GlaxoSmithKline Plc failed to win a U.S. panel’s backing for expanded use of its enlarged-prostate therapy Avodart to treat the estimated 1 million American men at risk for prostate cancer.
Avodart’s benefits don’t outweigh the risks that some patients will develop aggressive tumors, as seen in a study, outside advisers to the Food and Drug Administration said in a 14-2 vote today at the agency’s headquarters in Silver Spring, Maryland. The panel separately voted that Merck & Co.’s enlarged-prostate treatment Proscar also failed to show a favorable risk-benefit ratio in preventing prostate cancer in healthy men. Merck, based in Whitehouse Station, New Jersey, isn’t seeking a formal approval to prevent prostate cancer.
Avodart reduced cancer diagnoses by 23 percent after four years, a finding that London-based Glaxo says may help men avoid unnecessary surgery, radiation treatment and hormone-deprivation therapy. The FDA’s advisers raised concerns that the drug may be masking harmful tumors by lowering levels of prostate-specific antigen, a protein used to detect cancer in the blood.
“We simply may be delaying diagnosis of the high-grade disease and that is the last thing you want to do when you’re trying to cure patients with prostate cancer,” said Wyndham Wilson, the panel chairman, who is chief of lymphoma therapeutics at the National Cancer Institute’s Center for Cancer Research, in Rockville, Maryland.
FDA approval was expected to add more than $1 billion to annual sales before safety risks emerged, according to Navid Malik, an analyst at Matrix Corporate Capital, in London. The FDA usually follows its panels’ recommendations and is scheduled to decide on the new use by January.
About 750,000 men in the U.S. took Avodart in the 12 months ended Oct. 31, according to Glaxo. The drug was introduced in the U.S. in 2003 and had global sales of 530 million pounds ($830 million) last year, accounting for less than 2 percent of revenue. U.S. sales were 148 million pounds. Worldwide Avodart sales will reach 831 million pounds in 2013, according to the average forecast of four analysts surveyed by Bloomberg.
The American Cancer Society estimates that 217,730 men will be diagnosed with prostate cancer this year and 32,050 will die of the disease. Avodart would be the first medicine approved to prevent prostate cancer in men at risk for the disease, identified as those who have elevated PSA levels and have had a previous negative biopsy because of clinical concern.
Glaxo’s study tested once-daily Avodart capsules against a placebo. Biopsies were scheduled after two and four years. Aggressive tumors were found in 29 men on the drug, or 0.9 percent, compared with 19 men on placebo, or 0.6 percent, according to data first reported in April 2009.
One aggressive tumor may be expected for every 200 patients treated with Avodart, according to the FDA’s analysis of the data. Sixty men would need to be treated to prevent clinically relevant cancer in one man, the agency said.
Avodart and Proscar seem to have an effect mainly on low- grade tumors that are unlikely to cause death, the FDA said.
“We’re talking about people who don’t have cancer and our bar has to be different in what risk we will accept,” said panel member Mikkael Sekeres, associate professor of medicine at the Cleveland Clinic Taussig Cancer Institute in Ohio.
Merck told the FDA that adding data from a study it reported in 2003 would help doctors make informed treatment decisions. In that study, Proscar reduced prostate cancer diagnoses by 26 percent after 7 years in healthy men at least 55 years old. The drug also was linked to a higher percentage of aggressive tumors in some patients.
“This is a comprehensive picture of two trials that are very similar,” Richard Pazdur, head of the FDA’s office of Oncology Drug Products, told the panel.
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