Johns Hopkins Health Alert
What’s Next for Provenge?
The U.S. Food and Drug Administration's (FDA's) approval of sipuleucel-T (Provenge) -- the first vaccine for the treatment of cancer -- marks an important milestone in the war against prostate cancer. Provenge doesn't prevent prostate cancer (in the sense that most traditional vaccines prevent disease), or cure it or even slow its spread. But it does prolong life in some men with advanced prostate cancer. The extra time, slightly more than four months, is modest, at best, but important because it is proof that a cancer vaccine to boost the immune system can prolong life, suggesting that future vaccines might be even better.
Unlike traditional vaccines, this type of vaccine, also called cancer immunotherapy, is designed to help a person's immune system recognize its own cancerous cells as foreign. Once the cancer cells are perceived as intruders, the person's immune system can mount an attack against them. However, this is particularly challenging with prostate cancer because a man typically has had the disease for several years before it metastasizes. During that period, his immune system has seen the cancer but has grown complacent.
Provenge is approved only for men with advanced prostate cancer who have not responded to other treatments like hormonal therapy and are experiencing few or no symptoms. While the FDA's approval of Provenge is a victory, it is not the end of the fight. Researchers are already studying a number of ways to improve the vaccine's effectiveness.
For example, investigators at Johns Hopkins have found that combining Provenge with androgen deprivation therapy increases the chances of stopping prostate cancer early on. Similarly, investigators have found that combining Provenge with radiation therapy also appears to have a synergistic effect.
Provenge is also being tested in several other clinical trials, including a phase 3 study called Provenge Treatment and Early Cancer Treatment (PROTECT). This study involves men with early-stage, nonmetastatic prostate cancer. Many experts believe that immunotherapy may be most effective in men who have earlier-stage disease.
Newer vaccines also are under development. In one phase 2 study, a vaccine called Prostvac prolonged median survival by 8.5 months. However, like Provenge, Prostvac failed to improve time to disease progression. If Prostvac makes it through the FDA approval process, it promises to be cheaper than Provenge, since it does not have to be customized for each patient and will be available "off the shelf."
Posted in Prostate Disorders on September 8, 2011
Medical Disclaimer: This information is not intended to substitute for the advice of a physician. Click here for additional information: Johns Hopkins Health Alerts Disclaimer
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