|“We hope and believe that men with advanced prostate cancer are going to see greater longevity and a better quality of life [with immunotherapy]. Even now, immunotherapy is a good option for men who have advanced prostate cancer, and we’re going to see the popularity increase as time goes on.” –Dr. Scholz|
The immune system is the checks and balances system of the body. The immune system can detect what is normal or abnormal. It finds and attacks the cells that register as abnormal and passes by those that register as normal.
There are some cells, such as cancer cells, that can slip undetected through the immune system. Therefore, they are able to reproduce and spread. Immunotherapy boosts the immune system so it can recognize and target these cells.
PROVENGE (the only FDA approved immunotherapy for prostate cancer) has faced criticism because it doesn’t typically affect PSA and there are few side effects. People worry those are indicators that it doesn’t have a great effect on prostate cancer. But, studies have shown that immunotherapy does indeed improve survival for men with prostate cancer. Studies where they’ve given PROVENGE to men with rising PSA after surgery demonstrate that while PSA did not immediately drop, the rate of PSA rise was slower and it did ultimately prolong life.
Types of Immunotherapy:
- FDA approved for metastatic castration-resistant prostate cancer.
- Cells removed from the patient’s blood are mixed with a molecule present on prostate cancer cells, prostatic acid phosphatase (PAP), and Leukine.
- This makes the cells more aware of PAP and once the mixture is infused back into the patient, the immune system is able to recognize and destroy the prostate cancer throughout the body.
- FDA approved to counteract immune-suppressing effects of chemotherapy (Off-label for prostate cancer).
- Requires daily injection, not as convenient as other immunotherapy options.
- Checkpoint Inhibitors
- Checkpoints make sure that the immune system doesn’t overreact and start destroying the healthy systems of the body. They regulate the immune system to prevent overactivity (lupus, rheumatoid arthritis, etc.). Immune checkpoints are often referred to as the “brakes” of the immune system.
- The checkpoint inhibitors “take the breaks off the immune system,” revving it up so it can identify and destroy the cancer cells that were once passing through undetected.
- The following are FDA approved for other cancers, but used as off-label for prostate cancer. There are ongoing trials examining checkpoint inhibitors in combination with other immunotherapies.
- The Abscopal Effect
- Radiation can also stimulate the immune system, this is called the abscopal effect.
- When a beam of radiation damages the prostate cancer cells, the immune system is able to “see” the abnormal cells and once it knows what it’s looking for it is able to seek and destroy other prostate cancer cells throughout the body.
- The abscopal effect generally works best with SBRT radiation.
The Future is Bright:
There is a lot of promise for the future of immunotherapy and prostate cancer. Using immunotherapy in combination may be game changing for prostate cancer. For example, PROVENGE in combination with spot radiation and ancillary KEYTRUDA may be a promising way to enhance the immune system even further. Keep an eye on clinicaltrials.gov for upcoming and current clinical trials for immunotherapy and prostate cancer.
Breakthroughs in Radiation Podcast: https://soundcloud.com/prostate-oncology/breakthroughs-in-radiation
The Key to Prostate Cancer: 30 Experts Explain 15 Stages of Prostate Cancer: keytopc.com
Take the prostate cancer staging quiz: keytopc.com
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