Today's announcement that the U.S. Food and Drug Administration has approved Provengeâ, a new form of therapy for some prostate cancer patients, marks the beginning of an era in which patients' own immune systems become part of the standard therapeutic arsenal against cancer, say Dana-Farber Cancer Institute investigators who led a study of the treatment's effectiveness in patients.
The study - the results of which were presented most recently at the 2010 Genitourinary American Society of Clinical Oncology's annual meeting - is the first large, controlled clinical trial to show that an immune system-based therapy can extend the lives of cancer patients, according to the trial's leader, Philip Kantoff, MD, of Dana-Farber.
"For more than 20 years, scientists have been working on harnessing the immune system in a way that has beneficial effects for cancer patients, notably the prolongation of survival," Kantoff said. "Our study provides proof that such an approach can work."
Unlike preventive vaccines, which bolster the immune system to protect people from contracting an illness, Provenge is an "autologous cellular immunotherapy," or a therapeutic vaccine, that marshals the immune system's disease-fighting forces for people who already have prostate cancer.
The immunotherapy is produced by removing some of a patient's white blood cells - a process called leukapheresis - and then exposing them to a protein from prostate cancer cells and a stimulatory molecule. The process primes the white blood cells to stimulate the immune system and attack prostate cancer when they are re-injected into the body.
The clinical study, a Phase III trial conducted at cancer treatment centers across the country, enrolled 512 patients with advanced prostate cancer that had spread beyond the prostate gland and that grew even when deprived of the hormone androgen, a condition known as metastatic hormone-resistant prostate cancer. Patients were randomly assigned to receive either Provenge, which is manufactured by the Dendreon Corporation of Seattle, or an inactive placebo. Compared to the placebo, Provenge extended a patient's median survival by 4.1 months, improved three-year survival by 38 percent, and reduced the overall risk of death by 22.5 percent.
Approval by the FDA means that Provenge will become available within the next year to prostate cancer patients who meet the criteria of having advanced, metastatic tumors that are hormone resistant. Because of the complexity of making the immunotherapy - which must be individually produced for each patient - there will be a six- to 12-month ramp-up period before it is available to all eligible patients. Patients should check with their doctors to determine if they're candidates for the vaccine, noted Kantoff, who is the director of the Lank Center for Genitourinary Oncology at Dana-Farber/Brigham and Women's Cancer Center, chief of the Division of Solid Tumor Oncology and chief clinical research officer at Dana-Farber, and professor of medicine at Harvard Medical School.
Every year, more than 192,000 men are diagnosed with prostate cancer in the United States, and more than 27,000 die of the disease, according to the American Cancer Society. The number of men with metastatic, hormone-resistant prostate malignancies who might benefit from Provenge is in the tens of thousands.
Provenge is administered to patients three times over the course of a month. It is designed to fit in with other treatments that patients may be receiving.
"As scientists have learned more about the basic workings of the immune system, they've developed increasingly effective ways to exploit the immune response to cancer," Kantoff said. "Provenge is the first fruit of this endeavor to receive FDA approval - the first of what we expect to be many more cancer immunotherapies in the future."
"We are beginning to see the results of years of research into the basic biology of cancer, and of our work to personalize care around the unique characteristics of each patient," said Edward J. Benz, Jr., MD, president of Dana-Farber. "These promising results are a step forward in a long journey."
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