What is biological therapy?
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. Doctors and researchers have found that the immune system might also be able to both determine the difference between healthy cells and cancer cells in the body, and to eliminate the cancer cells. (By itself, the immune system is not always good at destroying cancer cells; if it were, people would not get cancer.)
Biological therapies are designed to boost the immune system, either directly or indirectly, by assisting in the following:
Stop, control, or suppress the processes that allow cancers to grow
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
Biological therapies can be used alone to treat cancer or can be combined with other treatments such as chemotherapy and radiation therapy.
How can the immune system fight cancer?
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. These are white blood cells, including B cells, T cells, and NK cells.
B cells. Cells that produce antibodies that attack other cells.
T cells. Cells that directly attack cancer cells themselves and signal other immune system cells to defend the body.
Natural killer cells (NK cells). Cells that produce chemicals that bind to and kill foreign invaders in the body.
Monocytes. These are white blood cells that swallow and digest foreign particles.
Dendritic cells. Cells that present the foreign cells to the immune system.
These types of white blood cells--B cells, T cells, natural killer cells, and monocytes--are in the blood and circulate to every part of the body, providing protection from cancer and other diseases. White blood cells secrete two types of substances: antibodies and cytokines. Antibodies respond to harmful substances that they recognize, called antigens. Specific (helpful) antibodies match specific (foreign) antigens by locking together. Cytokines are proteins produced by some immune system cells that attract other immune system cells or that may directly attack cancer cells. Cytokines are messengers that communicate with other cells.
What are the different types of biological therapies?
There are many different types of biological therapies used in cancer treatment.
Biological response modifiers (BRMs) change the way the body's defenses interact with cancer cells. BRMs are produced naturally in the body and 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 substances like nonspecific immunomodulating agents, interferons, interleukins, colony-stimulating factors, monoclonal antibodies, and vaccines:
Nonspecific immunomodulating agents. Nonspecific immunomodulating agents are biological therapy drugs that stimulate the immune system in a general way, 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.
Interferons (IFN). Interferons are a type of biological response modifier that naturally occurs in the body. They are also 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 certain kinds of 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 may also stimulate natural killer cells (NK) cells, T cells, and monocytes--types of white blood cells in the bloodstream that help to fight cancer cells.
Interleukins (IL). Interleukins stimulate the growth and activity of many immune cells. They are proteins (cytokines) that occur naturally in the body, but can also 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 (CSFs). 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 sometimes given, along with chemotherapy, to help boost the immune system. When cancer patients receive chemotherapy, the bone marrow's ability to produce new white blood cells is suppressed, making patients more prone to developing infections. Colony-stimulating factors encourage the bone marrow stem cells to produce white blood cells. With proper cell production, other cancer treatments can continue enabling patients to safely receive higher doses of chemotherapy.
Monoclonal antibodies. Monoclonal antibodies are agents, produced in the laboratory, that bind to specific parts of cancer cells. Some monoclonal antibodies work by tagging cancer cells for destruction by parts of the immune system, while others work by shutting down some function that cancer cells need to survive. Some are linked to anticancer drugs, radioactive substances, or other biological response modifiers. When the antibodies attach to cancer cells, they deliver these poisons directly to the tumor, helping to destroy it. Monoclonal antibody agents generally do not affect healthy cells.
Vaccine therapy. Vaccine therapy is a growing area of cancer research. The idea of vaccine therapy is to get the body's immune system to start attacking the cancer cells in the body. With infectious diseases, vaccines are given before the disease develops. Cancer vaccines, however, are usually given after the disease develops, when the tumor is small. They may also be given to a healthy person before cancer develops, with the hopes of stimulating the immune system to attack viruses that cause cancer. Scientists are testing the value of vaccines in treating many types of cancer. Sometimes, vaccines are combined with other biological therapies.
Are there side effects of biological therapies?
As each person's 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 or all possible side effects of treatment before the treatment begins.
Side effects of biological therapy vary according to the type of therapy given and may include the following:
Loss of appetite
Specifically, interleukins and interferons often cause flulike symptoms, such as fever, chills, aches, and fatigue. Other side effects may include a rash or swelling at the injection site. Interleukins can be associated with low blood pressure and generally require close monitoring in the hospital during infusion. Monoclonal antibodies sometimes cause allergic reactions. Some treatment can cause fatigue and bone pain and may affect blood pressure and the heart.