What is immunotherapy?
Immunotherapy uses your body’s immune system to fight prostate cancer cells. It’s one of several treatment options if your cancer has returned after you have:
Immunotherapy is often used along with another type of cancer treatment, such as radiation therapy or hormone therapy.
Immunotherapy is an area of active research. Because it uses your own immune system to fight disease, it usually has fewer side effects than other treatments.
Only one immunotherapy agent is currently approved for the treatment of prostate cancer. The agent is a vaccine called sipuleucel-T (Provenge). If you’re interested in other immunotherapy options, talk with your doctor about participating in a clinical trial.
Keep reading to learn more about immunotherapy for the treatment of prostate cancer.
How does immunotherapy work?
Immunotherapy works by triggering your immune system to respond or stay active. Your immune system is your body’s way to fight infection. Immunotherapy also blocks proteins that prevent the immune system from doing its job.
The immune system
Your immune system consists of tissues, organs, and cells throughout your body. Its purpose is to fight harmful substances that are foreign to your body, like:
- cancer cells
These harmful substances are called antigens. They may be found at the site of a wound, infection, or cancerous tumor. White blood cells are part of your immune system. They travel to these sites and fight the antigens with chemicals produced by the blood cells.
When you have cancer, your immune system has failed to effectively attack the cancer cells. Researchers don’t know exactly why your immune system stops protecting you from cancer cells. Either the tumor cells or the cells of your immune system may have the ability to turn off the immune response.
Immunotherapy is designed to help your immune system work properly. The therapy triggers your immune system to attack antigens or helps your immune system work more effectively.
Are you a good candidate?
You may be a candidate to receive immunotherapy treatment for your prostate cancer if:
- your prostate cancer has metastasized, or spread outside your prostate gland
- you have castrate-resistant prostate cancer and your PSA levels continue to rise
- your cancer has returned after you’ve had radiation treatment or a radical prostatectomy
- your life expectancy is greater than six months
- you either have no symptoms or your symptoms are minor
Types of immunotherapy
Immunotherapy is an umbrella term for a number of therapies that use your immune system to fight cancer.
You may be familiar with vaccines that protect you from contracting diseases. Therapeutic vaccines are different from other vaccines. Instead of protecting you from developing a disease, they are used to treat existing disease.
Therapeutic cancer vaccines activate T cells, which are white blood cells that destroy cancer cells. They also may spur your immune system to produce more antibodies. As with preventive vaccines, therapeutic vaccines contain an antigen that’s usually injected into your system.
The first therapeutic vaccine for prostate cancer, sipuleucel-T, was introduced in 2010. It’s currently the only FDA-approved immunotherapy treatment for prostate cancer.
Sipuleucel-T is used to treat cancer that has metastasized, or spread beyond the prostate gland. It uses cells from your immune system that have been sent to a laboratory to be cultured with a protein that stimulates the immune system.
Most men tolerate sipuleucel-T infusions better than traditional types of treatment like chemotherapy or radiation therapy. The most common side effects are:
Immune checkpoint inhibitors
Cancer cells are mutations of your body’s own cells. Cancer cells send signals to proteins in your immune cells, called PD-1 and CTLA-4 receptors. These signals trick your body into thinking the cells are normal. This is why your immune system doesn’t recognize them as invaders and doesn’t stop them from dividing and growing.
Immune checkpoint inhibitors disrupt the signals cancer cells send to PD-1 and CTLA-4 receptors. Your immune system can then recognize that the cancer cells are invaders and begin to fight them.
Immune checkpoint inhibitors are given intravenously.
Oncolytic virus therapy
Oncolytic virus therapy uses viruses to carry modified genes to tumor cells in your body. The modified genes cause the tumor cells to self-destruct and trigger your body’s immune system to go on the attack. Oncolytic virus therapy is sometimes called suicide gene therapy because it causes cancer cells to destroy themselves.
Oncolytic virus therapy is often used along with radiation therapy or chemotherapy. It may also enhance the effects of these therapies. Oncolytic virus therapy is given intravenously.
Adoptive cell therapy
Adoptive cell therapy uses white blood cells from your body to help your immune system fight cancer. The while blood cells are removed from your body, grown in a laboratory, and then returned intravenously to your blood stream. There are different approaches to adoptive cell therapy, including:
- selecting only white blood cells with the greatest ability to fight tumor
- genetically modifying white blood cells to attack specific cancer cells in your body
Antibodies, also called immunoglobulins, are proteins produced by the white blood cells of your immune system when antigens are present. Antibodies stick to the antigens and help destroy the cancer cells.
Monoclonal antibodies are created by researchers to target specific antigens on cancer cells. They are used to treat cancer in several different ways.
- Naked monoclonal antibodies can boost the immune system’s response by signaling the presence of the cancer cells, targeting immune system checkpoints, or blocking antigens on the cancer cells.
- Conjugated monoclonal antibodies are loaded with chemotherapy drugs or radioactive particles. The antibodies then take the matter directly to the targeted antigen.
- Bispecific monoclonal antibodies also carry cancer-fighting agents to cells, but they can target two antigens at once.
Some side effects are associated with monoclonal antibodies, but they are usually less severe than with chemotherapy drugs.
Questions for your doctor
If you want to know more about immunotherapy, or if your doctor has recommended it, here are some questions you may want to ask your doctor:
- What are the goals for my treatment?
- What treatment options are available to me?
- What are the pros and cons of each option?
- What clinical trials for immunotherapy are most suitable for me?
- What will my costs be if I participate in a clinical trial?
- What are my responsibilities if I take part in a clinical trial?
- What side effects might I experience?
- How is treatment likely to affect my daily life?
Immunotherapy is a dynamic and promising area of research. It’s been effective in treating a number of different kinds of cancer. However, immunotherapy for the treatment of prostate cancer is still in its infancy. Only sipuleucel-T has been approved by the FDA. Other kinds of immunotherapy for prostate cancer are only available if you participate in a clinical trial.