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Abstract: TH-PO161

Efficacy and Safety of Tenapanor Added to Phosphate Binders for Hemodialysis Patients Who Have Poorly Controlled Hyperphosphatemia on Existing Phosphate Binders: Results of a Randomized Phase 3 Trial

Session Information

  • CKD-MBD: Targets and Outcomes
    November 03, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical


  • Kazama, Junichiro James, Fukushima Medical University, Fukushima, Japan
  • Kusakabe, Miho, Kyowa Kirin Co., Ltd., Tokyo, Japan
  • Kinoshita, Jun, Kyowa Kirin Co., Ltd., Tokyo, Japan
  • Nakanishi, Kaoru, Kyowa Kirin Co., Ltd., Tokyo, Japan
  • Fukagawa, Masafumi, Tokai University School of Medicine, Isehara, Japan
  • Akizawa, Tadao, Showa University School of Medicine, Tokyo, Japan

Despite the use of conventional phosphate binders (PB), phosphate management still remains a difficult issue among patients undergoing maintenance hemodialysis (HD) therapy. Tenapanor (TEN) selectively inhibits the intestinal sodium/hydrogen exchanger 3 and decreases paracellular phosphate absorption, which has a potential to improve phosphate management among those HD patients displaying hyperphosphatemia refractory to conventional PB. In this study, we evaluated the efficacy and safety of TEN added to PB for refractory hyperphosphatemia in Japanese HD patients.


This was a phase 3, randomized, multicenter, double-blind, placebo-controlled, parallel-group study. Patients whose serum phosphorus level was out of target range; 6.1−9.9 mg/dL on conventional PBs were eligible for this study. After a 2 weeks observation period, patients were randomized to TEN+PB or placebo + PB in 1:1 ratio. TEN was administered at initial dose of 5 mg twice a day and titrated within the range of 5, 10, 20, and 30 mg twice a day based on serum phosphorus levels, while the PB dosage was unchanged. The primary endpoint was the change in serum phosphorus level from baseline to week 8 after the start of TEN.


One-hundred and sixty-nine subjects were randomized. The mean change in the serum phosphorus level from baseline to week 8 was −2.00 mg/dL in the TEN group and −0.24 mg/dL in the placebo group. The difference in the mean change from baseline in serum phosphorus levels between the TEN and placebo groups was −1.76 mg/dL (95%CI [−2.16, −1.37 mg/dL], p<0.0001). The percentage achieving the target serum phosphorus level (3.5−6.0 mg/dL) after 8 weeks of treatment was 72.6% in the TEN group and 28.9% in the placebo group. Diarrhea was the most frequent adverse event (TEN=63.1%; placebo=14.1%), and all were of mild to moderate in severity.


TEN achieved a significant reduction in serum phosphorus levels compared with the placebo when added to PB therapy. This result suggests that TEN combined with PB could be a promising treatment option for hyperphosphatemia refractory to conventional PBs among HD patients.


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