Ardelyx’s Regulatory Update Suggests NDA Approval is in Jeopardy

The company’s stock began dropping on Tuesday with analyst expectation the FDA will issue a Complete Response Letter for tenapanor, its chronic kidney disease therapy.

The FDA has found deficiencies in Ardelyx’s NDA for tenapanor, a first-in-class oral therapy for the control of serum phosphorus in adult patients with chronic kidney disease on dialysis, according to an update from the company. The deficiencies are related to the size of the treatment effect and its clinical relevance.

“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,” Mike Raab, president and chief executive officer of Ardelyx, said in a statement. "We plan to work with the FDA to learn more about the identified deficiencies and will seek to resolve them as quickly as possible."

In April, the FDA extended the PDUFA review period for tenapanor to July 29, 2021. The agency had requested the company to submit additional analyses in light of tenapanor’s novel mechanism of action. Ardelyx has submitted its NDA in June 2020.

At least one analyst is expecting the FDA to issue a Complete Response Letter, and the company’s stock began dropping on Tuesday. “From the sound of things, the agency doesn't plan on approving the drug during this review cycle. The FDA, in fact, refused to even meet with Ardelyx to discuss the NDA's areas of concern,” according to analysts with Motley Fool.

About 80% of patients with chronic kidney disease who are on dialysis require phosphate-lowering therapy. Hyperphosphatemia, an electrolyte disorder in which there is an elevated level of phosphate in the blood, is a major risk factor for cardiovascular morbidity and mortality in patients on dialysis.