One of the most exciting new directions for dealing with cancer is the field of immunotherapy. The word itself suggests using the body’s own defenses against disease as a way of healing illness. The idea is certainly not new, but I want to offer some general information and then a couple of specific adaptations of immunotherapy for use against prostate cancer.
According to the American Cancer Society, there are 3 types of immunotherapy[i]:
- Monoclonal antibodies are manmade versions of immune system proteins that can go after certain parts of cancer cells.
- Cancer vaccines can be used to stimulate an immune system response to certain diseases.
- Non-specific immunotherapies are not directed at a particular disease or condition, but generally boost the immune system to work more effectively.
The immune system itself is complex. It has several components, each of which has a part to play:
- Antibodies, white blood cells, and other proteins and chemicals that can recognize, attack and destroy foreign bodies such as bacteria, viruses, and cancer cells.
- The thymus gland, which makes T cells.
- The lymph system, which circulates lymphatic fluid throughout the body, sweeping up foreign particles. In turn, the fluid is filtered by the lymph nodes, where the particles are destroyed by special white blood cells called lymphocytes.
- Bone marrow, which produces red and white blood cells.
- Dendritic cells, which capture antigens (proteins on the surface of cells) to identify threats, and relay that information to T cells which can then destroy it upon encounter.
Recent discoveries about T cells helped uncover the ways in which the body normally puts the “brakes” on these cells, with their power to attack and destroy. Scientists reasoned that when a patient has a particularly aggressive cancer, such as melanoma—the most dangerous skin cancer—taking the brakes off of T cells would liberate them to wage war against the disease in a more concerted fashion. Researchers began work on drugs that would turn off the braking mechanism. One drug, ipilumilab, proved so successful at extending life for melanoma patients in clinical trials that in 2011 it was approved for treating metastatic melanoma.
According to the Cancer Research Institute, “In immunotherapy, prostate cancer has been at the vanguard.”[ii] You may already know about Provenge®(developed by Dendreon), the first therapeutic vaccine approved for any type of cancer. It harnesses the power of dendritic cells to trigger an immune response against a specific antigen produced by most prostate cancer cells. Ways to improve its effectiveness are being tested. Other prostate cancer vaccines are also in development.
Another immunotherapy area of research against prostate cancer is called checkpoint inhibitors/immune modulators. An example is clinical studies that combine ipilumilab with another drug in an effort to free up immune system components to target prostate cancer cells that may be circulating in the body, or have begun to form solid tumors outside of the prostate.
Finally, a technique called adoptive cell therapy involves removing a prostate cancer patient’s T cells, treating them with chemicals or modifying them genetically to invigorate them, and returning them to the patient’s body. Clinical trials are underway.
My particular interest in immunotherapy has to do with its potential use in conjunction with focal therapy. No one knows all the reasons why an otherwise healthy person develops prostate cancer, though factors like heredity or exposure to environmental toxins might be factors. When we treat a prostate tumor with focal laser ablation (FLA) we want to provide that patient with resources so he can fortify his immune system—a modified form of non-specific immunotherapy. Much research points to the power of correct nutrition, exercise, stress management, supplements, etc. to create positive genetic change, minimizing a person’s risk of recurrence. I look forward to the day when, in addition to these lifestyle changes, a simple prostate cancer vaccine will be available to reinforce the effectiveness of FLA. These three things—focal treatment, personal immune empowerment, and a vaccine—may prove to be the crucial ingredients in a long and cancer-free life following treatment.