Abdominal Symptom Improvement During Clinical Trials of Tenapanor in Patients With Irritable Bowel Syndrome With Constipation: A Post Hoc Analysis

Am J Gastroenterol. 2024 Jan 31. doi: 10.14309/ajg.0000000000002685. Online ahead of print.


Anthony J Lembo 1William D Chey 2Lucinda A Harris 3Rosita Frazier 3Darren M Brenner 4Lin Chang 5Brian E Lacy 6Susan Edelstein 7Yang Yang 7Suling Zhao 7David P Rosenbaum 7


Author information

1Digestive Disease Institute, Cleveland Clinic, Cleveland, Ohio, USA.

2Division of Gastroenterology, Department of Medicine, University of Michigan Health System, Ann Arbor, Michigan, USA.

3Mayo Clinic, Alix School of Medicine, Division of Gastroenterology & Hepatology, Scottsdale, Arizona, USA.

4Division of Gastroenterology and Hepatology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.

5Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California.

6Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, Florida, USA.

7Ardelyx, Inc., Waltham, Massachusetts, USA.


Objectives: This post hoc analysis evaluated the efficacy of tenapanor on abdominal symptoms in patients with irritable bowel syndrome with constipation (IBS-C). Abdominal symptoms assessed included pain, discomfort, bloating, cramping, and fullness.

Methods: The abdominal symptom data were pooled from 3 randomized controlled trials (NCT01923428, T3MPO-1 [NCT02621892], and T3MPO-2 [NCT02686138]). Weekly scores were calculated for each abdominal symptom, and the Abdominal Score (AS) was derived as the average of weekly scores for abdominal pain, discomfort, and bloating. The overall change from baseline during the 12 weeks was assessed for each symptom weekly score and the AS. The AS 6/12-week and 9/12-week response rates (AS improvement of ≥2 points for ≥6/12- or ≥9/12-week) were also evaluated. The association of weekly AS response status (reduction of ≥30%) with weekly complete spontaneous bowel movement (CSBM) status (=0 and >0) was assessed.

Results: Among 1,372 patients (684 tenapanor [50 mg twice a day] and 688 placebo), the least-squares mean change from baseline in AS was -2.66 for tenapanor vs -2.09 for placebo (P<0.0001). The 6/12-week AS response rate was 44.4% for tenapanor vs 32.4% for placebo (P<0.0001), and for 9/12-week AS, 30.6% for tenapanor vs 20.5% for placebo (P<0.0001). A significant association between weekly CSBM status and weekly AS response status was observed each week (P<0.0001), with a greater proportion achieving an AS reduction in patients with >0 CSBMs in a week.

Conclusion: Tenapanor significantly reduced abdominal symptoms in patients with IBS-C, particularly pain, discomfort, and bloating measured by AS, compared with placebo.

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