Tenapanor improves symptoms in patients with IBS-C

Treatment with tenapanor improves symptoms in patients with irritable bowel syndrome with constipation (IBS-C) as early as week 1 of treatment, according to two phase III studies presented at DDW 2022.

The T3MPO-1* and T3MPO-2** cohorts consisted of 660 and 593 patients diagnosed with IBS-C, respectively. Participants were randomized to receive either tenapanor 50 mg (T3MPO-1: n=307, T3MPO-2: n=293) or placebo (T3MPO-1: n=299, T3MPO-2: n=300) twice daily for 12 weeks in T3MPO-1 and 26 weeks in T3MPO-2. Daily self-reported IBS symptoms and weekly IBS and constipation severity were assessed by using an IVRS*** diary. The primary endpoint of the study was the proportion of patients who achieved combined abdominal pain response (defined as ≥30 percent reduction in average weekly worst abdominal pain) and CSBM⁺ response (defined as ≥1 increase in weekly CSBM from baseline). [DDW 2022, abstract Tu1375]

As early as week 1, a significantly higher overall responder rate (combined abdominal pain and CSBM responses) was observed in the tenapanor group vs the placebo group in both the T3MPO-1 (15.8 percent vs 5.5 percent; p<0.001) and T3MPO-2 studies (20.5 percent vs 7.1 percent; p<0.001).

Patients treated with tenapanor also achieved a greater reduction in the average weekly abdominal pain scores compared with placebo in both studies (mean change from baseline, -13.8 percent vs -8.3 percent [T3MPO-1] and -16.0 percent vs -8.0 percent [T3MPO-2]).

Tenapanor recipients also experienced an increase in the average weekly CSBM (2.3 vs 0.7 [T3MPO-1] and 2.3 vs 0.6 [T3MPO-2]) and SBM frequency (5.0 vs 2.8 [T3MPO-1] and mean 6.4 vs 3.0 [T3MPO-2]).

In another analysis of T3MPO-1 and T3MPO-2 studies that evaluated the quality of life (QoL) of patients with IBS-C, more tenapanor-treated patients achieved a better QoL, as indicated by an overall IBS-QoL score of 80–100, than the placebo-treated patients at week 12 for T3MPO-1 (42.0 percent vs 36.0 percent) and week 26 for T3MPO-2 (49.0 percent vs 39.0 percent). [DDW 2022, abstract Mo1394]

In addition, more patients in both studies reported that they were “quite” or “very” satisfied with tenapanor than with placebo.

“Tenapanor provided statistically significant and clinically meaningful improvements in gastrointestinal and [abdominal] pain as early as the first week of treatment,” according to Dr Susan Edelstein from Ardelyx, Incorporated in Waltham, Maryland, US, who presented the study.

Building on the overall findings from the T3MPO-1 and T3MPO-2 studies, these data support tenapanor as a clinically meaningful treatment option for patients with IBS-C, providing not only symptom relief but improving QoL for some patients, they added.

*T3MPO-1: A 12-week study with a 4-week randomized withdrawal period to evaluate the efficacy and safety of tenapanor for the treatment of IBS-C

**T3MPO-2: A 26-week study to evaluate the efficacy and safety of tenapanor in IBS-C

***IVRS: Interactive voice response system

⁺CSBM: Complete spontaneous bowel movement