AMPLIFY Phase III study of RDZ 5792 meets primary endpoint in hyperphosphatemia.- Ardelyx

Ardelyx reported positive results from AMPLIFY, a pivotal Phase III study of RDZ 5792 (tenapanor) in combination with phosphate binders in patients with chronic kidney disease (CKD) on dialysis whose hyperphosphatemia was not previously controlled with binders alone. The AMPLIFY study met the primary endpoint and all key secondary endpoints, including demonstrating a statistically significant reduction in serum phosphorus levels for patients treated with tenapanor and phosphate binders compared to phosphate binders alone. Tenapanor is an investigational, first-in-class, small molecule, non-binder, phosphate absorption inhibitor being developed to treat hyperphosphatemia in patients with CKD on dialysis.

For the primary endpoint, patients treated in the tenapanor arm (tenapanor in combination with phosphate binders, n=116) had a statistically significant mean reduction in serum phosphorus from baseline to the end of the four-week treatment period of 0.84 mg/dL, as compared to those treated in the binder arm (placebo in combination with phosphate binders, n=119) who had a mean reduction of 0.19 mg/dL. Patients in the tenapanor arm had statistically significant decreases in serum phosphorus during all four weeks ranging from 0.84 to 1.21 mg/dL. During the treatment period, up to 49.1% of patients in the tenapanor arm achieved a serum phosphorus of <5.5 mg dl which was statistically significant compared with up to 23.5 in the binder arm. there was a statistically significant 22 to 24 reduction in fgf23 levels in the tenapanor arm as compared to the binder arm. elevated levels of fgf23 are associated with an increased risk of major cardiovascular events.>

Tenapanor was well tolerated. Only 4.3% of patients in the tenapanor arm discontinued treatment compared to 2.5% in the binder arm. The single adverse event with a placebo-adjusted rate greater than 3% was loose stools/diarrhea at 36%, where most incidents were reported within the first five days of treatment, were transient in nature and the median time to resolution was four days after onset. Notably, only 2.6% of patients in the tenapanor arm discontinued treatment due to loose stools/diarrhea, as compared to 0.8% in the binder arm. There were no serious adverse events related to tenapanor.