FDA OKs Vaccine Therapy for Prostate Cancer

April 29, 2010— -- The Food and Drug Administration approved the first therapeutic vaccine for prostate cancer today, after a three years of evaluations with the vaccine's manufacturers and researchers.

Earlier clinical trials of the vaccine, called Provenge, showed that the therapy could extend life by four to five months in men with advanced prostate cancer. But in 2007, the FDA asked for more research since studies curiously showed that Provenge seemed to extend life without slowing the progression of cancer.

"This is real big step," said Dr. David Penson, a researcher on the original Provenge studies and a professor of urologic surgery at Vanderbilt University in Nashville, Tenn. "You're using your body's own immune system to fight the cancer. In the future we hope it will make treatment more effective with few side effects."

An estimated 220,000 men were diagnosed with prostate cancer in 2007 in the United States, according to the National Cancer Institute. About 28,000 men died from the disease that year.

Rather than obliterate new cells in the body as chemotherapy does, Provenge works by boosting the patient's own immune system.

"It's not a miracle, but it's amazing that the immune system can still wake up even when a man has prostate cancer throughout his body," said Dr. Jonathan Simons, president and CEO of the Prostate Cancer Foundation.

"In 1993 if you told someone that you could wake up the immune system to fight prostate cancer, they would have laughed you out of the room," said Simons.

About 18 years ago, Simons said scientists discovered that cells in our immune system called dendritic cells act as detectives that hunt down and identify potential invaders like cancer. The dendritic cells then "awake" or activate other cells in the immune system such at T-cells or B-cells to seek and destroy the cancer invaders.

Simons said it wasn't until 2000 that researchers believed the immune system of a person with severe prostate cancer could "wake up" and start to recognize the cancer as a disease.

Provenge works unlike other vaccines in which a standard dose is manufactured and distributed to doctors.

Men who are candidates for the vaccine must give a blood samples. The white blood cells are isolated, shipped to a specialized lab, and treated in a way that "trains" the white blood cells to recognize and attack cancer.