Keryx touts its kidney drug with an FDA decision around the corner

Keryx Biopharmaceuticals' ($KERX) in-development Zerenex helped reduce dangerous buildups of phosphorus in patients on kidney dialysis, meeting its goals in a Phase III study as the company awaits final word from the FDA.

The drug is designed to treat hyperphosphatemia, a common ailment among patients with chronic kidney disease in which phosphorus levels reach dangerous heights. In a late-stage study with 441 patients on dialysis, Zerenex charted a statistically significant reduction in serum phosphorus versus placebo, also meeting secondary endpoints of decreasing the need for need for intravenous iron and erythropoiesis-stimulating agents, or ESAs.

The results were published in the Journal of the American Society of Nephrology.

Now Keryx is awaiting news from the FDA, which has set a Sept. 7 decision deadline on whether to approve Zerenex for hyperphosphatemia. The agency is widely expected to give Keryx's drug the green light, setting the stage for a near-term launch and a chance to compete in the $2.4 billion market for phosphate-binding treatments.

However, Zerenex's commercial potential has long been the subject of debate among analysts and investors. The drug's market entry may well be blunted by soon-to-launch generics of Sanofi's ($SNY) Renvela and Shire's ($SHPG) Fosrenol, two phosphate-lowering therapies indicated for dialysis patients.

Playing a bit of offense, Keryx is taking pains to talk up Zerenex's secondary benefits in serum iron and ferritin, calling its drug a differentiated product in a crowded field. If approved, the treatment would be the only phosphate binder that boosts the body's stores of iron and decreases the need for additional treatments, the company said.

Furthermore, Keryx is working through trials on patients with iron-deficiency anemia, hoping to secure a wider indication for the drug once it hits the market.

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