April 15, 2009
Antidote: FDA took wrong stance on Provenge for prostate cancer
I haven't covered prostate cancer in this space before, in part because the choices, though controversial, have been somewhat static for some time. The number two cancer killer of men has always been difficult to diagnosis, and even more difficult to treat. The gold standard operation, a radical prostatectomy, now comes standard with nerve bundle sparing techniques in an attempt to preserve potency, with varying amounts of success. Surgery, after all, is an art, and in many centers, robotic techniques are on the rise and even threaten to replace the scalpel-only approach. Though the technology of robotics can lead to a smaller incision, (doctors manipulate the robot from computer screens) there is as yet no evidence that this actually reduces the side effects or improves outcome.
Another new procedure that is currently the range in places like Mexico and is now being used here in the US is High Intensity Focus Ultrasound. There are many small manufacturers who make this equipment and there are more than 100 centers worldwide that offer the treatment, but though it may prove useful for early stage cancers, the jury is out about its potential use for more extensive or aggressive prostate cancers.
The question of what to do if you have prostate cancer remains controversial. Decisions depend on age, desire to maintain potency, as well as openness to various radiation options, (external beam, radiation seeds), with their own group of side effects.
If the initial treatments don't work, and the cancer escapes the prostate, we are left with testosterone lowering hormonal therapies and debilitating chemotherapies that often fail. Now along comes a new approach - an immunological vaccine. Dendreon Corp is studying the use of an immunological vaccine (produced by using the patient's own cancer cells), for use in advanced prostate cancer. In a study (phase III clinical trial) of 512 men who have not benefited from drugs that lower testosterone, the company is reporting improved survival numbers with use of the vaccine.
This is exciting news, and expect it to be backed up by a presentation to the American Urological Association later this month. We are entering a world of genetic signatures, multiple genetic determiners of cancer with targeted therapies, and directed immune therapies such as this one (the vaccine is known as Provenge).
The only negative? An advisory panel of doctors recommended in March 2007 that the FDA approve Provenge, based on favorable efficacy and safety results from an earlier Phase III study. But the FDA declined, deciding to wait until data from this study (known as IMPACT) confirmed earlier results.
The FDA may end up with egg on its face for waiting. This treatment looks like a winner.
Marc Siegel, MD, is an internist and professor of medicine at New York University and the author of False Alarm: The Truth About the Epidemic of Fear