Fate of Ardelyx kidney disease drug remains unclear

Nov. 16, 2022

An outside advisory committee to the FDA is set to discuss Ardelyx's drug for use by chronic kidney disease patients, but the agency is still seemingly skeptical.

In a briefing doc shared ahead of today's Cardiovascular and Renal Drug Advisory Committee meeting, staff reviewers raised concerns over unclear benefits of Ardelyx's NHE3 inhibitor tenapanor.

According to the briefing doc, all currently marketed products for the control of serum phosphorus (s-P) levels in patients with CKD on dialysis were approved based on their ability to lower serum phosphorus levels in the blood. "If the magnitude of the effect is significantly smaller than that of currently approved products, then applicants will need to address the clinical relevance," stated the FDA.

Tenapanor, branded as Ibsrela, was approved by the FDA in April for irritable bowel syndrome. It's road to approval for CKD, however, has been rocky.

Back in July 2021, Ardelyx was handed a Complete Response letter pertaining to its NDA for tenapanor for the control of s-P in adults with CKD on dialysis. The agency characterized the magnitude of the treatment effect as "small and of unclear clinical significance" and asked the drugmaker to conduct an additional clinical trial. 

Ardelyx formally disputed the decision in Dec. 2021 – a mechanism by which applicants can obtain formal review of any FDA decision by raising the matter with the supervisor of the employee who made the decision. Ultimately, this lead to today's AdComm reassessment.

Currently approved treatments all come with gastrointestinal side effects and the pill burden can be high. If ultimately approved, Ardelyx's treatment, which will be branded as Xphozah, will cut the pill burden down to two (but still comes with a touch of diarrhea).