Alebund Pharmaceuticals Announces Completion of Patient Enrollment in Global Phase III Pivotal Multi-Regional Clinical Trial of AP301 for Hyperphosphatemia

SHANGHAI, May 6, 2026 /PRNewswire/ -- Alebund Pharmaceuticals (Jiangsu) Limited ("Alebund" or the "Company"), an integrated biopharmaceutical company focusing on developing innovative therapies for the treatment of renal diseases and related chronic conditions, today announced the completion of patient enrollment in the global Phase III pivotal multi-regional clinical trial (RESPOND-2, Study AP301-HP-03) of AP301, a novel fiber-iron-based phosphate binder, for the treatment of hyperphosphatemia. The trial was conducted in the United States and China, led by Dr. Geoffrey A. Block of U.S. Renal Care, with Professor Xiaoqiang Ding, Director of the Department of Nephrology, Zhongshan Hospital, Fudan University serving as the China principal investigator, and enrolled a total of 282 chronic kidney disease ("CKD") patients on maintenance dialysis with hyperphosphatemia — 138 in the U.S. and 144 in China.

As a next-generation fiber-iron-based phosphate binder, AP301 is designed to have a higher phosphate-binding capability, favorable gastrointestinal tolerability, minimal risk of iron overload, and no requirement for chewing before swallowing, with the potential to improve treatment adherence and effectively control hyperphosphatemia.

Trial Design

RESPOND-2 is a double-blind, randomized, multi-regional Phase III clinical trial conducted in the U.S. and China. The study planned to enroll 264 CKD patients aged 12 years and above on maintenance dialysis with hyperphosphatemia, with 282 patients actually enrolled. The study comprises three treatment phases: an 8-week double-blind dose titration phase (AP301 versus AP301 ineffective low dose, 2:1 randomization), a 24-week open-label treatment phase, and a 3-week double-blind randomized withdrawal phase (AP301 maintenance dose versus AP301 ineffective low dose, 1:1 re-randomization). The primary endpoint is the change in serum phosphate levels from baseline to the end of the dose titration phase (AP301 versus AP301 ineffective low dose). The key secondary endpoint is the change in serum phosphate level from the end of the open-label treatment phase to the end of the randomized withdrawal phase (AP301 maintenance dose versus AP301 ineffective low dose).

Based on existing clinical data for AP301, the Company reached an agreement with the FDA that this global Phase III multi-regional clinical trial will serve as the single pivotal study to support U.S. registration of AP301.

Unmet Medical Need

Hyperphosphatemia is one of the most common complications in CKD patients, affecting approximately 95% of dialysis-dependent CKD patients and approximately 15% of non-dialysis CKD patients. According to KDIGO (Kidney Disease: Improving Global Outcomes) guidelines, hyperphosphatemia is defined as a serum phosphate level exceeding 4.5 mg/dL (1.45 mmol/L), with the target serum phosphate range for dialysis patients being 3.5–5.5 mg/dL (1.13–1.78 mmol/L) ^[1]. Chronically elevated serum phosphate is a central driver of CKD-mineral and bone disorder (CKD-MBD), leading to serious complications including vascular calcification, secondary hyperparathyroidism, and renal osteodystrophy, and is an independent risk factor for cardiovascular events and all-cause mortality in dialysis patients ^[2].

For CKD patients on dialysis, regular dialysis alone is insufficient to clear the accumulated phosphorus in the body, and the effect of dietary phosphorus restriction is limited. Oral phosphate binders remain the primary treatment for hyperphosphatemia. However, existing phosphate binders are commonly associated with gastrointestinal side effects, high pill burden, and systemic absorption in some agents, resulting in poor patient compliance and inadequate treatment duration. According to the Dialysis Outcomes and Practice Patterns Study (DOPPS) data, approximately 76% of dialysis patients in China, 52% in the U.S., and 39% in Japan fail to achieve target serum phosphate levels ^[3]. Data from the China Dialysis Calcification Study (CDCS) further showed that the serum phosphate us target attainment rate among Chinese dialysis patients within the 3.5–5.5 mg/dL range was only 40.1% ^[4].

Data from the Completed AP301 China Pivotal Phase III Clinical Trial

AP301 demonstrated robust and clinically meaningful efficacy in the completed China pivotal Phase III clinical trial (RESPOND-1, Study AP301-HP-02) ^[5]. The study was led by Professor Li Zuo, Director of the Department of Nephrology at Peking University People's Hospital, and randomized 474 participants across 50 investigational sites in China.

At Week 12, AP301 was non-inferior to sevelamer carbonate, a phosphate binder widely used in clinical practice, in reducing serum phosphate levels (reductions from baseline of -0.72 mmol/L [-2.22 mg/dL]  vs. -0.70 mmol/L [-2.17 mg/dL]), respectively; the upper bound of the 95% confidence interval (CI) for the between-group difference (0.06 mmol/L [0.20 mg/dL]) was below the pre-defined non-inferiority margin of 0.19 mmol/L (0.59 mg/dL), demonstrating that AP301 met the pre-specified non-inferiority criterion versus sevelamer carbonate. At Week 27, participants receiving the AP301 maintenance dose achieved clinically and statistically superior serum phosphate control compared with the ineffective low dose group, with a between-group difference of -0.58 mmol/L (-1.8 mg/dL) (P<0.001). At the end of Week 52, the AP301 group showed a greater mean reduction in serum phosphate level from baseline than the sevelamer carbonate group (-0.76 mmol/L vs. -0.72 mmol/L), a higher serum phosphate target attainment rate (66.7% vs. 58.6%), and a lower daily dose (AP301 6.52 g/day vs. sevelamer carbonate 7.56 g/day). AP301 achieved robust and sustained serum phosphate reduction, suggesting its long-term therapeutic benefit.

Overall, AP301 was safe and well-tolerated. The most common adverse events were discolored feces and diarrhea. Diarrhea typically occurred within the first 2 to 4 weeks of treatment, was predominantly mild in severity, resolved without treatment modification, and rarely led to treatment discontinuation (0.6%). In the 52-week Phase III treatment period, no safety findings related to iron accumulation were observed.

Based on the results of AP301 China pivotal phase III clinical trial and other accumulated clinical data, Alebund has obtained alignment with NMPA and plans to submit a New Drug Application (NDA) in China in the near future.

Jin Tian, M.D., Co-founder and Chief Medical Officer of Alebund Pharmaceuticals, commented: "The on-time completion of patient enrollment in AP301's global Phase III pivotal multi-regional clinical trial reflects Alebund's ability to advance high-quality global clinical development, which is an important milestone in the global registrational development of AP301."

About Hyperphosphatemia

Hyperphosphatemia is one of the most common complications in CKD patients. The long-term elevated serum phosphate levels could cause multiple complications such as secondary hyperparathyroidism, renal osteodystrophy, and vascular calcification. It is an independent risk factor of cardiovascular events and all-cause mortalities. Good control of serum phosphate levels could effectively improve the patients' outcome. For CKD patients undergoing dialysis treatment, regular dialysis is not sufficient to remove the excess serum phosphate in the body. Considering the limitations of low-phosphate diet which might cause dystrophia, oral use of phosphate binders is the prevailing treatment for hyperphosphatemia. However, existing phosphate binders lead to low patient compliance, with less than 50% of patients achieving good phosphate control, due to gastrointestinal side effects and high pill burden, etc.

According to the Global and Chinese Hyperphosphatemia Drug Industry Blue Book by China Insights Consultancy in 2023, the out-of-target rate of serum phosphate level in dialysis patients in Chinese mainland was significantly higher than that in other countries and regions. There remains substantial room for improvement in terms of the proportion of patients using phosphate binders and duration of their usage. According to CIC, by 2035, the market size of serum phosphorus-lowering products in China is expected to reach RMB 10 billion while the global market size is forecasted to reach USD 6 billion.

About Alebund Pharmaceuticals

Alebund was founded in Shanghai in 2018. The Company focuses on the discovery, development, manufacturing, and commercialization of novel therapies primarily for kidney diseases and their complications, as well as other chronic conditions, to bring better therapeutic options to patients in China and globally. Alebund has built a diversified and balanced pipeline of seven drug candidates and one commercialized product (Mircera®) targeting a broad range of renal indications, including chronic kidney disease (CKD) and CKD complications, such as hyperphosphatemia, renal anemia, IgA nephropathy, diabetic kidney disease, focal segmental glomerulosclerosis (FSGS), and autosomal dominant polycystic kidney disease (ADPKD). Alebund has completed the construction of its manufacturing site in Yangzhou that will supply both drug substance and drug products of our product candidates, including AP301, upon commercial launch. Alebund has also established a dedicated in-house commercialization team in China responsible for promoting our renal products.

CONTACT: [email protected]

SOURCE Alebund Pharmaceuticals