Issues seen with drugs to curb prostate cancer: FDA

WASHINGTON (Reuters) - U.S. regulatory staff have raised concerns about data for two drugs by GlaxoSmithKline Plc and Merck & Co Inc and their effect on reducing the risk of prostate cancer in certain men.

Both drugs are already approved to treat symptoms in men with enlarged prostate, but GlaxoSmithKline Plc is seeking a wider approval to market its drug, Avodart, as a way to curb the chances of prostate cancer in men who are at greater risk of developing the disease.

Food and Drug Administration staff, in documents released ahead of a public advisory meeting on Wednesday, said overall, large trials for each of the drugs showed benefits after four years with Avodart and seven years with Merck’s drug, Proscar -- mostly in men with certain grades of the cancer.

They noted that “neither trial was adequately designed and conducted to characterize the ultimate outcomes of interest,” such as death. “In both trials, there was also an unexpected finding of an increased incidence of high-risk prostate cancers among men receiving” the drugs, they added.”

For Glaxo’s Avodart, advisers also cited concerns about use of biopsies and the impact of the drug on black men, among other issues.

Separately, advisers will also consider whether the new data should be included on the Proscar’s label, although Merck is not seeking formal approval for wider use. Proscar is also known by its chemical name finasteride.

“The benefit of finasteride for the risk reduction in prostate cancer is uncertain since the observed risk reduction of prostate cancer was present only in the subgroup of participants diagnosed” with certain tumors, FDA staff wrote.

At the meeting, an FDA panel of outside experts will weigh both companies’ data before offering the agency its recommendation. The FDA will later make the final decisions.

The FDA released the documents on its website at

Glaxo’s shares were down 1.5 percent at $38.81 and Merck’s shares fell about 1 percent to $34.51, both in early trading on the New York Stock Exchange.

Reporting by Susan Heavey; Editing by Derek Caney and Maureen Bavdek