Study to Evaluate the Use of Tenapanor as Core Therapy in the Treatment of Hyperphosphatemia
Condition: Chronic Kidney Disease Requiring Chronic Dialysis; Hyperphosphatemia
MeSH terms: Kidney Diseases; Renal Insufficiency, Chronic; Hyperphosphatemia
Intervention: Tenapanor
Intervention description: Use of tenapanor
Phase: Phase 4
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Enrollment: 333.0
Sex: All
Minimum age: 18 Years
Maximum age: 90 Years
Healthy volunteers: No
Keywords: hyperphosphatemia

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.
    

Eligibility criteria:

        Inclusion Criteria:

          1. Signed and dated informed consent 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:

          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 investigational 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.