Using the Immune System To Treat Non-Muscle-Invasive Bladder Cancer
Immunotherapy – also referred to as biological therapy, biotherapy or biological response modifier therapy – is a relatively new treatment for cancer. These therapies use the body’s immune system, either directly or indirectly, to fight cancer.
The immune system is a complex network of cells and organs that work together to defend the body against attacks by "foreign," or "non-self," invaders. This network is one of the body’s main defenses against disease. It works against disease, including cancer, in a variety of ways. For example, the immune system may recognize the difference between healthy cells and cancer cells in the body and work to eliminate those that become cancerous.
Cancer may develop when the immune system breaks down or is not functioning adequately. Biological therapies are designed to repair, stimulate, or enhance the immune system’s responses.
Nonspecific immunomodulating agents are substances that stimulate or indirectly augment the immune system. Often, these agents target key immune system cells and cause secondary responses such as increased production of cytokines and immunoglobulins. BCG is an immunomodulating agent commonly used in the treatment of superficial bladder cancer following surgery to remove the tumor(s)..
Biological Response Modifiers (BRMs)
Some antibodies, cytokines, and other immune system substances can be produced in the laboratory for use in cancer treatment. These substances are often called biological response modifiers (BRMs). They alter the interaction between the body’s immune defenses and cancer cells to boost, direct, or restore the body’s ability to fight the disease. BRMs include interferons, interleukins, colony-stimulating factors, monoclonal antibodies, and vaccines.
Researchers continue to discover new BRMs, learn more about how they function, and develop ways to use them in cancer therapy. Biological therapies may be used to:
- Stop, control, or suppress processes that permit cancer growth;
- Make cancer cells more recognizable, and therefore more susceptible, to destruction by the immune system;
- Boost the killing power of immune system cells, such as T cells, NK cells, and macrophages;
- Alter cancer cells’ growth patterns to promote behavior like that of healthy cells;
- Block or reverse the process that changes a normal cell or a precancerous cell into a cancerous cell;
- Enhance the body’s ability to repair or replace normal cells damaged or destroyed by other forms of cancer treatment, such as chemotherapy or radiation; and
- Prevent cancer cells from spreading to other parts of the body.
Interferons are types of cytokines that occur naturally in the body. They were the first cytokines produced in the laboratory for use as BRMs. There are three major types of interferons—interferon alpha, interferon beta, and interferon gamma; interferon alpha is the type most widely used in bladder cancer cancer treatment.
Researchers have found that interferons can improve the way a cancer patient’s immune system acts against cancer cells. In addition, interferons may act directly on cancer cells by slowing their growth or promoting their development into cells with more normal behavior. Researchers believe that some interferons may also stimulate NK cells, T cells, and macrophages, boosting the immune system’s anticancer function.
Researchers are now conducting trails exploring the combination of interferon alpha 2b with low dose BCG, and it is proving to be an effective treatment for those who have recurred after initial BCG treatment. More info: Interferon.
Source: NCI Fact Sheet 7.2