Biologic therapies uses the body's own systems and abilities to fight the cancer or heal healthy tissue after treatment. Most of these therapies take advantage of the body's immune system, either directly or indirectly, to fight cancer or to lessen the side effects that may be caused by some cancer treatments.
- How does the immune system work?
- How do biologic therapies work?
- What are the major types of biologic therapies?
- What are the side effects?
The immune system consists of a complex network of cells and organs. The key cells involved in the immune system are white blood cells which signal, identify, and attack infectious invaders. There are several types of white blood cells, each with their own function including:
- Lymphocytes—concentrated in areas of the body that commonly encounter hostile invaders (stomach and intestines, lungs, and lymph system). Types of lymphocytes include:
- B cells—lead to the production of antibodies that help target tissue that should be destroyed
- Cytotoxic T cells—directly attack infected or cancer cells
- Helper T cells—regulate the immune system's response by signaling other immune system cells
- Natural killer (NK) cells—produce powerful chemical substances that bind to and kill invaders
- Macrophages—surround and digest invaders while stimulating other defense mechanisms
Cells release proteins called cytokines. These cytokines are important communicating factors between cells to help boost the immune system and identify good or bad cells. Cytokines include:
- Colony-stimulating factors
Biologic therapies repair, stimulate, or enhance the body’s response to cancer. Biologic therapies can:
- Eliminate, regulate, or suppress conditions that allow uncontrolled cell growth
- Enhance the immune system to fight the uncontrolled growth of cancer cells
- Make cancer cells more vulnerable to destruction by the immune system
- Change the growth patterns of cancer cells so that they are more like normal cells, and are less likely to spread
- Block or reverse the process that changes a normal or precancerous cell into a cancerous cell
- Enhance the body's ability to repair normal cells that get damaged by other forms of treatment for cancer by chemo- or radiation therapy
- Prevent a cancer cell from spreading to other parts of the body
Biologic therapies are most commonly used either to treat cancer that does not or has not responded to other forms of treatment. They may also be used to treat tumors that may respond to the body’s own immune defenses.
The most common biologic therapies include:
- Interferons (IFN)
- Interleukins (IL)
- Colony-stimulating factors (CSF)
- Monoclonal antibodies (mAb)
IFN occurs naturally in the body. IFN is produced by virally-infected cells and is capable of protecting other cells from infection. Researchers have found that interferons enhance the immune system’s ability to fight cancer cells and act directly on these cells by slowing growth and encouraging normal cell behavior.
There are different types of IFNs, but interferon alpha is used to treat cancer. Currently interferon alpha is used to treat cancers including hairy cell leukemia, Kaposi's sarcoma, and chronic myeloid leukemia (CML).
Like IFNs, ILs occur naturally in the body and can be synthesized in a lab. ILs are named numerically as IL-1 through IL-18.
IL-2 has been the most widely studied in cancer treatment. This type stimulates the growth and activity of many cancer-killing immune cells, including NK cells and cytotoxic T cells. In addition, IL-2 enhances antibody responses.
CSFs do not affect cancer cells directly. Instead, CSFs help stimulate the production of new red blood cells, white blood cells, and platelets. This is important because many cancer treatments can decrease the levels of blood cells, which increases the risk of infection, anemia, and bleeding problems. Stimulating blood cell production can help stimulate the immune system.
Some examples of CSFs include:
- G-CSF and GM-CSF—Increase the number of white blood cells, which reduces the risk of infection. They can also be used to stimulate the production of stem cells in preparation for stem cell or bone marrow transplants.
- Erythropoietin—Increase the number of red blood cells and reduce the need for red blood cell transfusion.
- Oprelvekin—Increase the number of platelets and reduce the need for platelet transfusions.
Monoclonal antibodies (mAbs) are substances that are produced in a lab. The process involves injecting a mouse with cells for a certain type of human cancer. Once injected with the cancer cells, the mouse produces antibodies to fight against the cancer. These mouse antibodies are then combined with other lab cells to create hybrid cells to fight cancer.
MAbs can be used in cancer treatment in a number of ways. They may:
- React with certain types of cancer, to enhance the body's immune response
- Be programmed to act against specific cell growth factors to interfere with the growth of cancer cells
- Be linked to anticancer drugs, radioactive substances, other biologic therapies, or other toxins to tag the cancer cells and alert the immune system to destroy them
- Possibly help destroy cancer cells in bone marrow (during the process of bone marrow transplant)
There are a number of mAbs available, such as:
- Rituximab—used to treat non-Hodgkin's lymphoma
- Trastuzumab—used to treat breast cancer when the tumor expresses excess amounts of a protein called HER-2
- Cetuximab—used to treat colon and rectal cancers, as well as head and neck cancer
- Panitumumab—used to treat colon and rectal cancers
- Bevacizumab—used to treat a certain type of brain tumor, and kidney, colon, rectal, lung, and breast cancers
- Alemtuzumab—used to treat chronic lymphocytic leukemia
- Ipilimumab—used to treat melanoma
The side effects depend on the type of biologic therapy that is used.
At the beginning of therapy, you will most likely experience flu-like symptoms, such as chills, headaches, muscle and joint pain, and discomfort.
Chronic side effects tend to increase in intensity after you have been on IFN therapy for several weeks. Loss of appetite with weight loss and fatigue can be severe enough to limit the dose. Other side effects include:
More common side effects include:
- Flu-like symptoms—chills, fever, fatigue, headache, and muscle pain and joint pain
- Gastrointestinal effects, such as nausea, vomiting, diarrhea, and decreased appetite
Other side effects include:
- Red, dry, or itchy skin, with or without a rash
- Low blood pressure, rapid heart rate, heart arrhythmia, fluid retention, and weight gain
- Confusion, disorientation, drowsiness, lethargy, anxiety, depression, and irritability
- Changes in blood cell counts that can lead to anemia, thrombocytopenia, eosinophilia, lymphopenia
- Problems with kidney function
Severe toxicities are associated with high doses of IL-2.
CSF therapy is generally well tolerated. The side effects are minimal. Bone pain is one of the most commonly reported side effects.
With mAbs, allergic reaction to mouse protein is a major concern. Rarely, the acute reaction can result in anaphylaxis, a severe, sometimes life-threatening, allergic reaction.
More common side effects include:
- Nausea and vomiting
- Difficulty breathing
- Low blood pressure
A delayed toxicity that can occur is called serum sickness. Symptoms of serum sickness include:
- Joint pain
- Swollen glands
- Flu-like symptoms
- Reviewer: Mohei Abouzied, MD, FACP
- Review Date: 03/2015 -
- Update Date: 05/26/2015 -