Ardelyx wins long battle for FDA approval of kidney-disease treatment

By Eleanor Laise

Drug previously rejected by regulators gets green light and is set to launch later this year

Ardelyx Inc. (ARDX) on Tuesday won its long fight for U.S. regulatory approval of a treatment designed to help patients with chronic kidney disease.

The biopharma company said late Tuesday that the U.S. Food and Drug Administration on Tuesday approved tenapanor, marketed under the brand name Xphozah, for control of serum phosphorus in patients with chronic kidney disease on dialysis. A high level of phosphorus in the blood is often a sign of kidney damage and can lead to weak bones, joint pain, cardiovascular problems and other issues.

The approval concludes an extraordinary comeback for Xphozah. Ardelyx's application for approval of the treatment was previously rejected by the FDA in July 2021, when the agency said the drug's effect was "small and of unclear clinical significance." To preserve cash, Ardelyx a few months later said it would cut its workforce by 65%, but it also pursued multiple appeals of the agency's decision. An FDA advisory committee voted last November that the benefits of Xphozah outweigh its risks. The agency late last year ultimately granted Ardelyx's appeal, and the company resubmitted its Xphozah application to the FDA in April.

More than 550,000 people in the U.S. have chronic kidney disease and are on maintenance dialysis. The vast majority of them have high phosphorus levels, also called hyperphosphatemia, according to Ardelyx.

High phosphorus levels "must be taken care of in these patients, and the current therapies are mostly insufficient in doing so," Ardelyx CEO Mike Raab told MarketWatch.

Chronic kidney disease patients with high phosphorus levels have traditionally been treated with phosphate binders that can soak up phosphorus from food during digestion, but that approach can require patients to swallow a large number of pills. The Xphozah treatment requires two pills a day, "each the size of a Tic Tac," Raab said.

The FDA approved Xphozah as add-on therapy in patients who can't tolerate or have an inadequate response to phosphate binders, Ardelyx said in a release.

Xphozah, which will be Ardelyx's second U.S. product launch, should be available sometime in November, Raab said.

Ardelyx will present updated data on Xphozah for hyperphosphatemia at an American Society of Nephrology meeting in early November, the company said in a release Monday.

Ardelyx shares jumped in late September after Japanese regulators approved tenapanor for hyperphosphatemia in adults with chronic kidney disease on dialysis.

Ardelyx shares fell 0.6% on Tuesday and have gained 21% in the year to date, while the S&P 500 SPX has gained 13.9%.

-Eleanor Laise

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10-17-23 1924ET

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