Keryx's Zerenex reduces phosphorus, raises iron stores in dialysis patients

Keryx Biopharmaceuticals' Zerenex (ferric citrate) may reduce dialysis patients' need to take multiple drugs to reduce serum phosphorus, raise iron stores and reduce intravenous iron and erythropoietin-stimulating agents usage, according to Phase 3 clinical trial results published in the Journal of the American Society of Nephrology.

The study was a multicenter, randomized, open-label trial in 441 ESRD patients on hemodialysis or peritoneal dialysis designed to determine the safety and efficacy of Zerenex. Patients were randomized to receive either ferric citrate or another phosphorus-binding agent for 52 weeks. This was then followed by a 4-week period in which patients taking ferric citrate were again randomized to either continue on the medication or switch to placebo. The drug met the study's primary endpoint, demonstrating a statistically significant change in serum phosphorus versus placebo over the four-week placebo control period.

Zerenex also demonstrated statistically significant increases in serum ferritin and transferrin saturation (TSAT), and significant reductions in the use of IV iron and ESAs, versus an active control of Renvela (sevelamer carbonate) and/or Phoslo (calcium acetate) over the 52-week active control period of the study. In addition, mean hemoglobin levels were higher in subjects treated with Zerenex as compared to subjects treated with active control.

“Ferric citrate binds the phosphorus in food and also increases iron in the blood, and it allows patients to need less or no IV iron and medicines to make their bone marrow produce more blood cells,” said Julia Lewis, MD, lead investigator, nephrologist and professor of medicine at Vanderbilt University Medical Center. She also noted that patients on dialysis often experience many serious adverse medical events, many of which require hospitalization, and that ferric citrate was linked with fewer of these events compared with currently available phosphorus-binding medications. “While benefiting patients, ferric citrate is estimated to also actually reduce the cost of caring for dialysis patients by reducing IV iron and ESA usage, as well as hospitalizations.”

Keryx Biopharmaceuticals' New Drug Application for Zerenex is currently under review by the U.S. Food and Drug Administration.

The article, entitled “Ferric Citrate Controls Phosphorus and Delivers Iron in Patients on Dialysis,” appears online at http://jasn.asnjournals.org/