Dive Brief:

  • A Food and Drug Administration advisory panel on Wednesday backed Ardelyx’s drug for kidney disease patients, lending weight to the company’s appeal of a rejection from the agency last year.


  • The FDA tasked the committee with weighing the benefits and risks of Ardelyx’s tenapanor as a way to control potentially dangerous phosphorus levels in dialysis patients with chronic kidney disease. The panel voted 9-4 to back the medicine as a monotherapy and 10-2, with one abstention, in favor of its use in combination with treatments called phosphate binders.


  • Regulators now have 30 days to answer Ardelyx’s latest appeal of their initial decision. The FDA denied the first appeal in February, while suggesting the company could perform additional analyses of its original clinical trials instead of undertaking a new pivotal study to win approval.

Dive Insight:

The regulatory ups and downs of the last two years have led to a “lightning strikes” moment for Ardelyx, Piper Sandler analyst Christopher Raymond wrote in a note to investors. It’s rare for the FDA to convene an advisory panel to review an appeal of a drug rejection and it’s even rarer for that panel to “resoundingly reject” the FDA’s rationale for its decision, Raymond said.

While the FDA doesn’t have to follow the recommendations of its outside advisers, it usually does.

Ardelyx first won approval for tenapanor in 2019 to treat irritable bowel syndrome. Around the same time, the company released a study showing the drug could lower the buildup of phosphorus in kidney disease patients. More positive data followed, and the company filed to expand the use of tenapanor — an application that appeared on track until a three-month FDA delay announced in April 2021.

In July 2021, the agency told Ardelyx it was concerned about the size of the treatment effect and the “clinical relevance” of data suggesting it could lower phosphorus levels. A rejection of the drug application followed, and Ardelyx laid off a third of its workforce as the company’s shares tumbled below $2. The stock had traded above $32 in 2014.

Still, company officials believed in the drug, touting three pivotal trials involving more than 1,000 patients and began an appeal process that finally led to the panel hearing Wednesday.

Committee members said they would welcome more data, especially from studies that would measure the clinical outcomes of reducing phosphorus levels. But ultimately, panel members said they believed that tenapanor was effective and could benefit patients by allowing them to simply take one pill twice a day.

Currently, patients can get overwhelmed by the burden of all the pills they have to take, and many fall off treatment. Indeed, one patient told panel members she had to take “12 horse pills” a day with only small sips of water, a task she found “almost impossible.”

“There is clearly a need for a drug such as this,” said panel member Edward Kasper, director of outpatient cardiology at Johns Hopkins School of Medicine.

Paul Conway, a panel member and representative from the American Association of Kidney Patients, said he believed that the Ardelyx drug offered an important innovation. “There’s an unmet need,” Conway said. “I think the patient experience has disproportionate importance in this decision and that those voices must be listened to.”

Ardelyx currently sells tenapanor for irritable bowel syndrome patients under the brand name Ibsrela. It intends to sell the drug as Xphozah for kidney patients.

Shares climbed about 35% on Wednesday, but still trade at less than $2 apiece.