Dietary Intervention in ADPKD on Tolvaptan (DIAT)

Dietary Intervention in Patients With ADPKD on Tolvaptan: Urine Output and Quality of Life

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited renal disorder. Tolvaptan has been approved in Canada as a treatment for ADPKD. Tolvaptan is an arginine vasopressin receptor antagonist which has been shown to decrease the progression of ADPKD. The main side effect of this treatment is increased urine output which leads to cessation of therapy in about 20% of patients. Low solute (low sodium, low protein) diet may alleviate this side effect. This is a single arm before / after study of dietary intervention on urine output and quality of life in ADPKD patients on a stable dose of tolvaptan.

Study Overview

• Status: Completed
• Conditions: Polyuria; Autosomal Dominant Polycystic Kidney
• Intervention / Treatment: Other: Dietary

Detailed Description

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited renal disorder affecting 12.5 million persons worldwide, and impacting approximately 35,000-66,000 Canadians. An estimated 45% to 70% of patients with ADPKD progress to end-stage renal disease by age 65 years.

Tolvaptan has been approved in Canada as a treatment for ADPKD. Tolvaptan was discovered in Japan by Otsuka Pharmaceutical and was first approved there for ADPKD in 2014. The Health Canada approval of Tolvaptan is based on the results of the pivotal Phase 3 randomized, double-blind and placebo-controlled TEMPO 3:4 Trial, the largest study conducted to date in adults with ADPKD.

The treatment of ADPKD had previously been symptomatic with the aim of reducing morbidity and mortality associated with disease manifestations. This changed with the publication of the TEMPO 3:4 trial, which proved the efficacy of the arginine vasopressin (AVP) V2 receptor antagonist tolvaptan in decreasing the progression of CKD. In this trial, 1445 patients with ADPKD eGFR > 60 were randomized to receive either placebo or tolvaptan in a split-dose regimen of 45 mg in the morning and 15 mg in the afternoon, up titrated to 90/30 mg as tolerated. The REPRISE study investigated the value of tolvaptan in 1300 patients with lower levels of eGFR (25-65 mL/min/1.73 m2).

AVP plays a major role in the pathogenesis of cysts in ADPKD via cAMP stimulation. The AVP antagonist blocks V2 receptors in collecting ducts and therefore blocks the concentrating ability of the tubule. This leads to increased urine volume. Recently, it has been demonstrated that this increased urine volume is related to solute excretion. Therefore, it seems possible that dietary modification to decrease solute intake (salt, protein) would decrease the urine volume in patients taking tolvaptan.

The most common side effect of AVP antagonist is increased renal water excretion which presents as polyuria, nocturia, increased thirst, and dry mouth. The daily urine volumes 5 days after starting different split doses of tolvaptan (15/15, 30/0, 30/15, 30/30 mg) in a preliminary phase 2 study were 4 to 6 L. In the treatment of hyponatremia and heart failure (another indication for tolvaptan therapy), a meta-analysis found an average increase in water clearance of only 68 mL/h after tolvaptan treatment. This more modest increase in urine output may be related to the low sodium diet most of these patients should be adhering to.

• Study Type: Interventional
• Enrollment (Actual): 8
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Peter Margetts, MD PhD; Phone Number: 32299 9055221155; Email: margetts@mcmaster.ca

Study Locations

• Canada
  • Ontario
    • Hamilton, Ontario, Canada, L8N 4A6
      • St. Joseph's Healthcare

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Patients seen in the Hamilton Nephrology Genetics Clinic with a diagnosis of ADPKD taking tolvaptan
2. Able to provide informed consent
3. On maximal tolerated dose of tolvaptan for at least 3 months

Exclusion Criteria:

1. Serum sodium > 135 mmol/L
2. Patients with evidence of non-compliance (not completing monthly blood work required while on tolvaptan therapy).
3. Unlikely to continue in Hamilton Nephrology Genetics Clinic for at least 6 months (planned dialysis initiation, transplant)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intervention; Single arm study. All participants will receive dietary intervention.	Other: Dietary; Low sodium, low protein dietary recommendation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in 24-hour urine volume	24-hour urine volume in ml.	Change from baseline to 3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in ADPKD-IS	Autosomal dominant polycystic kidney disease impact score - quality of life. Eighteen items, score from 18 to 90 with higher values reflecting lower quality of life	Change from baseline to 3 months
Change in Nagasaki Diabetes Insipidus Questionnaire	Validated measure of polyuria on quality of life. Subset of questions 1-10 will be used (Questions 11-12 relate to therapy with DDAVP). Score from 10 to 40 with higher scores reflecting worse quality of life.	Change from baseline to 3 months
Change in urine total solute	Urine total solute measured by (urine sodium + urine urea) * urine volume	Change from baseline to 3 months

Collaborators and Investigators

• Sponsor: McMaster University

Study record dates

Study Major Dates

• Study Start (Actual): June 6, 2019
• Primary Completion (Actual): September 24, 2021
• Study Completion (Actual): May 16, 2022

Study Registration Dates

• First Submitted: February 4, 2019
• First Submitted That Met QC Criteria: February 27, 2019
• First Posted (Actual): February 28, 2019

Study Record Updates

• Last Update Posted (Actual): March 15, 2024
• Last Update Submitted That Met QC Criteria: March 13, 2024
• Last Verified: March 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Kidney Diseases; Urologic Diseases; Urological Manifestations; Congenital Abnormalities; Genetic Diseases, Inborn; Urination Disorders; Abnormalities, Multiple; Kidney Diseases, Cystic; Ciliopathies; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Male Urogenital Diseases; Polycystic Kidney Diseases; Polycystic Kidney, Autosomal Dominant; Polyuria
• Other Study ID Numbers: v1

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No