The co-authors of Invasion of the Prostate Snatchers, blog alternate posts weekly. We invite you to post your comments.

Tuesday, March 26, 2013

What is the Most Exciting New Treatment for Prostate Cancer?


As a medical oncologist specializing in prostate cancer, the question I am asked by patients almost daily is, “What new treatments are coming for prostate cancer?” Fortunately, there are so many new developments I am able to give answers that vary depending on the stage (or Shade, to use PCRI terminology) of the person asking, since they are usually interested in developments relevant to their specific situation.

However, if I am asked a slightly different question—“What type of new technology has the greatest potential for saving lives?”—my answer will always be the same for every patient: Immune therapy.  Let me explain why.
Before the intricate complexity of cancer biology was recognized—through the amazing work of thousands of biochemical researchers—people were hoping a single magic bullet could be discovered that would cure cancer.  That hope has been dashed because we now know there are innumerable variations of what we call “cancer.” Waiting for the discovery of a single type of treatment universally effective against all types of cancer is quite naive.
However, there is one intrinsic capacity in our bodies that successfully parries millions of different attacks on our health: the immune system. Therefore, if a cure for the myriad of different cancer types exists, it will probably result from successfully harnessing this incredible system.
One fallacy believed by almost all patients is that their cancer is the result of a weak immune system. Their logic is that their immune system somehow has to be weak considering that the cancer has not been kept under control. Actually, if we are going to speak figuratively about the immune system, the problem is better characterized as an issue of blindness rather than one of weakness.
Early success in using the immune system to overcome scourges such as polio caused cancer researchers to study vaccine type methods for stimulating the immune system to attack cancer,unfortunately with only modest results. The problem is that cancer cells have mechanisms that enable them to hide from the immune system.
The fairly recent discovery of this capacity for cancer to cloak itself represents both good news and bad. Without a specific target to attack, simply making the immune system “stronger” is useless. The good news is that a properly directed immune system can and will eradicate cancer.
Prostate cancer is one of the few types of cancer for which an immune therapy has been approved by the FDA. Dendreon, the company that manufactures the immune treatment called Provenge, has developed technology to remove and purify dendritic cells, the specific immune cells in the body that can detect cancer.  Once in the lab the dendritic cells are “force fed” with a cancer-specific protein. After being reinjected into the body, these invigorated immune cells recruit additional cells of the immune system that specifically focus their attack on the cancer cells displaying that cancer-specific protein.
Double-blind, placebo-controlled trials show Provenge slows cancer progression and prolongs survival just as well or even better than other standard treatments such as chemotherapy or second-line hormonal therapy. None of these treatments consistently eradicate cancer.  They do, however, act to keep it in check for a period of time.
To obtain better results the next logical step is combining one form of immune therapy—Provenge—with some other immune therapy with the hope of further enhancing the anti-cancer effect. My next blog will discuss a new study we are conducting in my clinical practice at Prostate Oncology Specialists using Provenge in combination with “Yervoy,” a monoclonal antibody from Bristol-Myers Squib. Generically Known as ipilimumab, Yervoy is an FDA-approved immune treatment shown to prolong life in people with metastatic melanoma.  Yervoy functions by “taking the brakes” off the immune system.
Sound exciting?  We think so.               

1 comment:

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