New drug may treat gout, U.S. researchers find

WASHINGTON (Reuters) - A new drug that imitates a blood-clearing enzyme missing in humans appears to safely treat serious cases of gout, U.S. researchers reported on Sunday.

The Savient Pharmaceuticals drug, called pegloticase, helped remove uric acid, which causes the painful, needle-like crystals that clump around fingers, toes and other joints in the condition.

A phase III trial of the drug -- the last stage of human testing before a company can seek U.S. Food and Drug Administration approval -- showed that uric acid levels fell to target levels among all patients who got it within six hours after being intravenously infused with the drug.

One infusion kept levels down for at least six months in 40 percent of the patients, the researchers told a meeting in San Francisco of the American College of Rheumatology.

"There hasn't been a new drug for gout in the U.S. for over 40 years," Dr. John Sundy, a rheumatologist at Duke University Medical Center in North Carolina, who led the study, said in a statement.

"While most gout patients do well with the drug allopurinol, there is a subset of about 50,000 patients in the U.S. who don't respond to it or who can't tolerate it and who have no real alternatives. These are the patients who might benefit from a new therapeutic option."

Gout was depicted in literature as a disease of men who eat and drink too much, and while it can be linked with lifestyle, the disease has genetic causes too.

An estimated 2 million to 3 million people in the United States have the condition.

"The typical patient is male, probably in his 40s or 50s, who suddenly develops searing pain in one of his big toes," Sundy said.

Most mammals have a gene that makes an enzyme called uricase that breaks down uric acid, but humans lack the ability. So if uric acid builds up, the body cannot easily get rid of it.

The infusions were not without side effects, which included back or chest pain, chills, nausea and headaches.

Savient Pharmaceuticals is hoping to license the drug, made under the brand name Puricase.

Analysts have said large drug companies such as Pfizer Inc, Amgen Inc, Roche Holding AG and Johnson & Johnson may be interested in buying Savient or partnering in producing Puricase.

(Reporting by Maggie Fox; Editing by Cynthia Osterman)