dialysis, dietary phosphate restriction and phosphate-binding medications are widely used, many patients struggle to maintain phosphate concentrations within recommended ranges. High pill burden, gastrointestinal tolerability and difficulties maintaining long-term treatment adherence remain important limitations of existing approaches. AP306 is being developed to provide a differentiated oral treatment option that may improve phosphate control and reduce the daily medication burden, depending on the eventual clinical results and approved dosing regimen. Under the licensing agreement established in December 2025, Alebund retains rights to AP306 in mainland China, Hong Kong, Macau and Taiwan, while R1 Therapeutics holds exclusive rights to develop, manufacture and commercialize the candidate in other regions. Both companies are co-sponsors of the global Phase 2b trial and share responsibilities for clinical execution and regulatory support within their respective territories. AP306 remains investigational and is not an approved treatment. The ongoing study will be essential to determining whether its mechanism translates into clinically meaningful phosphate reduction and an acceptable safety profile for patients receiving maintenance hemodialysis.
Source: Alebund Pharmaceuticals, R1 Therapeutics press release
