FDA denies Ardelyx’s appeal against kidney drug rejection, hammering another nail in tenapanor’s coffin

FDA denies Ardelyx’s appeal against kidney drug rejection, hammering another nail in tenapanor’s coffin

The FDA has deflated Ardelyx’s attempt to recover quickly from a complete response letter. With Ardelyx looking to sidestep a request for another trial, the FDA held its ground and denied the appeal—leaving the biotech looking to a Hail Mary pass to overturn the decision.

Ardelyx’s woes date back to last summer, when the FDA raised concerns with the evidence submitted to support approval of chronic kidney disease (CKD) drug tenapanor. The FDA agreed Ardelyx had found the drug, which inhibits the sodium-proton exchanger NHE3, reduces serum phosphorus in CKD patients on dialysis, but deemed the treatment effect to be “small and of unclear clinical significance.”

Facing a request for an additional “adequate and well-controlled trial,” Ardelyx laid off 65% of its staff and filed a Formal Dispute Resolution Request with the Office of Cardiology, Hematology, Endocrinology and Nephrology (OCHEN). The FDA office responded with an appeal denied letter (ADL).

Ardelyx plans to respond to the denial by escalating the matter. Having failed to persuade OCHEN of the merits of its case, Ardelyx is preparing to appeal the ADL to the Office of New Drugs (OND). The FDA’s appeal process allows companies to go up the chain of command step by step, culminating in a request for the commissioner to review the matter.

The next milestone for Ardelyx is penciled in for April, when it expects to learn OND’s decision about its latest appeal. If successful, Ardelyx could refile for approval without running an additional study. Ardelyx is proposing to include new analyses of existing phase 3 results, as well as an assessment of the benefits and risks of tenapanor and a proposal for how to label the drug.

Another rejection will leave Ardelyx in a sticky situation. Ardelyx ended September with $142 million in the bank, a sum it sought to eke out by laying off 65% of its staff. The biotech burned through $47 million over the first nine months of last year.

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