Ardelyx has reported that long-term 52-week data from the Phase III PHREEDOM trial showed tenapanor monotherapy provided a clinically meaningful decline in mean serum phosphorus in chronic kidney disease (CKD) patients on dialysis.

Tenapanor has a peculiar mechanism of action and works locally in the gut to hinder the sodium hydrogen exchanger 3 (NHE3). It reduces phosphate absorption through the paracellular pathway, which is the key pathway of phosphate absorption.

This new obstruction mechanism facilitates a 30mg tablet twice-daily dosing regimen, the company noted.

The 52-week randomised Phase III PHREEDOM trial analysed tenapanor as a monotherapy in treating hyperphosphatemia or controlling serum phosphorus in CKD patients on dialysis.

According to the latest data, tenapanor treatment offered a clinically meaningful drop in mean serum phosphorus from 7.7mg/dL at baseline to 5.1mg/dL at the end of the 26-week therapy period in the efficacy analysis set.

In the intent-to-treat analysis set, the drug provided a clinically meaningful decline in mean serum phosphorus from 7.4mg/dL at baseline to 5.9mg/dL at week 26.

Furthermore, the change in expected mean change in serum phosphorus level between tenapanor and placebo for the randomised withdrawal period was −1.4 mg/dl in the efficacy analysis set.

At the end of the randomised 26-week therapy period for subjects receiving tenapanor, median relative reductions from baseline were 23% and 14% for iFGF23 and cFGF23, respectively.

The company noted diarrhoea was the only treatment-related adverse event observed in more than 5% of the subjects.

Ardelyx president and CEO Mike Raab said: “The PHREEDOM data demonstrate the ability of tenapanor to provide significant phosphorus reduction with long-term safety comparable to active control.

“This study, together with data from our AMPLIFY trial, which evaluated tenapanor in combination with binders in patients who require more aggressive phosphate management, supports the central role tenapanor, with its novel blocking mechanism, can play across a broad range of patients and treatment regimens for the management of hyperphosphatemia in patients with chronic kidney disease on dialysis.”

In 2019, Ardelyx and Kyowa Kirin expanded their collaboration for the former’s novel cardiorenal-focused therapies.