Ardelyx reports positive results in second Phase III trial of experimental IBS-C drug tenapanor

Shares in Ardelyx jumped as much as over 60 percent Wednesday after the company said a Phase III study of tenapanor in patients suffering from irritable bowel syndrome with constipation (IBS-C) reached its primary endpoint and all secondary goals. Based on data from the T3MPO-2 trial, as well as positive results from the previously announced Phase III T3MPO-1 study, Ardelyx anticipates filing the experimental NHE3 inhibitor for US approval in the second half of 2018 as a potential treatment for IBS-C. 

In the 26-week study, 593 patients meeting the ROME III criteria for the diagnosis of IBS-C were randomised to treatment with tenapanor or placebo. The primary endpoint was the combined responder rate, defined as a reduction of at least 30 percent in abdominal pain and an increase of one or more complete spontaneous bowel movements (CSBM) in the same week for at least six of the 12 weeks of the treatment period. Secondary endpoints included the CSBM and abdominal pain responder rates for six or nine weeks of the 12-week treatment period. 

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Results from the study showed that 36.5 percent of patients in the tenapanor group met the primary endpoint, versus 23.7 percent of those in the placebo arm. Further, Ardelyx noted that tenapanor achieved statistical significance for the CSBM and abdominal pain responder rates for six and nine weeks, "with a consistent response across the 26 weeks of the study," and was also well-tolerated in treated patients. The company added that detailed results will be submitted for presentation at a research conference next year. 

CEO Mike Raab said the T3MPO-2 data "are a game-changer for patients with IBS-C, their treating physicians and for Ardelyx as a company." He added that the results "demonstrate the significant benefit tenapanor can have for patients with IBS-C, importantly, leading to a normalisation of bowel movements for many patients."

In 2015, Ardelyx reported that tenapanor, which it was co-developing with AstraZeneca, had failed a mid-stage study of chronic kidney disease patients with type 2 diabetes mellitus and albuminuria. The companies later terminated their partnership, with Ardelyx regaining rights to its portfolio of NHE3 inhibitors, including tenapanor.

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