Prostate Cancer Vaccine May Improve Survival
Provenge Extends Life When Other Treatments Fail
The vaccine is still experimental and not yet available outside of clinical trials. Dendreon - the vaccine's maker - says the vaccine is being "fast-tracked" through the FDA. But it is still not likely to be up for approval until 2006 at the earliest. Results from additional trials are not expected until late 2005.
The vaccine itself was developed from each individual patient's cells, a process that began with a blood donation. The goal here was to "teach" the body to recognize and attack growing tumor cells.
As Small explains, the cells were processed to "enrich" the power of the patients' own immune cells to "search out target proteins that reside on the surface of 90%-95% of all prostate cancers." While most men can be successfully treated with surgery, radiation, and hormone therapy, for some, these treatments are simply not enough. Currently the only drug approved by the FDA for the treatment of advanced prostate cancer is Taxotere. But as promising as the new vaccine approach appears to be, experts point out it's still too early to determine the true benefit that may one day come from the vaccine.
Kantoff points out the study was relatively small, including only 127 men -- compared with a thousand or more who frequently participate in a single chemotherapy trial.
As a result, Kantoff says the positive findings could have been the result of "unforeseen biologic differences in the two groups." In this instance, factors related to each man's cancer and overall health might have actually been responsible for the outcome currently being credited to the prostate cancer vaccine.
The only way to know for sure, he says, is to duplicate the results in a much larger clinical trial --something the researchers are hoping to accomplish.
Still, Kantoff says the findings represent a major step forward in a potentially new and perhaps less toxic treatment for prostate cancer.
"The magnitude of the impact of this trial is remarkably large," he says, indicating that, if proven in larger trials, it could dramatically change prostate cancer treatment.