Immunotherapy and Prostate Cancer
In recent years, researchers have discovered that prostate cancers do have the potential to respond to immunotherapy. Right now, only one immunotherapy treatment is approved by the Food and Drug Administration (FDA).
All other immunotherapy treatment options are available through clinical trials. If you are interested in immunotherapy, talk with your doctor about your options, including a clinical trial.
Types of Immunotherapy
Researchers know the body’s immune system can recognize cancer cells, including prostate cancer. Like many other cancers, prostate cancer is able to evade the immune system by deactivating T cells, the blood cells most responsible for attacking foreign or abnormal cells in our bodies. Provenge® is a FDA approved therapeutic vaccine designed to enhance the immune response to prostate cancer cells by reactivating the T cells.
The vaccine requires a special process and facilities. The first step is that doctors remove immature immune cells from the man with advanced prostate cancer. They do this to get the cells out of the environment that allows the cancer cells to escape the immune response.
They then re-engineer the cells, combining them with a manmade version of PAP, an antigen expressed by 95% of metastatic prostate cancer cells and a factor to help the T-cells grow and mature in the body (GM-CSF).
Once they are returned to the man’s body, the new cells are activated and “trained” to attack the prostate cancer. Provenge® has been shown to extend survival for men with advanced prostate cancer who no longer respond to hormones and chemotherapy.
The side effects of Provenge® are generally mild to moderate and include headache, fatigue, nausea and joint pain. Another advantage to Provenge® is the course of treatment is relatively short—about one month and six treatments long.
As promising as the results of using Provenge® are, it is not for every man with advanced prostate cancer. It is used only for men who have few or no symptoms of their prostate cancer.
There are also only a few special facilities capable of re-engineering the cells and making the vaccine. For that reason, it is not widely available and can be expensive. To learn more about Provenge® and what centers offer this therapy, talk to your doctor.
PROSTVAC is similar to Provenge® in that it uses re-engineered cells to attack prostate cancer cells. This vaccine is targeted to the PSA antigen and is currently being studied in a large, global Phase III trial in men with advanced prostate cancer.
Participants in the trial receive the vaccine either with or without the factor that helps the T cells grow and mature (GM-CSF). PROSTVAC is also being tested with ipilimumab (Yervoy®) with promising results. “Ipi” as it is known is a drug that boosts the body’s immune response against cancer.
GVAX is composed of prostate cancer cells that are irradiated and then engineered to express the factor that stimulates immune cells to grow and replicate—GM-CSF. It is often studied in clinical trials in combination with other immunotherapy drugs such as ipilimumab or with hormone therapy.
GVAX with ipilimumab has shown promising results in men with advanced, hormone resistant prostate cancer. There is also some evidence that it may reduce the risk of recurrence in men with high-risk localized prostate cancers when given with hormone therapy.
The Future of Immunotherapy for Prostate Cancer
Immunotherapy for prostate cancer, especially cancers that have spread and become resistant to other treatments, is a rapidly emerging approach to treatment. Many treatments are still being studied and are available only through clinical trials.
As the understanding of the dynamic relationship between cancer cells and the immune system deepens, there will be increasing opportunities to develop new therapies using that knowledge to help improve the outcomes for men with prostate cancer.