The FDA is seeking input from committee members about the phosphate lowering effect seen in trials for tenapanor, which now has the brand name of Xphozah.
The FDA plans to hold a meeting of the Cardiovascular and Renal Drug Advisory Committee for Ardelyx’s Xphozah (tenapanor) for the control of serum phosphorus in adult patients with chronic kidney disease (CKD) who are on dialysis.
This is an interim response to the company’s second appeal of the agency’s complete response letter, which was issued in July 2021. Regulators at that time noted that data submitted indicate the treatment effect is small and of unclear clinical significance. They had requested an additional study to demonstrate that Xphozah lowers serum phosphorus.
Ardelyx filed the first appeal in November 2021, which was denied. The second appeal was filed in February 2022.
“We are pleased that the Office of New Drugs has acknowledged the importance of including input from expert clinicians, as part of an advisory committee meeting in order to further evaluate the clinical meaningfulness and significance of the phosphate reduction we have demonstrated with Xphozah,” Mike Raab, president and chief executive officer of Ardelyx, said in a press release about the advisory committee meeting. “While we await direction from the OND on the timing of this meeting, we look forward to the opportunity to further discuss Xphozah with the Cardiovascular and Renal Drugs Advisory Committee."
Since that time, additional data on Xphozah has been released, most recently at the National Kidney Foundation 2022 Spring Clinical Meetings early in April. Ardelyx has completed three phase 3 pivotal trials, and two phase 4 clinical trials (OPTIMIZE and NORMALIZE) for Xphozah, a first-in-class, phosphate absorption inhibitor.
In the OPTIMIZE phase 4 trial, Xphoza as monotherapy helped 63% of patients with uncontrolled hyperphosphatemia who were naïve to phosphate binder therapy to achieve target serum phosphate levels. For those with uncontrolled hyperphosphatemia despite being on treatment with phosphate binders, switching to Xphozah or adding Xphozah to a reduced binder dose enabled 34% to 38% of these patients to achieve target levels.
In the NORMALIZE phase 4 trial, up to 49.4% of patients treated with Xphozah monotherapy or in combination with sevelamer achieved a serum phosphate level within the normal range during the 18-month treatment period, which is 66.3% better than standard of care.
Hyperphosphatemia is a serious condition resulting in an abnormally elevated level of phosphorus in the blood. It is estimated to affect the majority of the 550,000 patients in the United States with CKD on dialysis. The kidney is responsible for regulating phosphorus levels, but when kidney function is significantly impaired, phosphorus is not adequately eliminated from the body.