U.S. reviews diabetes, heart risk with prostate drugs

WASHINGTON (Reuters) - The U.S. Food and Drug Administration is examining if certain hormone treatments for men with prostate cancer pose a greater risk of diabetes or heart problems than other therapies.

The FDA is looking at data from published studies to determine the risks with commonly used Gonadotropin-Releasing Hormone (GnRH) agonist drugs, the agency said on Monday.

The products include Abbott Laboratories' Lupron, AstraZeneca Plc's Zoladex, Watson Pharmaceuticals Inc's Trelstar, Endo Pharmaceuticals Holdings Inc's Vantas, Sanofi-Aventis SA's Eligard and Pfizer Inc's Synarel.

The agency said it has not made any conclusions about GnRH agonists, which suppress the production of testosterone, a hormone that helps fuel growth of prostate cancer.

Suppressing testosterone has been shown to shrink or slow the growth of prostate cancer. The treatment is known as androgen deprivation therapy.

However, the FDA noted that patients should be monitored for potential onset of diabetes or cardiovascular disease that can cause heart attacks, stroke and sudden cardiac death.

The FDA said six studies showed a small increased risk of diabetes or heart disease in patients treated with the drugs when compared with other prostate cancer therapies.

"However, these studies have design limitations that make it difficult to confirm a cause-and-effect relationship," an agency statement said.

The studies included limited information about drug exposure, varying definitions for heart disease, missing data on heart disease risk factors and other problems, the FDA said.

Patients should not stop taking the drugs unless a doctor tells them to, the FDA advised.

Some GnRH agonists also are prescribed at times to women and children to treat other conditions. The FDA said there were no known comparable studies that evaluated the risk of diabetes and heart disease in those groups.

Sanofi is evaluating cases of elevated insulin and blood clots "to determine whether labeling changes or other actions are required," company spokeswoman Emmy Tsui said.

The company "remains confident in the overall safety profile of Eligard based on clinical trials and post-marketing surveillance," company spokeswoman Emmy Tsui said.

Abbott spokeswoman Elizabeth Hoff said the prescribing instructions for Lupron list diabetes, increased glucose and cardiovascular events as potential problems.

Officials at Pfizer and AstraZeneca had no immediate comment. Other companies did not immediately respond.

In February, various doctors' groups wrote in the journal Circulation that they felt androgen deprivation treatment was likely to raise the risk of heart attack. They called for studies to determine the level of risk.

The FDA posted its notice on its website at link.reuters.com/kyv42k.

(Reporting by Lisa Richwine and Susan Heavey; Editing by Bernard Orr and Richard Chang)