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CompletedNCT04549597OPTIMIZEUpdated Mar 29, 2023Results posted

Study to Evaluate the Use of Tenapanor as Core Therapy in the Treatment of Hyperphosphatemia

A Phase 4 interventional study of Tenapanor in Chronic Kidney Disease Requiring Chronic Dialysis and Hyperphosphatemia, sponsored by Ardelyx. Completed at 1 site in United States. Open to participants aged 18 Years to 90 Years. Per ClinicalTrials.gov, last updated 2023-03-29.

Sponsored by Ardelyx · Phase 4, Interventional, and Treatment

Phase
Phase 4
Study type
Interventional
Enrollment
333
Allocation
Randomized
Ages
18 Years to 90 Years
Sex
All
01

Study summary

This is a randomized, open-label study to evaluate different methods of initiating tenapanor therapy in CKD patients on dialysis with hyperphosphatemia, when they are either phosphate binder naïve or on phosphate binder therapy. The objective to evaluate the effect of tenapanor alone or in combination with phosphate binders to achieve target serum phosphorus (s-P) levels of ≤5.5 mg/dL when tenapanor is administered as the core therapy (alone or in combination with phosphate binders) for the treatment of hyperphosphatemia in patients with chronic kidney disease (CKD) on dialysis.

Read the detailed description

Approximately 330 CKD patients on dialysis with hyperphosphatemia (>4.5 mg/dL) will be enrolled in this study.

This is a randomized, open-label study to evaluate different methods of initiating tenapanor therapy in CKD patients on dialysis with hyperphosphatemia, when they are either phosphate binder naïve or on phosphate binder therapy.

The study consists of a Screening visit and a 10-week open-label Treatment Period (TP), for which

  • Patients with s-P >5.5 and ≤10.0 mg/dL under stable phosphate binder treatment are randomized in a 1:1 ratio to two different treatment cohorts:

    • Cohort 1 (straight switch), which stops taking phosphate binders and is started on tenapanor 30 mg twice daily (BID) at Visit 2 (Day 1);
    • Cohort 2, which decreases phosphate binder dose by at least 50% (may be more than 50% if patient is taking an odd number of binder pills each day), with ability to switch the binder regimen from thrice daily (TID) to BID or QD; and initiates tenapanor 30 mg BID at Visit 2 (Day 1).
  • Phosphate binder naïve patients with s-P >4.5 and ≤10.0 mg/dL are enrolled as Cohort 3 and receive tenapanor at Visit 2 (Day 1) with a starting dose of 30 mg BID.
  • Patients on phosphate binder therapy must receive phosphate binder(s) thrice daily, and both the s-P level assessed at the most recent measurement prior to the Screening visit (Visit 1) and the s-P level assessed at the Screening visit (Visit 1) must be >5.5 and ≤10.0 mg/dL to qualify for randomization into Cohort 1 or Cohort 2 at Visit 2 (Day 1).
  • Phosphate binder naïve patients must have the s-P level assessed at the Screening visit (Visit 1) >4.5 and ≤10.0 mg/dL to qualify for enrollment into Cohort 3 at Visit 2 (Day 1).

Patients who do not meet the randomization/enrollment criteria on s-P will be discontinued as screen failures.

During the TP, patients will receive tenapanor starting at a dose of 30 mg twice daily. Tenapanor will be taken twice daily; just prior to breakfast and dinner. The Investigator may titrate the dose of tenapanor in 10 mg increments down to a minimum of 10 mg QD or up to a maximum of 30 mg BID at any time during the study based on s-P levels and/or gastrointestinal (GI) tolerability.

02

Conditions studied

  • Chronic Kidney Disease Requiring Chronic Dialysis
  • Hyperphosphatemia

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Keywords

  • hyperphosphatemia
03

In context

Hyperphosphatemia

173 studies on the registry are indexed under Hyperphosphatemia; 16 are open to participants now.

This study's enrollment of 333 is above the median of 101 across 143 interventional studies indexed under Hyperphosphatemia.

Browse Hyperphosphatemia studies →

Lead sponsor

Ardelyx is the lead sponsor of 29 studies on the registry; 2 are open to participants now.

Of its 8 completed or terminated interventional studies of FDA-regulated products, 4 (50%) have results posted.

Browse Ardelyx studies →

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years to 90 Years
Sexes eligible
All
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  1. Signed and dated form prior to any study specific procedures.
  2. Males or females aged 18 to 80 years, inclusive, at Screening (Visit 1).
  3. Females must be non-pregnant and non-lactating.
  4. Patients on phosphate binder therapy must be on chronic maintenance hemodialysis (HD) 3 times per week for at least 3 months or chronic maintenance peritoneal dialysis (PD) for a minimum of 6 months. If modality of dialysis has changed, the patient must meet one of the two dialysis criteria above and been on the new modality of dialysis for a minimum of one month. Phosphate binder naïve patients must be on chronic maintenance HD 3 times per week or chronic maintenance PD.
  5. Kt/V ≥1.2 at most recent measurement prior to Screening (Visit 1).
  6. Prescribed and taking phosphate binder medication at least 3 times per day or being phosphate binder naïve; defined as having not taken phosphate binders for at least 3 months prior to Screening. The patient must be taking a minimum of 6 pills per day for Renvela, Auryxia, or PhosLo; and/or a minimum of 3 pills per day for Fosrenol or Velphoro.
  7. For patients taking phosphate binders, both the s-P level at the most recent measurement prior to Screening (Visit 1) and the s-P level at Screening (Visit 1) must be >5.5 and ≤10.0 mg/dL.
  8. For phosphate binder naïve patients, the s-P level at Screening (Visit 1) must be >4.5 and ≤10.0 mg/dL.
  9. Able to understand and comply with the protocol.

Exclusion criteria

Exclusion Criteria:

  1. Severe hyperphosphatemia defined as having an s-P level >10.0 mg/dL at any time point during routine clinical monitoring for the 3 preceding months before Screening (Visit 1).
  2. Serum/plasma PTH >1200 pg/mL. The most recent value from the patient's medical records should be used.
  3. Clinical signs of hypovolemia at Screening (Visit 1) as judged by the Investigator.
  4. History of inflammatory bowel disease or irritable bowel syndrome with diarrhea.
  5. Scheduled for living donor kidney transplant or plans to relocate to another center during the study.
  6. Use of an agent within 30 days prior to Screening (Visit 1).
  7. Involvement in the planning and/or conduct of the study (applies to both Ardelyx/Contract Research Organization (CRO) staff and/or staff at the study site).
  8. If, in the opinion of the Investigator, the patient is unable or unwilling to fulfill the requirements of the protocol or has a condition which would render the results uninterpretable.
Terms in these criteria, in plain language(2)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

05

Study design

Phase
Phase 4
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
333 participants (actual)

Study arms

  • Experimental
    Cohort 1: Straight Switch

    Patients stop taking phosphate binders and start tenapanor 30 mg twice daily

    Drug: Tenapanor

  • Experimental
    Cohort 2: Decrease Phosphate Binder by 50%

    Decreases phosphate binder dose by at least 50% with the ability to switch the binder regiment from thrice daily (TID) to BID or once a day and initiates tenapanor 30 mg BID

    Drug: Tenapanor

  • Experimental
    Cohort 3: Phosphate Binder Naive

    Phosphate binder naive patients are enrolled as Cohort 3 and receive tenapanor with a starting dose of 30 mg/BID

    Drug: Tenapanor

Interventions

06

What researchers measure

Primary outcomes

  1. Effect of Tenapanor to Achieve Target s-P Levels of Less Than or Equal to 5.5 mg/dL

    To evaluate the effect of tenapanor alone or in combination with phosphate binders to achieve target serum phosphorus (s-P) levels of ≤5.5 mg/dL when tenapanor is administered as the core therapy for the treatment of hyperphosphatemia in patients with chronic kidney disease (CKD) on dialysis.

    Time frame: 10 weeks

Secondary outcomes

  1. To Evaluate the Effect of Tenapanor to Achieve Various s-P Levels ≤4.5 mg/dL

    Evaluating the ability of different treatment regimens to lower s-P to different levels

    Time frame: 10 weeks

  2. To Evaluate the Effect of Tenapanor on Reducing Daily Phosphorus-lowering Therapy Pill Burden.

    Evaluating the ability of tenapanor to make the phosphate lowering treatment regimen better for patients by evaluating the change in pill weight or pill number from baseline to the end of the 10-week treatment period.

    Time frame: 10 weeks

07

Results

Posted Mar 29, 2023
Limitations and caveats
This was an open label study

Participant flow

Participant flow — Overall Study
MilestoneCohort 1 (Straight Switch)Cohort 2 (50% Phosphate Binder Reduction)Cohort 3: Phosphate Binder Naive
Started15115230
Completed12713325
Not completed24195

Outcome measures

PrimaryEffect of Tenapanor to Achieve Target s-P Levels of Less Than or Equal to 5.5 mg/dL

To evaluate the effect of tenapanor alone or in combination with phosphate binders to achieve target serum phosphorus (s-P) levels of ≤5.5 mg/dL when tenapanor is administered as the core therapy for the treatment of hyperphosphatemia in patients with chronic kidney disease (CKD) on dialysis.

Time frame:
10 weeks
Reported as:
Count of participants · Participants
Effect of Tenapanor to Achieve Target s-P Levels of Less Than or Equal to 5.5 mg/dL
ParticipantsCohort 1: Straight SwitchCohort 2: Decrease Phosphate Binder by 50%Cohort 3: Phosphate Binder Naive
Effect of Tenapanor to Achieve Target s-P Levels of Less Than or Equal to 5.5 mg/dL525819
SecondaryTo Evaluate the Effect of Tenapanor to Achieve Various s-P Levels ≤4.5 mg/dL

Evaluating the ability of different treatment regimens to lower s-P to different levels

Time frame:
10 weeks
Reported as:
Count of participants · Participants
To Evaluate the Effect of Tenapanor to Achieve Various s-P Levels ≤4.5 mg/dL
ParticipantsCohort 1: Straight SwitchCohort 2: Decrease Phosphate Binder by 50%Cohort 3: Phosphate Binder Naive
To Evaluate the Effect of Tenapanor to Achieve Various s-P Levels ≤4.5 mg/dL182313
SecondaryTo Evaluate the Effect of Tenapanor on Reducing Daily Phosphorus-lowering Therapy Pill Burden.

Evaluating the ability of tenapanor to make the phosphate lowering treatment regimen better for patients by evaluating the change in pill weight or pill number from baseline to the end of the 10-week treatment period.

Time frame:
10 weeks
Reported as:
Median · mg
To Evaluate the Effect of Tenapanor on Reducing Daily Phosphorus-lowering Therapy Pill Burden.
mgCohort 1: Straight SwitchCohort 2: Decrease Phosphate Binder by 50%Cohort 3: Phosphate Binder Naive
To Evaluate the Effect of Tenapanor on Reducing Daily Phosphorus-lowering Therapy Pill Burden.-6262 ± 6149.7-3290 ± 5263.4—

Adverse events

Collected over 10 week treatment period followed by optional 16 week extension period. Non-serious events are listed at a 5% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
Cohort 11/151 (0.7%)20/151 (13.2%)59/151 (39.1%)
Cohort 21/152 (0.7%)26/152 (17.1%)64/152 (42.1%)
Cohort 3: Phosphate Binder Naïve0/30 (0%)4/30 (13.3%)10/30 (33.3%)
Most frequent serious events
Showing 10 of 18
Most frequent serious events
EventCohort 1Cohort 2Cohort 3: Phosphate Binder Naïve
HyperkalemiaMetabolism and nutrition disorders3/1512/1521/30
Acute Myocardial InfarctionCardiac disorders3/1510/1521/30
Fluid OverloadCardiac disorders1/1512/1521/30
SepsisInfections and infestations2/1510/1521/30
Covid-19Infections and infestations2/1515/1520/30
PneumoniaRespiratory, thoracic and mediastinal disorders2/1514/1520/30
PeritonitisInfections and infestations0/1513/1520/30
Diabetic FootSkin and subcutaneous tissue disorders2/1510/1520/30
Chest PainCardiac disorders1/1512/1520/30
NauseaGastrointestinal disorders0/1512/1520/30
Most frequent other events
Most frequent other events
EventCohort 1Cohort 2Cohort 3: Phosphate Binder Naïve
DiarrheaGastrointestinal disorders59/15164/15210/30

Baseline characteristics

Age, Continuous
Age, Continuous(years)Cohort 1Cohort 2Cohort 3: Phosphate Binder NaïveTotal
Mean52.3 ± 11.0553.3 ± 12.1655.4 ± 16.5253.0 ± 12.13
Sex: Female, Male
Sex: Female, Male(Participants)Cohort 1Cohort 2Cohort 3: Phosphate Binder NaïveTotal
Female445012106
Male10710218227
Ethnicity (NIH/OMB)
Ethnicity (NIH/OMB)(Participants)Cohort 1Cohort 2Cohort 3: Phosphate Binder NaïveTotal
Hispanic or Latino42381393
Not Hispanic or Latino10911417240
Unknown or Not Reported0000
Race (NIH/OMB)
Race (NIH/OMB)(Participants)Cohort 1Cohort 2Cohort 3: Phosphate Binder NaïveTotal
American Indian or Alaska Native36110
Asian133016
Native Hawaiian or Other Pacific Islander2406
Black or African American66719146
White646220146
More than one race2406
Unknown or Not Reported1203
08

Study locations

1 site
  • South Florida Research Institute
    Lauderdale Lakes, Florida 33313, United States
09

References and documents

Study documents

PDFs hosted by the registry, ClinicalTrials.gov.

Individual participant data

Plan to share: No

10

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Mar 29, 2023, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
11

Registry details

Key details

Study ID
NCT04549597
Lead sponsor
Ardelyx
Responsible party
Sponsor
First posted
Sep 16, 2020
Start date
Nov 20, 2020
Primary completion
Oct 13, 2021
Completion
Dec 1, 2021
Results posted
Mar 29, 2023
Last update
Mar 29, 2023

Oversight

Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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