FDA Extends PDUFA Date on Tenapanor

The US Food and Drug Administration (FDA) has extended the Prescription Drug User Fee Act (PDUFA) date for tenapanor, a potential treatment for the control of serum phosphorus in adult patients with chronic kidney disease (CKD) on dialysis for an additional 3 months.

The Treatment

The delay comes after the FDA made a recent data request requiring Ardelyx to submit additional analyses to better shed light on the novel mechanism of action of the treatment compared to already approved therapies for this patient population.

Tenapanor is an oral medication that acts locally in the gut to inhibit the sodium hydrogen exchanger 3 (NHE3), resulting in a proposed conformational change of the epithelial cell tight junctions, thereby significantly reducing paracellular permeability to phosphate and decreasing phosphate absorption through this primary pathway.

The Delay

Ardelyx has submitted the requested analyses, which is considered a major amendment to the New Drug Application (NDA), which was based on a series of clinical trials involving more than 1000 patients that have met primary and key secondary endpoints.

"While disappointed in the delay, we understand the impact that the COVID-19 pandemic has had on the operations of the agency," said Mike Raab, president, and chief executive officer of Ardelyx, in a statement. "We appreciate the constructive labeling discussions with the agency over the past month and believe that the additional analyses submitted in response to recent dialogue with the agency reinforce the extensive clinical evidence we generated on tenapanor.

“We look forward to continuing to work closely and constructively with FDA during the remainder of the review process. We are confident in the comprehensive data set, are well prepared for the launch of tenapanor upon potential approval and are dedicated to bringing this important medicine to patients.”

The Need

Despite treatment with currently available drugs, 40% of patients continue to have phosphorous levels outside of target ranges in any given month and data shows 77% of patients are unable to consistently maintain target phosphorus levels over a six-month period.

The new PDUFA date will be July 29, 2021.