In order for the immune system to fight off foreign invaders, it has to learn to recognize what’s normal and what’s not normal. Unfortunately, because cancer cells start out as normal healthy cells, the immune system never has a chance to learn to distinguish between the normal cell and the cancer cell.
Unlike preventive vaccines, which are designed to teach the immune system to develop a way to fight off a specific virus should it come into contact with that same virus again, therapeutic vaccines stimulate the immune system to recognize and fight certain proteins specific to cancer cells. Each of the therapeutic vaccines currently being tested in men with advanced prostate cancer works in a slightly different fashion, but all are designed to harness the immune system’s ability to fight off disease and teach it to fight off prostate cancer cells. One such vaccine, sipuleucel-T (Provenge) was recently approved by the FDA for prostate cancer.
This immune therapy is FDA-approved for men with prostate cancer that has spread outside of the prostate and is resistant to standard hormone treatment. This treatment is meant for men with minimal or no pain, and is most commonly given before chemotherapy, although it appears to be effective in some men even after chemotherapy.
This treatment is process involves filtering out your own immune cells, stimulating them to fight prostate cancer in a lab, and then giving those cells back to you. More specifically, the first step is called leukopheresis, a process that filters your blood and removesthe disease-fighting white blood cells. These cells are then stimulated in a laboratory externally with a prostate cancer protein called PAP and boosted with an immune protein called GM-CSF. These stimulated cells are then given back to you as an intravenous infusion, much like a blood transfusion. This process is repeated every 2 weeks for a total of 3 treatments. The goal is to stimulate your own immune system to fight the cancer cells. This immunotherapy does not lower the PSA, treat symptoms, or delay disease progression – however, importantly, it has been shown to prolong life. There are ongoing studies attempting to clarify exactly how this treatment works.
This treatment can only be given in certain centers, and you should discuss with your doctor whether this treatment is appropriate for you and, if so, where you can receive it.
The side effects of sipuleucel-T are usually limited to the few days after infusion of the stimulated cells. You can sometimes experience a flu-like illness with fever, chills, nausea, and bone/muscle aches. This generally resolves within 3 days and can be treated with acetaminophen.
Terms to know from this article:
prostate-specific antigen (PSA): A substance produced by the prostate that may be found in an increased amount in the blood of men who have prostate cancer, benign prostatic hyperplasia, or infection or inflammation of the prostate.