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Abstract: TH-PO144

Tenapanor Effect on Decrease in Phosphate Binder Pill Burden for Hyperphosphatemia in Japanese Patients Undergoing Hemodialysis: A Phase 3 Long-Term Study

Session Information

Category: Bone and Mineral Metabolism

  • 502 Bone and Mineral Metabolism: Clinical


  • Yokoyama, Keitaro, The Jikei University School of Medicine, Tokyo, Japan
  • Sato, Yu, Kyowa Kirin Co., Ltd., Tokyo, Japan
  • Ohara, Meiko, 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

Phosphate binders (PBs) are commonly prescribed for treating hyperphosphatemia. However, management with PBs often requires a high pill burden which is a significant issue in hemodialysis (HD) patients. Tenapanor (TEN) is a novel drug that reduces paracellular phosphorus absorption via the selective inhibition of sodium/hydrogen exchanger isoform 3, and the dose consists of one small tablet taken twice daily. We aimed to evaluate the ability of TEN to decrease PB pill burden for hyperphosphatemia in Japanese HD patients in the long-term safety study.


This was a multicenter, open-label, single-arm, phase 3 study. HD patients whose serum phosphorus level was 3.5−7.0 mg/dL at baseline received TEN 5 mg BID added to their PB regimen. The TEN dose was titrated in a stepwise manner within the range of 5, 10, 20 and 30 mg BID. The dose of TEN and PBs was adjusted based on serum phosphorus levels from Week 2, while controlling serum phosphorus levels and switching from PBs to TEN. While the primary endpoint was safety of the 52-week TEN treatment, the key secondary endpoint was a ≥30% reduction in the total pill number of daily PBs and TEN from baseline.


Overall, 212 patients started treatment, and 154 patients completed the study. At Week 52 or the time of discontinuation, 158 patients (77.5%) achieved a ≥30% reduction in the total daily pill number of PBs and TEN. Complete switching from PBs to TEN was achieved in 93 patients (45.6%). From Week 0 to Week 52, the mean (SD) daily pill number of PBs decreased from 11.4 (7.62) to 3.1 (5.48). Mean (SD) serum phosphorus levels were well controlled, 5.24 (0.96), 4.01 (1.14), and 5.11 (1.17) mg/dL at baseline, Week 2, and Week 52, respectively. The major drug-related adverse event was diarrhea (56.6%), and most events were mild in severity. Nine patients (4.2%) discontinued because of diarrhea. There were no clinically relevant changes other than serum phosphorus level for study period.


TEN demonstrated its ability to significantly decrease the pill number of PBs and was well tolerated in the long-term administration. These results suggest that TEN could achieve the dual targets of decreasing PB pill burden and controlling serum phosphorus levels.


  • Commercial Support – Kyowa Kirin Co., Ltd.