Complete Response Letter from FDA for NDA for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis.- Ardelyx.

According to the CRL, while the FDA agrees that "the submitted data provide substantial evidence that tenapanor is effective in reducing serum phosphorus in CKD patients on dialysis," they characterize the magnitude of the treatment effect as "small and of unclear clinical significance." Additionally, the FDA noted that for the application to be approved, Ardelyx needs "to conduct an additional adequate and well-controlled trial demonstrating a clinically relevant treatment effect on serum phosphorus or an effect on the clinical outcome thought to be caused by hyperphosphatemia in CKD patients on dialysis." There were no safety, clinical pharmacology/biopharmaceutics, CMC or non-clinical issues identified in the CRL.

The FDA indicated it is willing to meet with Ardelyx to discuss options for obtaining approval. To that end, the company intends to request a Type A meeting as soon as possible to discuss the CRL and determine potential paths forward for the approval of tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis.