What is biological therapy?
Biological therapy is also called immunotherapy, biological response modifier (BRM) therapy, or biotherapy. It 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. Researchers have found that the immune system can be boosted to better find the differences between healthy cells and cancer cells in the body, and to kill the cancer cells.
Biological therapies are designed to boost the immune system, either directly or indirectly, by:
Stopping, controlling, or suppressing the processes that allow cancers to grow
Making cancer cells more recognizable by the immune system, as a result, more likely to be destroyed by the immune system
Boosting the killing power of immune system cells
Reprogramming natural immune cells so they are trained to fight cancer cells
Preventing cancer cells from spreading to other parts of the body
Biological therapies can be used alone to treat cancer. They can also 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 make antibodies that tag foreign or abnormal cells so other parts of the immune system can destroy them.
T cells directly attack cancer cells and signal other immune system cells to defend the body.
Natural killer cells (NK cells) find, bind to, and kill foreign invaders or damaged cells in the body.
Macrophages are white blood cells that swallow and digest foreign particles and signal other immune systems cells to do it.
Dendritic cells present the foreign cells to the immune system.
These types of white blood cells—B cells, T cells, natural killer cells, and macrophages—are in the blood and circulate to every part of the body, providing protection from cancer and other diseases.
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 made naturally in the body and in a laboratory. They are 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 weak immune system
BRMs include substances like nonspecific immunomodulating agents, colony-stimulating factors (CSFs), monoclonal antibodies, and vaccines:
Nonspecific immunomodulating agents
Nonspecific immunomodulating agents are biological therapy drugs that stimulate the immune system in a general way. These 2 types are commonly used to treat cancer.
Interferons (IFN). Interferons are a natural type of BRM in the body. They are also made in the lab and given to cancer patients in biological therapy. They 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 to fight cancer cells.
Interleukins (IL). Interleukins stimulate the growth and activity of many immune cells. They are proteins (cytokines) that happen naturally in the body. They can also be made in the lab. 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 given to patients to encourage stem cells within the bone marrow to make more blood cells. CSFs are sometimes given, often along with chemotherapy, to help boost the immune system. Chemotherapy slows the bone marrow's ability to make new white blood cells. This makes patients more likely to develop infections. CSFs trigger the bone marrow stem cells to make white blood cells.
Monoclonal antibodies are agents, made in the lab, that bind to specific parts of cancer cells. Some monoclonal antibodies work by tagging cancer cells for destruction by parts of the immune system. 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. Then when the antibodies attach to cancer cells, they deliver these poisons directly to the tumor. This helps to destroy it.
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. But, cancer vaccines are usually given after the disease develops, when the tumor is small. 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 treatment starts.
Side effects of biological therapy vary according to the type of therapy given. They tend to be different from chemotherapy side effects and may include the following:
Specifically, interleukins and interferons often cause flu-like symptoms. These include 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 need close monitoring in the hospital during infusion. Monoclonal antibodies sometimes cause allergic reactions during the treatment or infusion.
Talk with your doctor about what side effects you should watch for and what to do if you have side effects.