Prostate Cancer Vaccine Shows Few Side Effects

MONDAY May 31, 2010 -- The newly approved therapeutic prostate cancer vaccine, Provenge, is safe and has few side effects, a new study finds.

In April, the U.S. Food and Drug Administration approved the vaccine for use in men with advanced prostate cancer who had failed hormone therapy.

"Provenge was approved based on both safety and clinical data," said lead researcher Dr. Simon J. Hall, chair of urology at Mount Sinai Medical Center in New York City.

This safety data shows that there are very limited side effects, Hall added.

The advantage of the vaccine for patients with metastatic hormone-resistant prostate cancer is that it has fewer side effects than chemotherapy, which is the only other treatment option for these patients, Hall explained.

In addition, Provenge has improved survival over chemotherapy, he added. The average survival time for men given Provenge is 4.5 months, although some patients saw their lives extended by two to three years.

"This is a newly available treatment, with very limited side effects, compared to anything else that a man would be considering in this state," Hall said.

Hall was to present the results on Monday at the American Urological Association annual meeting in San Francisco.

Data from four phase 3 trials, which included 904 men randomized to either Provenge or placebo, showed the vaccine extended survival, improved quality of life and had only mild side effects.

In fact, more than 83 percent of the men who received Provenge were able to do perform activities without any restrictions, the researchers noted.

In terms of side effects, the most common were flu-like symptoms such as chills, fever and headache, which were seen in 3.5 percent of the men. Usually it took only a day or two for the symptoms to resolve.

More serious side effects, such as infusion reactions, affected 3.5 percent of the patients. Cerebrovascular problems affected 3.5 percent of those who received the vaccine and 2.6 percent of those who received placebo, Hall's group found.

Dr. Nelson Neal Stone, a clinical professor of urology and radiation oncology at Mount Sinai School of Medicine in New York City, said that "the side effects are like having the flu and they can be managed with aspirin."

However, Stone pointed to one big drawback to Provenge: cost. "I've heard $30,000, I've heard $90,000 ... I have no idea what it's going to cost. And who's going to pay for it?" he said.

Provenge is a therapeutic (not preventive) vaccine that is made from the patient's own white blood cells. Once removed from the patient, the cells are treated with the drug and placed back into the patient. These treated cells then cause an immune response, which in turn kills cancer cells, while leaving normal cells unharmed.

According to the FDA, Provenge is given intravenously in a three-dose schedule delivered in two-week intervals.

The vaccine was developed by Seattle-based Dendreon Corp., which conducted initial studies among men with advanced prostate cancer who had already failed standard hormone treatment.

According to American Cancer Society estimates, more than 192,000 new cases of prostate cancer are diagnosed in the United States each year, and 27,360 men die from the disease.

Prostate cancer is the most common form of cancer diagnosed in American men, after skin cancer. More than 2 million American men who have had prostate cancer at some point are still alive today. The death rate is going down and the disease is being found earlier, according to the cancer society.

Posted: May 2010


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