Ardelyx reported positive, topline results from the T3MPO-1 trial, the first of two Phase 3 trials evaluating tenapanor for the treatment of patients with irritable bowel syndrome with constipation (IBS-C). Tenapanor is Ardelyx's investigational, minimally systemic, small-molecule NHE3 inhibitor.

The T3MPO-1 trial achieved statistical significance for the primary endpoint and seven of eight secondary endpoints. The primary endpoint, the combined responder rate for six of 12 weeks, showed that a greater proportion of tenapanor-treated patients compared to placebo-treated patients (27.0% vs 18.7%, p=0.02) had at least a 30 percent reduction 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. Tenapanor was well-tolerated, consistent with the experience across previous clinical trials.

"We're pleased to have achieved the primary endpoint in the T3MPO-1 trial," Mike Raab, president and chief executive officer of Ardelyx said. "IBS-C is an extremely difficult, life-altering condition, and despite advancements, there remains a strong need for new, innovative treatments. In this trial, tenapanor demonstrated clinical activity across a large number of study parameters and had a favorable safety profile consistent with previous clinical experience. With a differentiated mechanism of action, we believe tenapanor has the potential to augment the care of patients with IBS-C."

T3MPO-1 was a 12-week, double-blind, placebo-controlled, multi-center, randomized trial with a four-week, randomized withdrawal period conducted in a total of 610 patients meeting the ROME III criteria for the diagnosis of IBS-C. Patients were randomized one to one to receive either 50 mg of tenapanor (n=309) or placebo (n=301) twice-daily. The trial included a two-week screening period, during which patients with active disease, based on bowel movement frequency and abdominal pain score recorded in a daily phone diary, were randomized into the trial.

Tenapanor was well-tolerated, consistent with the experience across previous clinical trials. The only adverse events observed in more than two percent of patients treated with tenapanor, as compared with placebo, were diarrhea (14.6% vs 1.7%) and nausea (2.6% vs 1.7%). Discontinuations due to diarrhea were 5.9 percent for the tenapanor-treated patients, compared to 0.6 percent for the placebo group, based on the preliminary results.

A second Phase 3 trial, T3MPO-2, a 26-week study evaluating tenapanor for the treatment of patients with IBS-C is ongoing with data expected early in the fourth quarter of 2017. Patients who have completed T3MPO-1 and T3MPO-2 are eligible to enter T3MPO-3, Ardelyx's open-label, long-term safety trial where patients can continue to receive tenapanor for up to one year. T3MPO-3 is expected to conclude in late 2017.