Keryx phosphate binder succeeds in Phase 3 study

Tue Nov 30, 2010 6:00am EST

* Zerenex meets goals of Phase III study

* 6 gram dose reduces serum phosphorus 25 percent

* 8 gram dose demonstrates 28.8 percent reduction

By Bill Berkrot

NEW YORK, Nov 30 (Reuters) - An experimental drug being developed by Keryx Biopharmaceuticals Inc (KERX.O) to lower abnormally high levels of phosphate in the blood of patients with advanced kidney disease succeeded in meeting its goals in a late-stage clinical trial, the company said.

Keryx released the positive top-line data from a 146-patient, short-term Phase III study of its Zerenex phosphate binder on Tuesday, saying the drug produced highly statistically significant results at the two highest doses tested.

End-stage kidney patients on dialysis who received 6 grams of Zerenex per day saw their serum phosphorus levels drop by 25 percent after 28 days to 5.7 milligrams per deciliter from 7.6 mg/dl. Patients who received 8 grams per day of Zerenex experienced a nearly 29 percent drop to 5.3 mg/dl from 7.5 mg/dl.

A dose of 1 gram per day failed to reduce serum phosphorus levels, according to the data.

The drug, an oral ferric iron-based phosphate binder, was given via a one gram formulation so 6 gram patients took six pills a day and 8 gram patients took 8 pills a day, the company said.

"Based on the results of this Phase 3 study, it appears that the Zerenex efficacy and safety profile is emerging in a way that could make it the phosphate binder of choice for dialysis patients," Dr. Julia Lewis, chairwoman of the Zerenex Phase III study program, said in a statement.

"We are very excited to have taken this big step forward towards bringing Zerenex to the patients who are in need of additional alternatives to the existing phosphate binders," added Lewis, professor of medicine, Department of Nephrology, at Vanderbilt University School of Medicine.

The drug appeared to be safe and well tolerated, with nine patients -- 6 percent -- dropping out of the study, the company said.

No clinically meaningful change in serum calcium was seen, but a dose-related reduction in calcium-phosphorus was observed in the study, the company said.

Elevated levels of serum calcium and high levels of calcium-phosphorus product, both of which are believed to be drawbacks associated with some currently marketed phosphate binders, increase the risk of soft tissue calcification and may contribute to serious health problems and death in patients with end-stage kidney disease.

Keryx is currently enrolling patients in a longer-term, 58-week Phase III study of the safety and efficacy of Zerenex that will be used in seeking U.S. approval to sell the drug, the company said. (Editing by Steve Orlofsky)

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