After long fight, Ardelyx finally bags FDA approval for chronic kidney disease med Xphozah

The third time’s the charm for Ardelyx and its chronic kidney disease med Xphozah (tenapanor). After being hit with two stinging rejections in the last two years, the FDA has finally given the drug its stamp of approval.

Xphozah, a phosphate absorption inhibitor, is now approved to control serum phosphate in adult chronic kidney disease patients who are on dialysis but can’t tolerate or have an inadequate response to treatment with a phosphate binder.

The condition, also called hyperphosphatemia, is estimated to affect most of the 550,000 U.S. patients with chronic kidney disease who are on maintenance dialysis, according to the company.

Ardelyx has been climbing a rocky path to this approval since receiving an FDA complete response letter in 2021, when the agency flagged concerns with the med’s treatment effect and deemed it “small and of unclear clinical significance."

The rejection came as a surprise to both Ardelyx and analysts. At the time, Piper Sandler analysts said they were “flummoxed” by the agency’s “conflicting messaging” around the application.

Instead of conducting another trial as requested, the company laid off 65% of its workforce and filed a Formal Dispute Resolution Request with the FDA’s Office of Cardiology, Hematology, Endocrinology and Nephrology. That appeal was denied, leaving Ardelyx to go up the chain of command to the FDA's Office of New Drugs.

The Hail Mary was successful and resulted in an advisory committee meeting to review the drug's data. After an eight-hour deliberation, the FDA’s Cardiovascular and Renal Drug Advisory Committee voted 9-4 in favor of the med.

The ultimate victory will prove crucial for the company and its financial future.

When Ardelyx saw its first rejection, the biotech was sitting on $172 million in cash and equivalents. That number dwindled along the regulatory path and stood at just $33.7 million in the first half of 2023. 

The company aims to make Xphozah available in November.

Ardelyx's other commercial product is irritable bowel syndrome med Ibsrela, which also uses the active ingredient tenapanor.