Assessing Tenapanor as a Treatment of CF-related Constipation.

An Open-label, Single Center Study Assessing Tenapanor as a Non-CFTR-mediated Treatment of CF-related Constipation in People With CF.

Tenapanor is the newest FDA-approved drug for IBS with constipation (IBS-C). This study seeks to understand tenapanor as a treatment for cystic fibrosis-related constipation (CFrC) in CF patients. Participants will ingest one 50 mg tablet of tenapanor, twice daily, for a 4-week treatment period. They will also complete three questionnaires, the PAC-SYM, PAC-QoL, and IBS-SSS, and daily diaries to characterize GI symptom burden and spontaneous bowel movement (SBM) frequency.

Study Overview

• Status: Recruiting
• Conditions: Constipation; Cystic Fibrosis
• Intervention / Treatment: Drug: Tenapanor

• Study Type: Interventional
• Enrollment (Estimated): 25
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Chloe Butzel, BA; Phone Number: 6176437088; Email: cbutzel@mgh.harvard.edu

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02114
      • Recruiting
      • Massachusetts General Hospital
      • Contact: Chloe Butzel, BA; Phone Number: 6176437088; Email: cbutzel@mgh.harvard.edu
      • Principal Investigator: Christopher Velez, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Having confirmed cystic fibrosis (either by sweat chloride or genetic testing)

2. Meeting criteria for CFrC

   Must include 2 of the following, with or without abdominal pain for at least 3 months, with symptom onset at least 6-months prior:

   • Straining in at least 25% of defecations
   • Bristol Stool Scale 1-2 more than 25% of defecations (change in stool form)
   • Sensation of incomplete evacuation more than 25% of defecations
   • Sensation of anorectal obstruction/blockage more than 25% of defecations
   • Manual disimpaction/manipulation of pelvic floor to facilitate more than 25% of defecations
   • Fewer than 3 spontaneous bowel movements weekly (change in stool frequency)
   • Loose stools rarely present without the use of laxatives
3. Willingness to avoid major dietary or lifestyle changes during study.

Exclusion Criteria:

1. Use of any antibiotic to treat infection within the 4-weeks prior to study initiation (stable azithromycin dosed 3-times weekly for lung function is to be allowed)
2. Inability to discontinue standing bowel regimen (including fiber, stool softener, as well as either osmotic or stimulant laxative, pro-kinetic serotonergic agents, or other therapy) 2-weeks prior to study drug initiation (with ability to use osmotic laxative therapy as rescue therapy only).
3. Severe CFrC as determined by study team
4. Prior tenapanor usage
5. Hospitalization within 4-weeks prior to study initiation.
6. DIOS within 4-weeks prior to study initiation.
7. Other known/suspected mechanical obstruction

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: Cystic fibrosis patients with CF-related constipation	Drug: Tenapanor; CF patients with CFrC will ingest one 50 mg tablet of tenapanor twice daily for 4 weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Increase in SBM frequency	There will be a statistically significant increase in spontaneous bowel movement frequency (SBM) in cystic fibrosis patients with CF-related constipation receiving tenapanor.	Patients will record SBM frequency over the 4-week treatment period.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in PAC-SYM questionnaire score	There will be a change (with use of descriptive statistics) in bowel symptoms characterized by the Patient Assessment of Constipation Symptoms (PAC-SYM) questionnaire with tenapanor administration. PAC-SYM is a PRO previously used to examine constipation in pwCF. A decreased score corresponds to improvement of bowel symptoms.	Patients will complete the PAC-SYM at -2 weeks, 0 weeks, 2 weeks, and 4 weeks.
Change in PAC-QOL questionnaire score	There will be a change (with use of descriptive statistics) in bowel symptoms characterized by the Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaire with tenapanor administration. PAC-QOL is a PRO previously used to examine constipation in pwCF. A decreased score corresponds to improvement of bowel symptoms.	Patients will complete the PAC-QOL at -2 weeks, 0 weeks, 2 weeks, and 4 weeks.
Change in IBS-SSS questionnaire score	There will be a 50-point change in the Irritable Bowel Syndrome Scoring System - IBS-SSS (in line with recent bowel distress related literature Ford AC, Wright-Hughes A, Alderson SLet al Lancet 2023) in pwCF and CFrC receiving tenapanor.	Patients will complete the IBS-SSS at -2 weeks, 0 weeks, 2 weeks, and 4 weeks.

Collaborators and Investigators

• Sponsor: Massachusetts General Hospital
• Collaborators: Ardelyx
• Investigators: Principal Investigator: Christoher D Velez, MD, Massachusetts General Hospital

Study record dates

Study Major Dates

• Study Start (Actual): June 1, 2025
• Primary Completion (Estimated): June 30, 2026
• Study Completion (Estimated): June 30, 2027

Study Registration Dates

• First Submitted: January 23, 2025
• First Submitted That Met QC Criteria: January 31, 2025
• First Posted (Actual): February 5, 2025

Study Record Updates

• Last Update Posted (Actual): March 18, 2026
• Last Update Submitted That Met QC Criteria: March 17, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Constipation; Cystic Fibrosis; CFrC
• Additional Relevant MeSH Terms: Genetic Diseases, Inborn; Signs and Symptoms, Digestive; Respiratory Tract Diseases; Digestive System Diseases; Lung Diseases; Infant, Newborn, Diseases; Pancreatic Diseases; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Constipation; Cystic Fibrosis; tenapanor
• Other Study ID Numbers: 2024P002058

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