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Abstract: FR-PO318

Tenapanor in Combination with Phosphate Binders Improves Short- and Long-Term Control of Serum Phosphate (sP) in Patients on Dialysis with Hyperphosphatemia

Session Information

Category: Bone and Mineral Metabolism

  • 502 Bone and Mineral Metabolism: Clinical

Authors

  • Weiner, Daniel E., Tufts Medical Center, Boston, Massachusetts, United States
  • Lynn, Robert I., Kidney Medical Associates, Bronx, New York, United States
  • Spiegel, David M., Ardelyx, Inc., Waltham, Massachusetts, United States
  • Edelstein, Susan A., Ardelyx, Inc., Waltham, Massachusetts, United States
  • Yang, Yang, Ardelyx, Inc., Waltham, Massachusetts, United States
  • Rosenbaum, David P., Ardelyx, Inc., Waltham, Massachusetts, United States
Background

Tenapanor (TEN) is a phosphate absorption inhibitor that blocks paracellular phosphate absorption by local inhibition of the intestinal sodium hydrogen exchanger isoform 3 (NHE3). In the 4-week AMPLIFY (NCT03824587) study, TEN in combination with the phosphate binder (PB) sevelamer (SEV) allowed more patients (pts) to achieve target sP. The NORMALIZE (NCT03988920) extension study was designed to help pts achieve sP ≤4.5 mg/dL (relaxed to ≤5.5 mg/dL with protocol amendment). Pts who completed the 1-year safety comparator arm (SEV) of PHREEDOM added TEN to control sP for up to 18 months. We report early and long-term control of sP in the subset of PHREEDOM pts who were inadequately controlled (sP >4.5 mg/dL) on SEV monotherapy.

Methods

61 pts from the SEV arm of PHREEDOM (NCT03427125) entered NORMALIZE. Of these 61 pts, 43 (70.5%) had sP >4.5 mg/dL at NORMALIZE baseline when TEN 30 mg bid was added to the SEV dose. After starting TEN, SEV was decreased as long as sP was controlled, with the intention to decrease/eliminate SEV if possible. TEN could be up- or down-titrated in 10 mg increments, with a maximum dose of 30 mg bid, based on sP level and/or tolerability.

Results

Of the 43 pts entering NORMALIZE with sP >4.5 mg/dL, median baseline SEV use was 9 pills/day, dropping to 6 pills/day at the end of NORMALIZE. Percentage of pts achieving sP ≤4.5 mg/dL at each study visit is shown in the Figure. Adverse events reported were similar to those seen in other TEN studies; no new safety issues were identified.

Conclusion

The NORMALIZE study confirms the findings from AMPLIFY that TEN in combination with SEV enables a greater percentage of pts to achieve sP ≤4.5 mg/dL with no new safety issues. These data also demonstrate that TEN in combination with SEV can achieve long-term sP control in patients when SEV monotherapy fails to normalize sP.

Funding

  • Commercial Support – Ardelyx, Inc.