Ardelyx’s CKD Drug Clears FDA Adcomm Hurdle with 9-4 Vote

FDA_Sarah Silbiger/Getty Images

Courtesy of Sarah Silbiger/Getty Images

Ardelyx has moved one step closer to the possible approval of its experimental chronic kidney disease (CKD) drug following a favorable 9-4 vote from an FDA advisory committee Wednesday afternoon.

The FDA’s Cardiovascular and Renal Drugs Advisory Committee delved into the clinical data for tenapanor, a drug designed to improve the control of serum phosphorus in adult patients with CKD who are on dialysis.

After examining the available information and hearing the testimony of CKD patients who participated in the clinical studies, the majority of the committee agreed the benefits of the medication outweighed its risks as a monotherapy.

The inability to control serum phosphate levels, called hyperphosphatemia, leads to the leaching of calcium from the bones. This causes the bones to become weak and ultimately leads to the formation of calcium deposits in other parts of the body, which can damage organs and blood vessels.

Although FDA researchers raised questions about the magnitude of tenapanor’s treatment effect on lowering those serum phosphate levels, the advisory committee members who supported the data said that even if the effect is largely seen in a subset of patients, it is an improvement over the current standard of care.

Doctors Weigh In 

That was the rationale for Dr. C. Noel Bairey Merz, a cardiologist and a member of the advisory committee. Throughout the presentation, the doctors heard from patients who were unable to see improvements in their phosphorous levels from the current standard of care, she said.  

Bairey Merz said she would prefer to see tenapanor as an add-on treatment, but it should be considered as a monotherapy for those patients who benefited. She suggested the drug as a monotherapy was better than nothing.

Dr. Julia B. Lewis, a nephrologist from Vanderbilt Medical Center and chairperson of the advisory committee, voted in favor of tenapanor’s benefits. She said patients will always appreciate another treatment option.

She also suggested a small subset of dialysis patients will likely respond to tenapanor as monotherapy, and it should be available for them.

Patient Testimonials

Multiple patients addressed the advisory committee meeting, sharing how their lives were improved by tenapanor and the improvements they saw while taking the medication during clinical studies. The patients discussed their improvements in phosphorous numbers as well as the reduction of pill burden from the phosphate binders.

Lisa Evans, a 58-year-old CKD patient on dialysis from Georgia told the committee managing phosphorous levels has always been difficult. She takes an average of four phosphate binders with each meal and is restricted to limited amounts of water at the same time.

“Can you imagine having to take 12 horse pills per day? And I have to take them at different points of the meal, which increases the challenge,” Evans said.

Evans was a tenapanor patient in the Ardelyx study. During the trial, her phosphorous levels were brought under control and she was relieved of her pill burden. However, since leaving the trial, her levels have been creeping up again. She urged the committee to vote in favor of tenapanor in order to give patients another option.

Dawn Edwards has been a kidney patient for 32 years. For 26 years, she said she has been challenged trying to manage her phosphorous levels. She said tenapanor provided her with a reduction of of these levels and the pill burden.

Last year, the FDA issued a Complete Response Letter for the drug candidate despite it hitting its primary endpoint in late-stage studies. The clinical data showed tenapanor reduces serum phosphorus in CKD patients on dialysis but at the time of the CRL, the regulatory agency called the results “small and of unclear clinical significance.”

With the advisory committee hurdle cleared, the FDA will now weigh in. The regulatory agency does not have to vote in the same manner as the committee, but it often does.

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