Ardelyx’s tenapanor shows significant effect in hyperphosphatemia in phase 3 trial

Tenapanor works by blocking the NHE3 sodium transporter in the gastrointestinal (GI) tract, reducing the absorption of dietary sodium resulting in increased protons within the cells.

In the Phase 3 study, Ardelyx enrolled a total of 219 ESRD patients with hyperphosphatemia who are on dialysis and randomized evenly into three arms to receive tenapanor for eight weeks.

The trial showed notable difference in serum phosphorus from baseline to the end of the eight-week treatment period of 2.56 mg/dL, with a reduction of up to 5.7 mg/dL.

According to the firm, the study demonstrated a statistically significant difference in serum phosphorus levels from the end of the eight-week treatment period to the end of the four-week randomized withdrawal period between the tenapanor-treated group and the placebo-treated group in the responder patient population.

With a four-week placebo-controlled randomized withdrawal period, the Phase III study was an eight-week, double-blind and randomized study.

Based on the current results, the company is planning to start the second phase III study of tenapanor to treat hyperphosphatemia in ESRD patients on dialysis in the middle of this year.

The phase III trial will comprise of 26-week open-label treatment period with a randomized withdrawal period followed by an additional 26-week long-term safety extension.

Currently, the firm is under consultation with advisors for the final trial design, and will disclose the details upon initiation of the study.

Ardelyx president and CEO Mike Raab said: “The magnitude of the reduction of serum phosphorus in a large percentage of patients treated with tenapanor in this trial surpassed our expectations.”

Image: Ardelyx has met its primary endpoint in the trial of experimental medication tenapanor to treat hyperphosphatemia in patients with ESRD. Photo: courtesy of Ardelyx.