On October 17, tenapanor became the first and only phosphate absorption inhibitor approved by the FDA to lower serum phosphorus levels in adults with chronic kidney disease (CKD).
Individuals receiving dialysis as an add-on therapy for patients who either do not respond to phosphate binders or are intolerant to any dose of phosphate binder therapy may benefit from the approval.
According to a press release from Ardelyx, this single pill, which is taken twice daily, has a first-in-class mode of action that prevents phosphate from being absorbed through its main channel.
Tenapanor is a first-in-class phosphate absorption inhibitor that works in the gut and has a unique mode of action. It interferes with the sodium hydrogen exchanger 3 (NHE3), lowering phosphate absorption along the paracellular pathway's main channel of phosphate absorption.
Every 30 minutes, your kidneys, each about five inches, filter all the blood in your body. They exert much effort to eliminate waste, poisons, and extra fluid. Additionally, they support blood pressure management, promote the generation of red blood cells, maintain bone health, and regulate vital blood molecules. Healthy kidneys are essential for sustaining overall health, yet more than one in seven Americans is estimated to suffer from CKD.
Unfortunately, CKD impairs the ability of the kidneys to filter blood properly and fulfill needed duties. Thus, extra fluid and blood waste build up in the body, which may result in various health issues, including heart disease and stroke.
"Hyperphosphatemia management has been a persistent clinical challenge, as the majority of patients receiving maintenance dialysis are unable to consistently achieve target serum phosphate concentrations despite treatment with phosphate binders."- Glenn Chertow of Stanford University
Tenapanor, Chertow says, is an inhibitor of phosphate absorption rather than a phosphate binder. The recently approved medication has been found to assist in raising the proportion of patients attaining target blood phosphate concentrations in patients who are not responding well to phosphate binder treatment.
Impact of tenapanor on those with CKD
Three phase 3 clinical studies, including PHREEDOM, BLOCK, and AMPLIFY, assessed the effectiveness and safety of tenapanor as a monotherapy and, in conjunction with phosphate bunder therapy, led to the FDA's approval.
The three studies showed that tenapanor effectively decreased high serum phosphorus in maintenance hemodialysis patients and achieved their primary and essential secondary objectives. Additionally, the OPTIMIZE and NORMALIZE open-label clinical studies examined various strategies for incorporating tenapanor into clinical practice. Diarrhea, which occurred during the first few days of treatment in 43% to 53% of patients and at least 5% of tenapanor-treated patients with CKD receiving dialysis throughout the trials, was the most frequent side event that patients reported. Most reported incidences were mild to moderate in intensity and subsided with time or after a dosage decrease.
In the studies, only 5% of individuals receiving tenapanor reported experiencing severe diarrhea, which was less prevalent. They warn that children under six and those with a known or possible mechanical gastrointestinal blockage to stay away from tenapanor.
Ardelyx's CEO and president, Mike Raab, says the approval of tenapanor provides a new mechanism and new choice for patients who, despite therapy with phosphate binders, continue to have excessive phosphorus, and is a significant milestone for dialysis patients, families, and the nephrology care community.
Raab concludes: "This approval is also a tribute to the patients, families, physicians, and clinical trial personnel who participated in the development of [tenapanor]. There is a high level of anticipation and enthusiasm for the launch of [tenapanor] from the kidney community, and [Ardelyx's] world-class team will enter the marketplace well positioned with a first-in-class product."