Biological therapy (also called immunotherapy, biological response modifier therapy or biotherapy) uses the body’s immune system to fight cancer. The cells, antibodies and organs of the immune system work to protect and defend the body against foreign invaders, such as bacteria or viruses. Physicians and researchers have found that the immune system also might be able to determine the difference between healthy cells and cancer cells in the body, and to eliminate the cancer cells.
Biological therapies are designed to boost the immune system, either directly or indirectly, by assisting in the following:
- Making cancer cells more recognizable by the immune system, and therefore more susceptible to destruction by the immune system
- Boosting the killing power of immune system cells
- Changing the way cancer cells grow, so that they act more like healthy cells
- Stopping the process that changes a normal cell into a cancerous cell
- Enhancing the body’s ability to repair or replace normal cells damaged or destroyed by other forms of cancer treatment, such as chemotherapy or radiation
- Preventing cancer cells from spreading to other parts of the body
The immune system includes different types of white blood cells, each with a different way to fight against foreign or diseased cells, including cancer:
- Lymphocytes– white blood cells, including B cells, T cells and NK cells:
- B cells produce antibodies that attack other cells.
- T cells directly attack cancer cells themselves and signal other immune system cells to defend the body.
- Natural killer cells produce chemicals that bind to and kill foreign invaders in the body.
- Monocytes – white blood cells that swallow and digest foreign particles.
These types of white blood cells — B cells, T cells, natural killer cells and monocytes — are in the blood and thus circulate to every part of the body, providing protection from cancer and other diseases.
Cells secrete two types of substances: antibodies and cytokines. Antibodies respond to (harmful) substances, called antigens that they recognize. Specific (helpful) antibodies match specific (foreign) antigens by locking together. Cytokines are proteins produced by some immune system cells and can directly attack cancer cells. Cytokines are “messengers” that “communicate” with other cells.
There are many different types of biological therapies used in cancer treatment, including the following:
- Nonspecific immunomodulating agents – biological therapy drugs that stimulate the immune system, causing it to produce more cytokines and antibodies to help fight cancer and infections in the body. Fighting infection is important for a person with cancer.
- Biological response modifiers– change the way the body’s defenses interact with cancer cells. BRMs are produced in a laboratory and given to patients to:
- Boost the body’s ability to fight the disease.
- Direct the immune system’s disease-fighting powers to disease cells.
- Strengthen a weakened immune system.
BRMs include interferons, interleukins, colony-stimulating factors, monoclonal antibodies, cytokine therapy and vaccines:
- Interferons – a type of biological response modifier that naturally occurs in the body. They also are produced in the laboratory and given to cancer patients in biological therapy. They have been shown to improve the way a cancer patient’s immune system acts against cancer cells. Interferons may work directly on cancer cells to slow their growth, or they may cause cancer cells to change into cells with more normal behavior. Some interferons also may stimulate natural killer cells cells, T cells and macrophages — types of white blood cells in the bloodstream that help to fight cancer cells.
- Interleukins – stimulate the growth and activity of many immune cells. They are proteins (cytokines) that occur naturally in the body, but also can be made in the laboratory. Some interleukins stimulate the growth and activity of immune cells, such as lymphocytes, which work to destroy cancer cells.
- Colony-stimulating factors – are proteins given to patients to encourage stem cells within the bone marrow to produce more blood cells. The body constantly needs new white blood cells, red blood cells and platelets, especially when cancer is present. CSFs are given along with chemotherapy to help boost the immune system. When cancer patients receive chemotherapy, the bone marrow’s ability to produce new blood cells is suppressed, making patients more prone to developing infections. Parts of the immune system cannot function without blood cells; thus, colony-stimulating factors encourage the bone marrow stem cells to produce white blood cells, platelets and red blood cells. With proper cell production, other cancer treatments can continue enabling patients to safely receive higher doses of chemotherapy.
- Monoclonal antibodies – are agents, produced in the laboratory, that bind to cancer cells. When cancer-destroying agents are introduced into the body, they seek out the antibodies and kill the cancer cells. Monoclonal antibody agents do not destroy healthy cells.
- Cytokine therapy – uses proteins (cytokines) to help your immune system recognize and destroy those cells that are cancerous. Cytokines are produced naturally in the body by the immune system, but also can be produced in the laboratory. This therapy is used with advanced melanoma and with adjuvant therapy (therapy given after or in addition to the primary cancer treatment). Cytokine therapy reaches all parts of the body to kill cancer cells and prevent tumors from growing.
- Vaccine therapy – is still an experimental biological therapy. The benefit of vaccine therapy has not yet been proven. With infectious diseases, vaccines are given before the disease develops. Cancer vaccines, however, are given after the disease develops, when the tumor is small. Scientists are testing the value of vaccines for melanoma and other cancers. Sometimes, vaccines are combined with other therapies such as cytokine therapy.
As each person’s individual medical profile and diagnosis is different, so is his or her reaction to treatment. Side effects may be severe, mild or absent. Be sure to discuss with your cancer care team any and all possible side effects of treatment before the treatment begins.
Side effects of biological therapy, which often mimic flu-like symptoms, vary according to the type of therapy given and may include the following:
- Loss of appetite
Specifically, cytokine therapy often causes fever, chills, aches and fatigue. Other side effects include a rash or swelling at the injection site. Therapy can cause fatigue and bone pain, and may affect blood pressure.