In April, the U.S. Food and Drug Administration approved Provenge for treatment of prostate cancer that has spread to other parts of the body and is resistant to standard hormone treatment.
For the study, Kantoff's group randomly assigned 512 men to receive Provenge or placebo. All of patients had advanced prostate cancer that had proven resistant to standard hormonal therapy.
On average, men receiving Provenge lived 4.1 months longer than men receiving a placebo, the researchers found. Average survival was 25.8 months for men in the Provenge group, compared with 21.7 months for men in the placebo group, meaning that Provenge extended survival by 22 to 25 percent, Kantoff said.
He contends that if the vaccine were used by men with less severe disease survival, it might be extended for even longer.
"Theoretically, if you take people with less diseases and you stimulate the immune system, you could have a more profound effect, but we don't really know that yet," he said.
Compared with other treatments, such as chemotherapy, radiation and hormone therapy, Provenge has been touted as having fewer and less severe side effects. In this trial, the most common side effects were chills, fever and headache, the researchers noted.
Commenting on the high cost of Provenge, Kantoff said that "this is a treatment given over a four-week period, as opposed to other treatments that are given over many months, where the costs can be high as well, if not comparable to or more expensive [than Provenge]."
For more information on prostate cancer, visit the American Cancer Society.
SOURCES: Philip Kantoff, M.D., professor, medicine, Harva
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