Also called: Biological Response Modifier Therapy, Cancer Immunotherapy, BRM Therapy, Biotherapy
Biological therapy is a form of treatment that uses the body’s immune system to fight cancer. The therapy can work either directly or indirectly to enhance, repair or stimulate the immune system’s response to cancer. Certain types of biological therapy also may be used to reduce the side effects of cancer treatments such as chemotherapy.
Biological therapy differs from chemotherapy in that chemotherapy drugs directly attack cancer cells, while biological therapy drugs (also called biological response modifiers) help the body’s immune system to fight cancer.
Some drugs, such as interferons, work with the immune system and act directly on the cancer cells as well. Other drugs, such as colony-stimulating factors (CSF) do not work directly on cancer cells. Instead, these agents work to increase blood cell production impaired by cancer or cancer therapy.
Experts are unsure exactly how biological therapy works, but speculate that it may:
- Stop or slow cancer cell growth
- Help the immune system recognize and destroy cancer cells
- Prevent cancer from spreading throughout the body
In some cases, biological therapy may be the only treatment used to fight a patient’s cancer. In other cases, it may be used in combination with other treatment such as surgery, chemotherapy or radiation therapy.
Biological therapy is most often used in clinical trials, and has been used to treat a number of cancers, including:
- Cancers of the blood (leukemias)
- Breast, ovarian and colon cancer
- Kaposi’s sarcoma
- Lung cancer
- Pancreatic cancer
- Colorectal cancer
- Kidney cancer
While biological therapy has shown great benefits in treating some cancers, like most treatments, it may cause side effects. These can include a rash or swelling at the injection site, flu-like symptoms and fatigue. The side effects are usually related to increased stimulation of the immune system and vary according to the type of treatment. The most common side effects include flu-like symptoms (e.g. fever, chills, nausea), fatigue and loss of appetite. Biological therapy is relatively new and there is limited information about the long-term effects of the treatments.
About biological therapy
Biological therapy works in several different ways to treat cancer. Some agents stimulate the body’s immune system to recognize the difference between healthy cells and cancer cells. Once the cancer cells have been identified, the immune system works to destroy the cancer.
Other biological therapies use agents that work directly on the cancer cells by slowing their growth or promoting their development into cells with more normal behavior. In addition, some biological therapies work to help combat damage in the body that occurs with cancer treatments, such as chemotherapy. This form of biological therapy stimulates bone marrow stem cells to divide and develop into blood cells. By increasing blood cell production, patients may be able to handle higher doses of chemotherapy. Biological therapy may be the sole means of treating a patient’s cancer, or may be used in combination with other treatments.
The body’s immune system is a complex network of organs and substances that help protect the body from infections and diseases. The system includes the spleen, tonsils, bone marrow and lymph nodes.
When antigens or other foreign substances enter the body, two important white blood cells, phagocytes and lymphocytes, help the immune system begin to work.
Phagocytes engulf and digest microscopic organisms and particles. This process is known as phagocytosis. Types of phagocytes include:
- Monocytes. Circulate in the blood and ingest foreign substances.
- Macrophages. Located in tissues throughout the body. Macrophages recognize and engulf foreign substances, breaking them down before distributing them to T cells for destruction.
Lymphocytes are the most important of the immune system cells. Examples include:
- B cells. Mature into plasma cells that secrete antibodies, proteins that recognize and attach to antigens in the body. Each type of B cell makes a single antibody that recognizes a single specific antigen.
- T cells. Produce proteins called cytokines that facilitate communication between immune system cells. Examples of cytokines include:
- Colony-stimulating factors
- NK cells. Also known as “natural killer cells,” these produce cytokines and proteins that bind to and kill tumor cells.
When the immune system is functioning properly, it recognizes cells associated with disease as foreign and begins to attack them. However, cancer begins with normal cells and the immune system does not always recognize them as foreign. For this reason, it does not work to attack or destroy cancer cells.
Some forms of biological therapy help the immune system recognize cancer as a foreign invader. This therapy works to provide cancer-fighting cells with extra power to attack the disease. This is accomplished using biological therapy drugs, also known as biological response modifiers (BRMs). These drugs are antibodies, cytokines and other immune system substances that can be produced in a laboratory. They change the interaction between the body’s immune defenses and cancer cells to enhance, direct or restore the body’s ability to fight the disease.
Biological therapies are administered in various ways depending on the type of treatment. Oral drugs and some injection treatments may be taken at home, while intravenous administration may require visits to a hospital or clinic. Treatment doses and schedules vary and can range from daily to once every few months.
Types and differences of biological therapy
Biological therapy varies depending on its purpose for the patient. There are a number of different types of biological response modifiers (BRMs) used in biological therapy, including interferons, interleukins, colony-stimulating factors as well as others. Each BRM works differently with the body to fight the cancer or improve the health of a patient undergoing cancer treatment.
Some therapies try to help the immune system to recognize cancer cells as foreign invaders, and to attack them. Other forms act directly on the cancer cells by slowing their growth and development. There are also forms of biological therapy that stimulate blood cell production impaired by cancer or the treatment of cancer.
The BRMs used in biological therapy include:
- Interferons (IFNs). Drugs that mimic a type of cytokine (signal that activates certain immune system cells) made by the body. These medications boost interferon levels to slow the growth of cancer cells and stimulate the immune system to fight cancer cells. They also help promote the transition of cancer cells into cells of normal growth. Some interferons may boost the immune system’s anticancer function by stimulating NK cells, T cells and macrophages. The U.S. Food and Drug Administration (FDA) has approved the use of some interferons for the treatment of certain cancers, including hairy cell leukemia, melanoma and Kaposi’s sarcoma.
- Interleukins (ILs). Another drug group that mimics a cytokine made by the body. A type called interleukin-2 helps boost production of white blood cells. This gives the immune system more power in attacking cancer cells. The FDA has approved interleukin-2 (IL-2) to treat metastatic kidney cancer and melanoma.
- Monoclonal antibodies (MOABs). An artificial antibody (protein that fights off infections) that can be targeted against specific areas of cancer cells. They are injected into the body and attach to the area for which they were made, most often on the surface of certain cancer cells. When this occurs, it helps the body recognize the cancer cells as foreign, triggering the immune system to detect and attack the cells. In addition, MOABs can act directly against cancer cells and interfere with their growth and development. Some MOABs also may be used to help diagnose certain cancers. The FDA has approved several MOABs including Rituxan for non-Hodgkin’s lymphoma and Herceptin for certain metastatic breast cancers. Other MOABs are being studied in clinical trials for the treatment of a variety of cancers.
- Colony-stimulating factors (CSFs). Sometimes called hematopoietic growth factors, these drugs stimulate bone marrow stem cells to divide and develop into white blood cells, red blood cells and platelets. This is important, because bone marrow stem cells are often damaged by treatments such as radiation therapy and chemotherapy. Using CSFs along with chemotherapy can help patients receive higher doses of chemotherapy drugs without increasing the need for blood transfusions. There are numerous FDA-approved CSFs that are used in patients undergoing cancer treatment. In addition, CSFs are being studied in clinical trials for the treatment of many cancers.
- Nonspecific immunomodulating agents. Substances that stimulate and indirectly augment the immune system. These agents act directly on immune system cells and cause secondary responses such as increased cytokine and immunoglobulin production. Bacillus Calmette-Guerin (BCG) and levamisole are two agents that are used in cancer treatment. BCG is being used to treat bladder cancer while levamisole may be used for colon cancer following surgery.
- Antiangiogenesis is a new biological therapy that shows promise in fighting cancer. This strategy prevents tumors from generating new, small blood vessels necessary for the tumor to sustain itself. Several chemicals and antibodies have shown the ability to block angiogenesis, making it possible to shrink the tumor. Researchers are combining antiangiogenesis drugs with chemotherapy drugs, radiation therapy and other forms of treatment in clinical studies.
- Epithelial growth factor receptor (EGFR) inhibitors. EGFR has been associated with aggressive cancer cell growth in tumors. EGFR inhibitors are drugs that may help prevent the development and progression of cancer in certain tumors.
- Gene therapy. This treatment is based on altering a cell’s genetic material to fight or prevent disease. It is an experimental method that involves introducing genetic material, such as DNA, into an individual’s cells to fight cancer. Some approaches of gene therapy target the destruction of cancer cells to prevent their growth. Other forms of gene therapy focus on increasing the ability of healthy cells to fight cancer. Gene therapy is currently available only in clinical trials.
There are several therapy techniques being studied with gene therapy. Researchers are evaluating the replacement of missing or altered genes with healthy genes. In another approach, researchers are injecting cancer cells with genes that can be used to destroy the cells or genes that can make the cells more sensitive to chemotherapy and radiation therapy. Scientists continue to study additional uses of gene therapy in cancer treatment.
- Cancer vaccines. This form of biological therapy is currently under study for a number of cancers. Vaccines are effective because they expose a person’s immune cells to a weakened form of the disease. This exposure to the antigens present on the surface of the foreign invader causes the immune system to increase the production of antibodies and T cells to fight the infection.
Cancer vaccines are being studied to treat existing cancers or to prevent healthy individuals from developing cancer. Early cancer vaccine trials are being used with many types of cancer including men’s and women’s reproductive cancers. In 2006, the FDA approved the first vaccine against human papillomavirus (HPV), the virus responsible for most cases of cervical cancer. Vaccines have also shown promise for cancers of the breast, lung, kidney and liver
Conditions treated with biological therapy
Biological therapy is still in early stages of development but has produced some exciting results. Some biological therapies are a standard part of treatment for certain types of cancer, while others are only offered in clinical trials.
Biological therapy is often used in conjunction with other forms of cancer treatment, such as chemotherapy. A patient’s medical oncologist can best determine if biological therapy is a viable treatment option. Biological therapy has been applied to treatment of a number of cancers, including:
- Kidney cancer
- Colon cancer
- Cancers of the blood (leukemias)
- Kaposi’s sarcoma
- Breast cancer
- Female reproductive cancers (e.g., ovarian, cervical)
- Prostate cancer
- Lung cancer
Biological therapy has shown to be successful in the treatment of a number of cancers. The therapy may be used to restrict the process that leads to cancer development and improve the immune system’s response to fight cancer. It also is beneficial in repairing or replacing healthy cells that have been damaged during cancer treatments.
Potential side effects of biological therapy
While biological therapy has shown great benefits in treating some cancers, it can cause side effects. These may include:
- Rashes or swelling at an injection site
- Flu-like symptoms, including fever, chills, nausea, vomiting, loss of appetite, fatigue, bone pain and muscle aches
- Low blood pressure
- Allergic reactions
The side effects of biological therapy can vary depending on the type of treatment, specific cancer and health of the patient. Since biological therapies are relatively new, the long-term effects on patients are not fully known.
Questions for your doctor on biological therapy
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about biological therapy:
- Am I a candidate for this type of treatment?
- Is it approved for my type of cancer or will I need to be enrolled in a clinical trial?
- What drugs will be used in my biological therapy?
- How would I receive the treatment?
- Can I take the drugs at home?
- What are the risks associated with the treatment?
- How long would I receive the treatment?
- How effective is biological therapy for my type of cancer?
- What are the side effects of this type of treatment?
- How will I know if the biological therapy is working?
- What is my prognosis with and without biological therapy?
- Is this type of biological therapy considered experimental for my cancer?