ShanghaiMay 6, 2026 /PRNewswire/ — RemeGen (Jiangsu) Co., Ltd. (“RemeGen” or the “Company”), a comprehensive biopharmaceutical company focused on developing innovative drugs for kidney diseases and related chronic conditions, today announced that the global Phase III pivotal multi-regional clinical trial (RESPOND-2, trial number AP301-HP-03) of its novel oral iron-containing phosphate binder AP301 has completed full patient enrollment. The trial is being conducted simultaneously in the United States and China, led by Dr. Geoffrey A. Block of U.S. Renal Care, with Professor Ding Xiaoqiang, Director of the Department of Nephrology at Zhongshan Hospital, Fudan University, serving as the principal investigator in China. A total of 282 patients with chronic kidney disease (CKD) on maintenance dialysis with hyperphosphatemia were enrolled, including 138 in the United States and 144 in China.
As a next-generation oral phosphate binder based on iron-fiber technology, AP301 is designed to offer strong phosphate-binding capacity, good gastrointestinal tolerability, a very low risk of iron overload, and no need for chewing before swallowing, which is expected to improve patient treatment compliance and effectively control hyperphosphatemia.
Trial Design
RESPOND-2 is a double-blind, randomized, multi-regional Phase III clinical trial conducted in the United States and China. It planned to enroll 264 patients aged 12 years and older with CKD on maintenance dialysis and hyperphosphatemia, with 282 patients actually enrolled. The study includes three treatment phases: an 8-week double-blind dose titration period (AP301 vs. AP301 low-dose control, 2:1 randomization), a 24-week open-label treatment period, and a 3-week double-blind randomized withdrawal period (AP301 maintenance dose vs. AP301 low-dose control, 1:1 re-randomization). The primary endpoint is the change in serum phosphorus levels from baseline at the end of the titration period (AP301 group vs. AP301 low-dose control group). The key secondary endpoint is the change in serum phosphorus levels from the end of the open-label treatment period to the end of the randomized withdrawal period (AP301 maintenance dose group vs. AP301 low-dose control group).
Based on existing clinical data for AP301, the Company has reached an agreement with the FDA that this global Phase III pivotal multi-regional clinical trial will serve as the single pivotal study supporting the registration and marketing of AP301 in the United States.
Unmet Clinical Need
Hyperphosphatemia is one of the most common complications in CKD patients, affecting approximately 95% of dialysis-dependent CKD patients and about 15% of non-dialysis CKD patients. According to KDIGO (Kidney Disease: Improving Global Outcomes) guidelines, a serum phosphate concentration exceeding 4.5 mg/dL (1.45 mmol/L) is defined as hyperphosphatemia, with a target serum phosphorus range of 3.5–5.5 mg/dL (1.13–1.78 mmol/L) for dialysis patients[1]. Persistently high serum phosphorus levels are a core driver of CKD-mineral and bone disorder (CKD-MBD), leading to severe complications such as vascular calcification, hyperparathyroidism, and renal osteodystrophy, and are an independent risk factor for cardiovascular events and all-cause mortality in dialysis patients[2].
For CKD patients on dialysis, even regular dialysis cannot adequately remove accumulated phosphate from the body, and dietary phosphate restriction has limited efficacy. Oral phosphate binders are the primary treatment for hyperphosphatemia. However, existing phosphate binders commonly suffer from significant gastrointestinal side effects, high pill burden, and systemic absorption in some cases, leading to poor patient compliance and insufficient treatment duration. According to data from the Dialysis Outcomes and Practice Patterns Study (DOPPS), approximately 76% of dialysis patients in China, 52% in the United States, and 39% in Japan fail to achieve target serum phosphorus control[3]. Further data from the China Dialysis Calcification Study (CDCS) indicate that the serum phosphorus target achievement rate within the 3.5–5.5 mg/dL range is only 40.1% among dialysis patients in China[4].
Completed AP301 China Pivotal Phase III Clinical Trial Data
AP301 demonstrated robust and clinically meaningful efficacy in the completed China pivotal Phase III clinical study (RESPOND-1, trial number AP301-HP-02)[5]. The study was led by Professor Zuo Li, Director of the Department of Nephrology at Peking University People’s Hospital, and enrolled a total of 474 participants randomized across 50 research centers in China.
At Week 12 of treatment, AP301 was non-inferior to the widely used phosphate binder sevelamer carbonate in reducing serum phosphorus levels (mean reductions from baseline: -0.72 mmol/L [-2.22 mg/dL] vs. -0.70 mmol/L [-2.17 mg/dL]), with a 95% confidence interval (CI) upper limit for the between-group difference of 0.06 mmol/L (0.20 mg/dL), below the pre-specified non-inferiority margin of 0.19 mmol/L (0.59 mg/dL). This indicates that AP301’s phosphate-lowering efficacy met the pre-specified non-inferiority criterion compared to sevelamer carbonate. At Week 27, the difference between subjects receiving a maintenance dose of AP301 and the low-dose control group was -0.58 mmol/L (-1.8 mg/dL), achieving statistically and clinically superior serum phosphorus control (P<0.001). At the end of Week 52 of treatment, the mean reduction in serum phosphorus levels from baseline was greater in the AP301 group than in the sevelamer carbonate group (-0.76 mmol/L vs. -0.72 mmol/L), the serum phosphorus target achievement rate was higher in the AP301 group (66.7% vs. 58.6%), and the daily dose was lower (AP301 6.52 g/day, sevelamer carbonate 7.56 g/day). AP301 demonstrated robust and sustained phosphate-lowering effects, suggesting long-term therapeutic benefits.
Overall, AP301 was safe and well-tolerated. The most common adverse events were stool discoloration and diarrhea. Diarrhea typically occurred within the first 2 to 4 weeks of treatment, was mostly mild in severity, resolved without the need for treatment adjustment, and rarely led to treatment discontinuation (0.6%). No safety issues related to iron accumulation were observed during up to 52 weeks of Phase III treatment with AP301.
Based on the results of this China pivotal clinical study and other available clinical data, RemeGen and the NMPA have reached an agreement to submit a marketing authorization application for AP301 in China in the near future.
Dr. Tian Jin, Co-founder and Chief Medical Officer of RemeGen, stated: “The completion of full patient enrollment in the global Phase III pivotal multi-regional clinical trial of AP301 as planned demonstrates RemeGen’s execution capability in advancing high-quality clinical development on a global scale. This is a significant milestone in the global registration and development process of AP301.”
|
References |
|
[1] KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). Kidney Int Suppl. 2017;7(1):1-59. |
|
[5] Zuo L, et al. 52-Week Phase 3 Study to Evaluate the Efficacy and Safety of a Novel Iron-Based Phosphate Binder AP301 in Patients on Dialysis with Hyperphosphatemia. J Am Soc Nephrol. 2025;36(Abstract Suppl):TH-PO1200. Presented at ASN Kidney Week 2025, Houston, TX, November 6, 2025. |
About Hyperphosphatemia
Hyperphosphatemia is a major complication in patients with chronic kidney disease. Persistently high serum phosphorus levels can lead to various complications such as hyperparathyroidism, renal osteodystrophy, and vascular calcification, and are an independent risk factor for increased cardiovascular events and all-cause mortality. Achieving target serum phosphorus levels can effectively improve the prognosis of patients with chronic kidney disease. For hyperphosphatemia patients on dialysis for chronic kidney disease, even regular dialysis cannot eliminate the daily accumulation of ingested phosphate. Due to the limited efficacy of dietary phosphate restriction and its potential impact on nutritional status, oral phosphate binders are the primary treatment for hyperphosphatemia. However, more than half of patients have poor serum phosphorus control, primarily because existing phosphate binders cause significant gastrointestinal side effects and require a high number of pills, leading to poor treatment compliance. According to the 2023 “Global and China Hyperphosphatemia Drug Industry Blue Book” by CIC, the rate of uncontrolled serum phosphorus levels in dialysis patients in China is significantly higher than in other countries and regions, and there is still considerable room for improvement in both the proportion of phosphate binder use and the duration of medication use among patients. According to CIC, with the launch of next-generation phosphate-lowering products, the market size for phosphate-lowering drugs in China is expected to exceed 100 billion RMB by 2035, with the global market size projected to reach $6 billion.
About RemeGen
Founded in early 2018 in Shanghai, China, RemeGen is a biopharmaceutical company primarily dedicated to the discovery, development, manufacturing, and commercialization of innovative drugs for kidney diseases and related chronic conditions, aiming to provide better clinical treatment options for patients with chronic kidney disease and related disorders worldwide. RemeGen has established a rich and balanced pipeline of new drugs for kidney diseases, including seven investigational drugs and one marketed product (Mircera®). The company’s pipeline includes products targeting chronic kidney disease (CKD) and its complications, such as hyperphosphatemia, renal anemia, IgA nephropathy, diabetic nephropathy, focal segmental glomerulosclerosis (FSGS), and autosomal dominant polycystic kidney disease (ADPKD). RemeGen has built and activated a drug manufacturing base in Yangzhou to support the future commercialization of its pipeline products, including AP301. Additionally, RemeGen has established a specialized nephrology sales team responsible for the commercial promotion of related products in China.