Advisory Panel Concerned About Possible Risk of Aggressive Prostate Cancer
By Matt McMillen
WebMD Health News
Reviewed by Laura J. Martin, MD
Dec. 1, 2010 -- An FDA advisory committee has voted against approval of two drugs for the prevention of prostate cancer because of a link to increased risk of high-grade, aggressive forms of the disease.
GlaxoSmithKline's Avodart and Merck's Proscar are approved to treat benign prostatic hyperplasia (BPH), or enlarged prostate, which is common among men over the age of 50. In studies, both drugs showed a nearly 25% reduction in the risk of developing low-grade forms of prostate cancer compared to participants taking a placebo.
FDA medical officer Yang-Min Ning, MD, PhD, says such forms of cancer "propose very little threat to men during their lifetime."
However, those same studies found that a small number of men actually developed deadlier forms of the disease. Neither company was able to state unequivocally that the drugs themselves were not the cause.
"High-grade forms of the disease have very poor outcomes," says Wyndham Wilson, MD, PhD, of the National Cancer Institute and chair of the Oncology Drugs Advisory Committee. "[In each study] there is more high-grade disease than in placebo, and that's what we're all worried about."
Prostate cancer is the second most common cancer in men (skin cancer is first) and the second highest cause of cancer death in men, according to the CDC. More than 200,000 cases were diagnosed in 2006; nearly 30,000 men died from it in that same year.
Concerns About Study Data
In reviewing the companies' supporting data, the FDA criticized the studies that both Merck and GlaxoSmithKline conducted for the small number of African-American men included.
"African-Americans are a high-risk population, but they are underrepresented here," says Mark Theoret, MD, an FDA medical officer who reviewed the study submitted by Merck.
Of particular concern to the committee was the fact that the drugs, if approved as preventive medications, would be given to otherwise healthy men. Several of the committee members argued that doing so would place such men at risk, and that the benefits of the drugs did not offset such risk.
"A much greater weight should be placed on risk when you're dealing with a preventative agent," Wyndham says.
"I wanted to vote 'yes' so bad," says committee member James Kiefert, a patient representative from Olympia, Washington. But for him and other committee members, there were too many unanswered safety questions. "I need more data to say to my sons, I'd like you to start taking this drug."
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