Ardelyx has confirmed that its NHE3 inhibitor tenapanor met all its primary and secondary endpoints in the study of its treatment efficacy against irritable bowel syndrome and constipation (IBS-C). Based on the positive results the therapy has garnered, Ardelyx plans to file for US approval of the drug in the second half of 2018.

The latest study lasted for 26 weeks and comprised 593 participants, where combined responder rate was the primary endpoint, defined as a reduction of at least 30% 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 were defined as responder rates for CSBM and abdominal pain for six or nine weeks of this 12-month period.  

Based on these goals, 36.5% of patients taking tenapanor achieved the primary endpoint compared to only 23.7% of those taking placebo. The company noted a consistent response across the full duration of the study, with the treatment achieving "statistical significance" in meeting its secondary endpoints. The drug was well tolerated by participants of the study.

Ardelyx CEO Mike Raab called the results "a game-changer for patients with IBS-C, their treating physicians and for Ardelyx as a company", due to the "significant benefit tenapanor can have for patients with IBS-C, importantly, leading to a normalisation of bowel movements for many patients."

The news was very well received in the stock market, with Ardelyx’s shares shooting up by 60% as a result.