Ardelyx stock craters as FDA slaps biotech with dreaded 'deficiencies' tag on kidney drug

Mike Raab - Ardelyx
Mike Raab, Ardelyx CEO (Ardelyx)

Shares in Ardelyx are in freefall after the FDA found a series of “deficiencies” with Ardelyx’ application for the kidney disease hopeful tenapanor.

In what CEO Mike Raab said was an “extremely disheartening and disappointing communication from the FDA,” the U.S. regulator, which has already delayed the decision date for the therapy once to the end of the month, is now heaping more pressure on the med.

Specifics were not shared by the FDA, but according to Ardelyx (the FDA doesn’t release the information publicly), the deficiencies that led to the red light were related to a “key issue” which was the size of the treatment effect and its clinical relevance: i.e., whether it actually works.

The FDA is reviewing whether the experimental med tenapanor should be approved for the control of serum phosphorus in adult patients with chronic kidney disease who are on dialysis. The agency has identified deficiencies that “preclude discussion of labeling and post-marketing requirements/commitments at this time,” though the letter “does not reflect a final decision on the information under review,” leaving much in limbo.

Ardelyx has “immediately requested a meeting to discuss the deficiencies” but that request for a meeting “was denied.”

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“This is an extremely disheartening and disappointing communication from the FDA, particularly following the weeks of label discussions that occurred in early April, the fact that our NDA submission included three pivotal trials across 1,000 patients, all which met their primary and key secondary endpoints, as well as the additional data analyses we submitted in late April in response to the FDA's requests," said Raab.

“We plan to work with the FDA to learn more about the identified deficiencies and will seek to resolve them as quickly as possible.”

Shares were down more than 70% Monday evening when the biotech dropped the news after normal trading hours. The shares, which closed the day before at $7.70, were trading down 74% at $1.99 in pre-market trading Tuesday as the fallout continued.