October 20, 2010 — Prescribing information for gonadotropin-releasing hormone (GnRH) agonists, which are a class of drugs primarily used to treat prostate cancer, will now bear a warning about the potential risk for heart disease and diabetes in men treated with these medications, the US Food and Drug Administration (FDA) announced today.

In May, the FDA announced that a preliminary and ongoing analysis had found that patients receiving GnRH agonists were at a "small increased risk" for diabetes, heart attack, stroke, and sudden death. The revised labels will include cautions in the warnings and precautions section about these potential risks.

GnRH agnoists are marketed under a variety of brand names: Eligard, Lupron, Synarel, Trelstar, Vantas, Viadur, and Zoladex. Generic products are also available.

As a component of androgen-deprivation therapy, GnRH agonists suppress the production of androgens that can stimulate the growth of prostate cancers.

The FDA's notification to manufacturers about the GnRH agonists is based on the agency's review of several published studies, according to the agency.

The relationship between heart disease risk, diabetes, and androgen deprivation therapy has not been without controversy. A medical oncologist specializing in prostate cancer treatment recently defended the safety of the therapeutic approach in an interview with Medscape Medical News.

"There is no convincing evidence that hormone blockade shortens life or causes excess heart attacks if weight gain is attended to and blood sugar levels are kept in check," said Mark Scholz, MD, from the Prostate Cancer Research Institute in Los Angeles, California.

"Hormone blockade extends life in randomized trials, both disease-specific and overall survival. The only studies that show shorter survival are retrospective comparisons in large insurance databases that can't control for the selection biases of physicians who reserve hormone blockade for the 'weak and feeble,' " he explained.

The use of androgen deprivation therapy has been controversial in other ways as well. The approach has been "overused," according to a pair of experts in separate editorials in 2 major medical journals in 2009.

Professional societies have been concerned about adverse events related to androgen deprivation. In February of this year, an advisory jointly issued by the American Heart Association, the American Cancer Society, and the American Urological Association said that "there may be a relationship" between androgen deprivation therapy for prostate cancer and cardiovascular risk.

GnRH Agonists: Label Change - Increased Risk of Diabetes and Cardiovascular Disease (Update)

AUDIENCE: Oncology, Endocrine, Cardiovascular