Washington Editor

The FDA has granted marketing approval to Genzyme Corp.'s Renvela (sevelamer carbonate) for the control of serum phosphorus in patients with chronic kidney disease (CKD) on dialysis, the firm said.

The drug binds phosphate in the gastrointestinal tract to decrease absorption and thereby reduce the body's burden of phosphate. High levels of serum phosphorus, known as hyperphosphatemia, have been linked to cardiovascular disease and have been implicated as a central component of a metabolic and bone abnormality syndrome known as chronic kidney disease-mineral and bone disorder (CKD-MBD).

Renvela, which has been shown to be a successful therapy in controlling serum phosphorus levels, is a next-generation buffered form of Genzyme's Renagel (sevelamer hydrochloride), a phosphate binder approved by the FDA in 1998 for use in patients with CKD on dialysis.

Renagel, which is available in about 60 nations worldwide, is used by more than 350,000 patients, said John P. Butler, president of Genzyme Renal.

While Genzyme currently plans to continue to make Renagel available to patients "for the foreseeable future," Butler told BioWorld Today the firm's long-term goal is to have patients transition to Renvela.

"If patients are well controlled on Renagel without any issues, we certainly don't want to force physicians to change their therapy," he explained.

However, Butler said, the company plans to focus its promotional efforts on Renvela.

He maintained that Genzyme's marketing focus on Renvela is not tied to the 2014 expiration of Renagel's patent. That patent, Butler said, also covers Renvela.

Study results showed that patients on Renvela, which includes a carbonate buffer, were more likely to maintain bicarbonate levels and had a lower incidence of gastrointestinal adverse events than patients receiving other phosphate binders.

Genzyme also is planning to seek approval in the first half of next year of Renvela in predialysis patients with CKD, Butler added.

Last week an FDA advisory panel voted 8 to 4, with one abstention, that the FDA should approve the use of phosphate binders in predialysis patients with hyperphosphatemia. The panelists called for more testing of the drugs in that population, but could not agree on whether completed trials were needed before regulators allowed a labeling change indicating the drugs' use in predialysis patients. (See BioWorld Today, Aug. 17, 2007.)

At the Oct. 16 FDA advisory meeting, Genzyme provided the agency and its expert advisers with some data from a completed study of Renvela in predialysis patients.

The full results of that study will be released in a poster presentation on Nov. 1 at the American Society of Nephrology's Renal Week conference in San Francisco, Butler said.

Renvela will be available in the first quarter of 2008 as an oral drug in 800-mg tablets, Butler said.

However, he noted, Genzyme plans to pursue approval of the product in a powder form, which can be added to water to make a liquid mixture for patients who have difficulty swallowing.

The firm also plans to seek approval of Renvela for use in pediatric patients, Butler said.

The company is negotiating the study protocol for Renvela in children, he said, adding that Genzyme is aware that Renagel, which has been studied in children but has not yet been approved for that population, currently is being used by physicians in pediatric patients.

"Knowing that the powder formulation was going to be available, it just makes sense to use that formulation in a pediatric population vs. an 800-mg tablet," Butler said.

The convenience of having Renvela available in multiple dosage forms, said Craig B. Langman, head of kidney disease at Children's Memorial Hospital in Chicago, will make the drug "exceptionally appealing for multiple patients groups."

He noted that Renvela was not only approved for patients on hemodyalysis, but also for patients on peritoneal dialysis.

"It's the first time that [the FDA] recognized that controlling phosphorus is just as important for that mode of dialysis," Langman said in an interview. "They've ignored it up until now, and I think they've corrected an oversight."

Butler noted that the FDA also this week approved Renagel for use in patients on peritoneal dialysis.

The approval of Renvela, noted Langman, the Isaac A. Abt MD Professor of Kidney Diseases at the Feinberg School of Medicine at Northwestern University, is a "continuing step forward in the care of CKD-MBD, that everybody is so concerned about."

Genzyme also is pursuing regulatory approvals of Renvela in Europe, South America and in other markets internationally.

Shares of Genzyme (NASDAQ:GENZ) rose 11 cents Monday, to close at $71.71.