Tenapanor Lowers Serum Phosphate Regardless of Binder Use in Dialysis

Tenapanor (Xphozah), a phosphate absorption inhibitor, reduced serum phosphate in adults on dialysis whether initiated alone or as add-on to any single phosphate binder, according to a real-world analysis presented at ASN Kidney Week 2026 in Denver, Colorado.¹

At month 6, adjusted mean reductions ranged from 0.80 to 1.55 mg/dL across binder groups.^1,2

"These findings add meaningful real-world evidence describing serum phosphate reductions following XPHOZAH initiation in patients both with and without a phosphate binder at baseline," Rajani Dinavahi, MD, Chief Medical Officer of Ardelyx, said in a statement.² "The broader research we presented at ASN Kidney Week also highlights how persistently difficult it is for patients to manage hyperphosphatemia, and the serious mortality and morbidity risks associated with cumulative phosphate burden. Taken together, these data reinforce the ongoing challenges of phosphate management and why we need more treatment options to help patients on dialysis gain control of their phosphate levels "

The US Food and Drug Administration approved tenapanor in October 2023 to reduce serum phosphorus in adults with chronic kidney disease on dialysis as add-on therapy for patients with an inadequate response to phosphate binders or intolerance of any binder dose.³ Tenapanor blocks phosphate absorption through the paracellular pathway, a mechanism complementary to binders.² Investigators noted evaluating real-world effectiveness by background binder type is of clinical importance.¹

How Did Tenapanor Perform Across Phosphate Binder Groups?

In this retrospective observational study, investigators from Arbor Research Collaborative for Health analyzed electronic health records from a mid-sized dialysis provider and a clinical data platform of independent dialysis organizations across the United States.¹ Eligible patients had baseline serum phosphate ≥ 5.5 mg/dL and initiated tenapanor between November 2023 and June 2025, either alone or as add-on to a single binder.

Patients also needed ≥ 1 serum phosphate measurement within 180 days of initiation.¹ Binder group was assigned according to baseline use, regardless of later changes. Average serum phosphate at baseline and each of months 1 through 6 formed the basis for all end points.

Patient characteristics among the 1477 included patients were similar across groups, although those receiving calcium-based binders had the highest median baseline serum phosphate, at 7.5 mg/dL.¹ All groups experienced serum phosphate reductions during follow-up.

At month 6, adjusted mean change in serum phosphate was −1.55 mg/dL (95% CI, −2.31 to −0.78) in the calcium-based binder group and −0.97 mg/dL (95% CI, −1.34 to −0.59) in patients starting tenapanor without a binder.¹ Reductions were −0.90 mg/dL (95% CI, −1.22 to −0.57) with sevelamer or lanthanum and −0.80 mg/dL (95% CI, −1.09 to −0.52) with iron-based binders.

How Many Patients Reached Phosphate Targets and Stayed on Tenapanor?

Across binder groups, the adjusted probability of achieving serum phosphate < 5.5 mg/dL ranged from 16% to 41%.¹ The probability of remaining on tenapanor through 180 days was comparable across binder types, at approximately 60% to 70%.

The investigators concluded tenapanor demonstrated similar effectiveness regardless of whether it was initiated with a binder or which binder was used.¹ They noted the results highlight a diversity of real-world use cases.

According to the prescribing information, tenapanor is dosed at 30 mg twice daily.² Diarrhea was the only adverse reaction reported in at least 5% of patients in clinical trials, occurring in 43% to 53%, with severe diarrhea in 5%.¹

As a retrospective study, the analysis is subject to limitations inherent to observational data, and Ardelyx noted real-world analyses may not predict results in broader populations.²

References

1. Fossa AJ, Sylvertooth D, Karaboyas A, et al. Real-world effectiveness of tenapanor: serum phosphate outcomes by existing phosphate binder use. Poster presented at: ASN Kidney Week 2026; October 21-25, 2026; Denver, CO. Poster FR-PO0317. doi:10.1681/ASN.2026jgkagred
2. Ardelyx. Ardelyx presents real-world data at ASN Kidney Week 2026 showing serum phosphate reductions following XPHOZAH (tenapanor) initiation with or without phosphate binders. GlobeNewswire. Published October 23, 2026. Accessed October 23, 2026. https://www.globenewswire.com/news-release/2026/10/23/3387604/0/en/ardelyx-presents-real-world-data-at-asn-kidney-week-2026-showing-serum-phosphate-reductions-following-xphozah-tenapanor-initiation-with-or-without-phosphate-binders.html
3. Brooks A. Tenapanor receives FDA approval for reducing serum phosphorous in CKD. HCPLive. Published October 17, 2023. Accessed October 23, 2026. https://www.hcplive.com/view/tenapanor-receives-fda-approval-for-reducing-serum-phosphorous-in-ckd