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Real-world analysis showed serum phosphate reductions following XPHOZAH initiation across all phosphate binder groups evaluated

Additional data highlighted the challenges of managing hyperphosphatemia and the morbidity and mortality risks associated with long-term elevated phosphorus

WALTHAM, Mass., Oct. 23, 2026 (GLOBE NEWSWIRE) -- Ardelyx, Inc. (Nasdaq: ARDX), a commercial-stage biopharmaceutical company focused on the development and commercialization of innovative medicines that meet significant unmet medical needs, today announced results from a real-world analysis presented at the American Society of Nephrology (ASN) Kidney Week 2026 evaluating real-world serum phosphate outcomes among adults on dialysis who initiated XPHOZAH either without a phosphate binder or as add-on therapy to a single phosphate binder. Ardelyx also presented data on the challenges patients experience in managing hyperphosphatemia, as well as the association between long-term hyperphosphatemia and serious health outcomes in patients on dialysis, including morbidity and mortality.

"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," said Rajani Dinavahi, MD, Chief Medical Officer of Ardelyx. "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 real-world analysis looked at serum phosphate outcomes in more than 1,400 adults on dialysis with hyperphosphatemia who started tenapanor either without a phosphate binder or alongside a single phosphate binder. Across all treatment groups, serum phosphate levels declined over six months of follow-up, with adjusted mean reductions at month six ranging from 0.80 to 1.55 mg/dL. The adjusted probability of reaching a serum phosphate level below 5.5 mg/dL ranged from 16% to 41% across groups, and 60% to 70% of patients remained on tenapanor at 180 days. The probability of remaining on tenapanor at 180 days was comparable across phosphate-binder groups. Overall, similar serum phosphate reductions were observed across the phosphate-binder groups evaluated, including among patients who initiated tenapanor without a phosphate binder.

Presentations at ASN 2026 include:

Presentation Title	Authors	Poster Number	Presentation Details
Real-World Effectiveness of Tenapanor: Serum Phosphate Outcomes by Existing Phosphate Binder Use	Alan Fossa, Dhajanae Sylvertooth, Angelo Karaboyas, Roberto Pecoits-Filho, Luisa L. Scott	FR-PO0317	Poster, Oct 23, 10:00 AM to 12:00 PM MDT
Patient Perspectives on Hyperphosphatemia Management in a Contemporary End-Stage Kidney Disease Cohort: Results of an Online Survey	Nissreen Elfadawy, Jaime Uribarri, Janet Diaz-Martinez, Asa Renfroe, Emily Belcher, Luisa L. Scott	FR-PO0324	Poster, Oct 23, 10:00 AM to 12:00 PM MDT
Morbidity and Mortality Risks Associated with Cumulative Hyperphosphatemia in a Contemporary Cohort of US Dialysis Patients	Julia Scialla, Bernard Jaar, Nan Ji, Roberto Pecoits-Filho, Keith McCullough, Luisa L. Scott	FR-PO0316	Poster, Oct 23, 10:00 AM to 12:00 PM MDT

The posters are available on the ASN Kidney Week 2026 website here.

About XPHOZAH® (tenapanor)
XPHOZAH® (tenapanor) is the first and only phosphate absorption inhibitor (PAI) approved by the U.S. Food and Drug Administration to reduce serum phosphorus in adults with chronic kidney disease (CKD) on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. With a differentiated mechanism of action, XPHOZAH blocks phosphate absorption through the paracellular pathway, the primary pathway of phosphate absorption, and is administered as one tablet taken twice daily. Diarrhea was the most common side effect experienced by patients taking XPHOZAH in clinical trials. Please see Important Safety Information below and click for full Prescribing Information.

About Hyperphosphatemia
Hyperphosphatemia is a serious condition characterized by elevated levels of phosphate in the blood that affects many of the approximately 550,000 people in the United States with chronic kidney disease (CKD) on maintenance dialysis. As kidney function declines, the kidneys are unable to adequately eliminate excess phosphate, leading to its accumulation in the blood. Elevated phosphate levels are associated with adverse clinical outcomes in patients with CKD on dialysis. International KDIGO treatment guidelines recommend lowering progressively or persistently elevated serum phosphate toward the laboratory-specific normal range. In adults, a commonly used reference range is approximately 2.5–4.5 mg/dL.

IMPORTANT SAFETY INFORMATION
CONTRAINDICATIONS
XPHOZAH is contraindicated in:

• Pediatric patients under 6 years of age
• Patients with known or suspected mechanical gastrointestinal obstruction
  
  

WARNINGS AND PRECAUTIONS
Diarrhea
Patients may experience severe diarrhea. Treatment with XPHOZAH should be discontinued in patients who develop severe diarrhea.

MOST COMMON ADVERSE REACTIONS
Diarrhea, which occurred in 43-53% of patients, was the only adverse reaction reported in at least 5% of XPHOZAH-treated patients with CKD on dialysis across trials. The majority of diarrhea events in the XPHOZAH-treated patients were reported to be mild-to-moderate in severity and resolved over time, or with dose reduction. Diarrhea was typically reported soon after initiation but could occur at any time during treatment with XPHOZAH. Severe diarrhea was reported in 5% of XPHOZAH-treated patients in these trials.

INDICATION
XPHOZAH (tenapanor), 30 mg BID, is indicated to reduce serum phosphorus in adults with chronic kidney disease (CKD) on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy.

For additional safety information, please see full Prescribing Information.

About Ardelyx
Ardelyx is a commercial-stage biopharmaceutical company focused on the development and commercialization of innovative medicines that meet significant unmet medical needs. Ardelyx has two commercial products approved in the United States, IBSRELA® (tenapanor) and XPHOZAH® (tenapanor). The company’s pipeline includes the Phase 3 development of IBSRELA for chronic idiopathic constipation (CIC) and RDX10531, a next-generation NHE3 inhibitor with potential application across multiple therapeutic areas. Ardelyx works with its partners to develop and commercialize its products outside of the United States. For more information, please visit https://ardelyx.com/ and connect with us on X (formerly known as Twitter), LinkedIn and Facebook.

Forward Looking Statements
To the extent that statements contained in this press release are not descriptions of historical facts regarding Ardelyx, they are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor of the Private Securities Litigation Reform Act of 1995, including Ardelyx’s current expectations regarding: the presentation sessions at ASN Kidney Week 2026, including their timing and content; any clinical implications of the real-world or other analyses described in this press release; and our ongoing development programs. Such forward-looking statements involve known and unknown risks, uncertainties and other factors that are in some cases beyond our control, that could cause actual outcomes or results to differ materially from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, uncertainties associated with the development of, regulatory process for, and commercialization of drugs in the U.S. and internationally, and the risk that real-world, post hoc, observational, survey or other analyses may not be indicative of future results or outcomes in broader patient populations, or may be interpreted differently by others. Ardelyx undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to Ardelyx’s business in general, please refer to Ardelyx's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on August 6, 2026, and its future current and periodic reports to be filed with the Securities and Exchange Commission.

Investor Contact:
Lisa Caperelli
SVP, Investor Relations & Corporate Communications
lcaperelli@ardelyx.com

Media Contact:
Lindsey Manuel
Associate Director, Corporate Communications
lmanuel@ardelyx.com