Ardelyx Plunges As Phase 2A Study Of Tenapanor Fails Primary Point

(RTTNews) - Ardelyx Inc (ARDX) on Tuesday said a Phase 2a trial of tenapanor in Stage 3 chronic kidney disease patients with type 2 diabetes mellitus and albuminuria did not meet the primary endpoint of reducing the urinary albumin-creatinine ratio in tenapanor-treated patients compared with those on placebo.

The study involved 154 patients who received tenapanor initially at 15 mg twice daily and had their dose escalated, stepwise, to 30 mg and 60 mg twice daily until they could no longer tolerate the gastrointestinal side effects (e.g., diarrhea), following which time the patient could elect to down-titrate the dose in a stepwise manner to as low as 5 mg twice daily.

The study did not meet the primary endpoint of a statistically significant decrease of urinary albumin-creatinine ratio from baseline to week 12 for tenapanor-treated patients compared to patients receiving placebo with a 16% reduction in the tenapanor group versus 11% on placebo.

About one-third of those patients treated with tenapanor had no incidence of diarrhea. No significant effect was observed on mean systolic or diastolic blood pressure or eGFR, and no significant effect was detected on mean urinary sodium excretion, the company said.

The overall safety profile remains consistent with that observed in previous tenapanor trials, with no significant differences observed between placebo and tenapanor, except with respect to diarrhea and loose stools.

Ardelyx formed a partnership with AstraZeneca in October 2012 to develop and commercialize Tenapanor, which has been evaluated in a number of trials in in healthy volunteers and in patients with constipation-predominant irritable bowel syndrome (IBS-C), hyperphosphatemia and chronic kidney disease (CKD).

With the completion of the CKD trial, Ardelyx and AstraZeneca are assessing the data from all the trials. Under the terms of the agreement, AstraZeneca is obligated to communicate to Ardelyx, on or before June 29, whether it will continue the development of tenapanor.

Should AstraZeneca decide to pursue the development of only the IBS-C indication, Ardelyx will be entitled to a milestone payment of $10 million. Should AstraZeneca decide to pursue the development of any other indication or multiple indications, Ardelyx will be entitled to receive a $20 million milestone payment.

"We continue to work with AstraZeneca as they evaluate the data, and we are preparing for the continuation of the development of tenapanor under a variety of different scenarios," said Ardelyx CEO Mike Raab.

"We are preparing for an end of phase 2 meeting for IBS-C with the FDA scheduled to occur in June. Should AstraZeneca decide to return the program to us, we seek to be in a position to initiate a Phase 3 clinical program for tenapanor in IBS-C in the fourth quarter of 2015. Additionally, we intend to be prepared to continue the development of tenapanor for the treatment of hyperphosphatemia in CKD patients on dialysis."

ARDX closed Tuesday at $10.91, down $0.05 or 0.46%, on the Nasdaq. In after hours, the stock dropped $2.81 or 25.76% at $8.10.