Ardelyx to Share a Post-Hoc Analysis of the OPTIMIZE Study Supporting XPHOZAH® (tenapanor) at the National Kidney Foundation Spring Clinical Meetings

Rhea-AI Summary

Ardelyx (NASDAQ: ARDX) announced that a post-hoc analysis of their OPTIMIZE Study for XPHOZAH® (tenapanor) will be presented at the National Kidney Foundation Spring Clinical Meetings in April 2025. The study involved 330 patients with chronic kidney disease on dialysis with hyperphosphatemia.

XPHOZAH, the first and only phosphate absorption inhibitor (PAI), is FDA-approved to reduce serum phosphorus in adult CKD patients on dialysis as an add-on therapy. It's specifically indicated for patients with inadequate response to phosphate binders or those intolerant to binder therapy. The medication is administered as a single tablet twice daily.

The poster presentation will focus on how tenapanor-treated patients using over-the-counter antidiarrheal agents experienced decreased stool frequency and improved stool consistency. Additionally, Ardelyx will sponsor an Exhibitor Showcase discussing hyperphosphatemia management strategies and XPHOZAH's clinical application.

Positive

• FDA-approved first-in-class phosphate absorption inhibitor
• Simplified dosing regimen (single tablet twice daily)
• Demonstrated efficacy in managing phosphorus levels in CKD patients
• Shows potential benefits in stool-related side effects when combined with antidiarrheal agents

Negative

• Requires add-on antidiarrheal agents to manage side effects
• to use as add-on therapy rather than first-line treatment

WALTHAM, Mass., March 31, 2025 (GLOBE NEWSWIRE) -- Ardelyx, Inc. (Nasdaq: ARDX), a biopharmaceutical company founded with a mission to discover, develop and commercialize innovative, first-in-class medicines that meet significant unmet medical needs, today announced that an abstract detailing a post-hoc analysis of the OPTIMIZE Study, an open-label clinical trial of XPHOZAH ® (tenapanor), was accepted as a poster presentation at the National Kidney Foundation (NKF) Spring Clinical Meetings, to be held April 10-13, 2025, in Boston.

XPHOZAH, the first and only phosphate absorption inhibitor (PAI), is 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. XPHOZAH offers a different mechanism of action that blocks phosphate absorption at the primary pathway and is administered as a single tablet taken twice daily.

OPTIMIZE was a randomized, open label study, which included 330 patients with chronic kidney disease (CKD) on dialysis with hyperphosphatemia. The study was designed to evaluate different methods of initiating XPHOZAH to optimize phosphorus management in both binder-naïve and binder-treated patients. 

Title: Tenapanor-Treated Patients Using Over-the-Counter Antidiarrheal Agents Saw Decreased Stool Frequency and Improved Stool Consistency
Authors: Steven Fishbane, Suling Zhao, Susan Edelstein, Yang Yang, David Spiegel
Poster Number: G-310
Date/Time: April 10, 2025, from 5:15 to 7:30 PM EDT

Information regarding NKF Spring Clinical Meetings, including the presentation abstract, can be found here. 

In addition to the poster presentation during NKF Spring Clinical Meetings, Ardelyx is sponsoring an Exhibitor Showcase titled: “A Different Perspective on Hyperphosphatemia Management: Evaluating Current Strategies” on April 11, 2025, from 12:00-12:35 PM EDT, where Dr. Vincent Carsillo, will discuss first-in-class PAI, XPHOZAH. The presentation will review the XPHOZAH mechanism of action, efficacy and safety data from the Phase 3 clinical trial program and will include a discussion about the clinical application of XPHOZAH as add-on therapy for the many dialysis patients on a phosphate binder with serum phosphorus levels above guideline-established targets.

About XPHOZAH® (tenapanor)
XPHOZAH, discovered and developed by Ardelyx, is a first-in-class, phosphate absorption inhibitor with a differentiated mechanism of action that acts locally in the gut to inhibit the sodium hydrogen exchanger 3 (NHE3), thereby reducing phosphate absorption through the paracellular pathway, the primary pathway of phosphate absorption. XPHOZAH is a single tablet, taken twice daily. Diarrhea was the most common side effect experienced by patients taking XPHOZAH in clinical trials. Please see additional full Prescribing Information.

About Hyperphosphatemia
Hyperphosphatemia is a serious condition, defined as elevated levels of phosphate in the blood, which affects the vast majority of the 550,000 patients in the United States with chronic kidney disease (CKD) on maintenance dialysis. The kidneys are responsible for eliminating excess phosphate and as kidney function declines, phosphate is not adequately eliminated from the body. As a result, hyperphosphatemia is a nearly universal condition among people with CKD on maintenance dialysis, with internationally recognized KDIGO treatment guidelines that recommend lowering elevated phosphate levels toward the normal range (2.5-4.5mg/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 was founded with a mission to discover, develop and commercialize innovative, first-in-class medicines that meet significant unmet medical needs. Ardelyx has two commercial products approved in the United States, IBSRELA^® (tenapanor) and XPHOZAH^® (tenapanor). Ardelyx has agreements for the development and commercialization of tenapanor outside of the U.S. Kyowa Kirin commercializes PHOZEVEL^® (tenapanor) for hyperphosphatemia in Japan. A New Drug Application for tenapanor for hyperphosphatemia has been approved in China with Fosun Pharma. Knight Therapeutics commercializes IBSRELA in Canada. For more information, please visit https://ardelyx.com/ and connect with us on X (formerly known as Twitter), LinkedIn and Facebook.

Investor and Media Contacts:
Lindsey Manuel
lmanuel@ardelyx.com  

FAQ

What were the key findings of the ARDX OPTIMIZE Study for XPHOZAH?

The OPTIMIZE Study involved 330 CKD patients on dialysis, evaluating different methods of initiating XPHOZAH for phosphorus management in both binder-naïve and binder-treated patients. The post-hoc analysis showed improvements in stool frequency and consistency when used with antidiarrheal agents.

What is the FDA-approved indication for XPHOZAH (tenapanor)?

XPHOZAH is FDA-approved as an add-on therapy to reduce serum phosphorus in adult chronic kidney disease patients on dialysis who have inadequate response to phosphate binders or are intolerant to binder therapy.

How is XPHOZAH administered to patients with CKD?

XPHOZAH is administered as a single tablet taken twice daily, working through a unique mechanism of action that blocks phosphate absorption at the primary pathway.

When will Ardelyx present the XPHOZAH OPTIMIZE Study results?

Ardelyx will present the OPTIMIZE Study results at the National Kidney Foundation Spring Clinical Meetings from April 10-13, 2025, in Boston, with the poster presentation scheduled for April 10.