Tenapanor improves long-term control of high phosphate concentrations in the blood in patients receiving maintenance dialysis: a plain language summary of the NORMALIZE study

Plain Language Summary

What is this summary about?

This is a summary of an article that was published in the medical journal Kidney360 describing results from the NORMALIZE study. The NORMALIZE study looked at how well tenapanor tablets reduced higher-than-normal levels of phosphate in the blood of persons with kidney disease who are on maintenance dialysis. These persons are unable to keep their blood phosphate levels in a normal range, and high levels of phosphate can contribute to several serious health consequences.

Tenapanor is approved as an add-on treatment for high levels of phosphate in the blood of adults with chronic kidney disease who are on maintenance dialysis and whose disease does not respond adequately to treatment with phosphate binders or who are not able to take phosphate binders. In earlier clinical studies, tenapanor was studied alone or studied together with phosphate binders. In a 1-year clinical study called PHREEDOM, researchers learned that when tenapanor was used alone, it lowered blood phosphate levels, and treated patients experienced acceptable safety and tolerability as determined by the doctors running the study. In the NORMALIZE study, adult patients took a 30-mg tenapanor tablet twice a day, either alone or with sevelamer, for up to 18 months after they completed the PHREEDOM study.

What were the main conclusions reported by the researchers?

The researchers found that one-third of patients taking tenapanor, either alone or with sevelamer, achieved normal blood phosphate levels. This is an improvement from the current standard of care with sevelamer alone to reduce blood phosphate levels. As seen in the earlier studies of tenapanor, the most common adverse event experienced by patients was softer or loose stools. No new safety concerns were reported in the NORMALIZE study.

What are the key takeaways?

The researchers concluded that tenapanor, used alone or combined with sevelamer, can be used long-term by adult patients receiving maintenance dialysis to reduce the phosphate levels in their blood to within the normal range. Patients who take tenapanor may experience softer or loose stools.

This summary was developed by the authors to help adult patients with chronic kidney disease receiving dialysis, and their family members and/or caregivers, better understand the effects of taking tenapanor.

This is an abstract of the Plain Language Summary of Publication article.

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Acknowledgments

We would like to thank the patients and investigators who participated in the study. The NORMALIZE study has previously been presented at the World Congress of Nephrology (WCN) 2021 and the National Kidney Foundation (NKF) Spring Clinical Meeting 2022.

Author contributions

Conception and design: SE, YY. Analysis and interpretation of the data: GC, DR, AS, YY. Drafting and critical revision of the manuscript for intellectual content: All authors. Final approval: All authors.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Financial & competing interests disclosure

The authors had full control of this summary, and all authors agree to be accountable for all aspects of the work. In addition to the peer-review process, with the authors’ consent, the manufacturer of the product discussed in this article was given the opportunity to review the manuscript for factual accuracy. Changes were made by the authors at their discretion and based on scientific or editorial merit only. The authors maintained full control over the manuscript, including content, wording, and conclusions.

Writing disclosure

Medical writing support was provided by Katherine Cashell, BSc, from Ashfield MedComms (New York, NY, USA), an Inizio company, and was funded by Ardelyx Inc. (Waltham, MA, USA).

Data availability statement

Ardelyx will consider reasonable requests for data sharing such as the study protocol, SAP, and ICF on a case-by-case basis based on data availability, burden, and data privacy issues. This policy will go into effect immediately after publication for a period of up to 1 year. Data will be shared to achieve aims in an investigator-submitted proposal, which has been approved by Ardelyx. Proposals should be directed to [email protected]. To gain access to data, requestors will need to sign a data access agreement.

Ethics approval & consent to participate

The NORMALIZE study was conducted in accordance with the ethical principles of the Declaration of Helsinki and Good Clinical Practice guidelines. All patients provided written informed consent before study entry, and all participating sites obtained independent ethics committee/institutional review board approval.

Open access

This work is licensed under the Attribution-NonCommercial-NoDerivatives 4.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/. Copyright holder: The authors (Arnold L Silva, Glenn M Chertow, German T Hernandez, Robert I Lynn, David P Tietjen, David P Rosenbaum, Yang Yang, and Susan Edelstein).