March 30, 2007 -- A Food and Drug Administration (FDA) advisory panel announced Thursday that a new treatment designed to turn the body's own immune system against deadly prostate cancer tumors is both safe and effective.
The 17-member panel voted unanimously that the drug is safe, and 13-4 that substantial evidence exists suggesting that it is effective in treating prostate cancer.
The decision, though not officially binding, could pave the way for the treatment's consideration by the FDA as a standard therapy for certain cases of prostate cancer.
The treatment, called Provenge, was developed by Seattle's Dendreon Corp. It is the first in what many hope could be a new line of cancer treatments known as "active cellular immunotherapy."
In essence, the treatment trains the body's own immune cells to recognize and attack existing prostate cancer cells.
And though Thursday's advisory panel meeting in Washington, D.C. was just the first step toward FDA approval, some experts in the field are already hopeful that the therapy could open up a new chapter in the fight against prostate cancer.
"The technology is innovative and exciting," says Dr. E. Roy Berger, a prostate cancer specialist at John T. Mather Memorial Hospital in Port Jefferson who is involved in the clinical research for the treatment.
"We now have two arrows in the quiver other than hormones when treating prostate cancer."
Dr. Johannes Vieweg, chair of urology at the University of Florida in Gainesville and an expert in immunotherapy, is not directly involved with the research on Provenge. But he says he is "delighted" that the advisory panel rendered a favorable decision.
"This is the first-ever cancer vaccine that targets established tumors," Vieweg says. "If this drug is approved, it will just open up more investigation in this area."
However, he says that the treatment still faces obstacles before it becomes a regular offering in prostate cancer treatment.
"This is not ready for too much excitement yet," he says. "The drug has been shown to prolong survival in these patients by four and a half months. This is a very good result, but the issue is that more studies have to occur now to determine the true benefits."
Custom-Made Cancer Treatment
Every year, 230,000 men are diagnosed with prostate cancer every year. Edwardo Garcia of San Diego, a Provenge trial patient, was one of these men seven years ago. At the time, his doctor did not have much good news.
"He told me it looked pretty bad," Garcia says.
Garcia was enrolled in a trial of Provenge four years ago. Today, at age 83, he still lives with his cancer. However, he believes the treatment played a big part in his survival and health thus far.
"The cancer is still there, but they found out it doesn't grow anymore," Garcia says. "So I do have cancer, and this is not going to cure me, but I have had seven years of life that I would not have had if I did not have the drug.
"This is not a miracle drug, but it helped me live seven years more."
Even though the treatment is not designed to prevent cancer, some cancer experts call it a "vaccine" because it enlists the help of the immune system in battling cancer in somewhat the same way a vaccine would in fighting a viral infection.
"It is a vaccine in the sense that it juices up the immune system," said ABC News Medical Editor Dr. Timothy Johnson on "Good Morning America" Thursday. "It doesn't prevent cancer, but it treats it."
The researchers perform the treatment by first taking a certain amount of a particular type of the patients own immune cells, called dendritic cells. These cells are messengers of sorts, telling other cells in the immune system what they should be mounting an attack against.
In a New Jersey lab, these cells are fused with a substance called prostatic acid phosphatase -- normally present only on prostate tumor cells.
The result is a treatment that offers a kind of "target practice" for the T-cells, the immune cells responsible for getting rid of threats within the body.
"Essentially, this shows the T-cells where to aim," says Provenge investigator Dr. David Penson, associate professor of urology and preventive medicine at the Keck School of Medicine at the University of Southern California in Los Angeles.
A New Treatment Paradigm?
With the new treatment showing some promise in its first three studies, many may now wonder whether this treatment strategy may be applied to other cancers as well.
Part of the appeal of this therapy is that it is specifically targeted to prostate cancer cells -- and only those cells. Other cells remain untouched, which means that the worst side effects experienced by those in the trials so far have been a few fevers and chills, which are easily treated with Tylenol.
"This drug is very, very non-toxic," Vieweg says.
Penson agrees. "This is not like classic chemo; there is no loss of hair, no sickness associated with it."
Treatment Not For Every Patient
Though initial trials were performed only on men whose prostate cancer was at an advanced stage, the hope is that it will eventually show promise in patients with earlier phases of prostate cancer.
And cancer experts say the need for a new treatment option is growing. But for now, only a few patients with the worst prognoses are considered for participation in trials.
"This is not for every prostate cancer patient -- it is for a select group only, the most desperate patients."
However, researchers also hope the treatment will eventually be used as a front-line therapy, as it may be able to help those experiencing the first stages of prostate cancer as well.