Biological Therapies

Biological therapy is also called immunotherapy or biological response modifiers.  It is a relatively new type of cancer treatment.  Biological therapies use 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 treatment.

The immune system is a complicated network of cells and organs.  The bone marrow, thymus gland, spleen and lymph nodes work together to defend the body against attacks by “foreign” invaders.  The immune system is the body’s main defense again infection and disease. 

The immune system works against diseases, including cancer, in several ways.  The immune system may recognize the difference between healthy cells and cancer cells in the body and work to get rid of the cancer cells.  However, the immune system cannot always recognize cancer cells as “foreign”.  Also, cancer may develop when the immune system breaks down or does not function adequately. 

Biological therapies work on the immune system in various ways by repairing, stimulating or enhancing the immune system’s responses.

Biological Response Modifiers  (BRM)

Some antibodies, cytokines (proteins secreted by cells of the immune system) and other immune system substances can be produced in the laboratory for use in cancer treatment.  They alter the interaction between the body’s immune defenses and cancer cells to boost, direct, or restore the body’s ability to fight disease.  Interferons, interleukins, colony stimulating factors, monoclonal antibodies, vaccines, gene therapy, and non specific immunomodulating agents are examples of biologic response modifiers.

Interferon

Interferons are types of cytokines that occur naturally in the body.  They were the first cytokines produced in the laboratory for use as BRMs.  There are three major types of interferons—interferon alpha, interferon beta, and interferon gamma.  Interferon alpha is the type most widely used in cancer treatment.

Researchers have found that interferons can improve the way a cancer patient’s immune system acts against cancer cells.  In addition, interferons may act directly on cancer cells by slowing their growth or promoting their development into cells with more normal behavior. 

The US Food and Drug Administration has approved the use of interferon alpha for the treatment of certain types of cancer, including hairy cell leukemia, melanoma, and Kaposi’s sarcoma. 

Interleukin

Like interferons, interleukins are cytokines that occur naturally in the body and can be made in the laboratory.  Many interleukins have been identified.  Iinterleukin-2 has been the most widely studied in cancer treatment.  Interleukin-2 stimulates the growth and activity of many immune cells, such as lymphocytes, that can destroy cancer cells.  Interleukin-2 has been approved for the treatment of metastatic kidney cancer and metastatic melanoma.

Colony-stimulating factors (SF)

Colony-stimulating factors sometimes called hematopoietic growth factors, usually do not directly affect tumor cells; rather, they encourage bone marrow stem cells to divide and develop into white blood cells, platelets, and red blood cells.  Bone marrow is critical to the body’s immune system because it is the source of all blood cells.

Colony-stimulating factor’s stimulation of the immune system may benefit patients undergoing cancer treatment.  Because anticancer drugs can damage the body’s ability to make white blood cells, red blood cells, and platelets, patients receiving anticancer drugs have an increased risk of developing infections, becoming anemic, and bleeding more easily.  By using CSFs to stimulate blood cell production, doctors can decrease the risk of infection or the need for transfusion with blood products, due to chemotherapy treatment.

Monoclonal antibodies (MOAB)

Monoclonal antibodies are antibodies made in a laboratory.  These antibodies are produced by a single type of cell and are specific for a particular antigen.  Researchers are examining ways to create MOABs specific to the antigens found on the surface of various cancer cells.

MOABs may be used in cancer treatment in a number of ways:

• MOABs that react with specific types of cancer may enhance a patient’s immune response to the cancer
• MOABs can be programmed to act against cell growth factors, thus interfering with the growth of cancer cells
• MOABs may be programmed to act against cell growth factors, thus interfering with the growth of cancer cells.
• MOABs may be linked to anticancer drugs, radioisotopes, other biological response modifiers or other toxins.  When the antibodies latch onto cancer cells, they deliver these poisons directly to the tumor, helping to destroy it.

Rituxan and Herceptin are examples of MOABs that have been approved by the Federal Drug Administration.  Rituxan is used for the treatment of non-Hodgkins lymphoma.  Herceptin is used to treat metastatic breast cancer in patients with tumors that produce excess amounts of the protein called HER-2.

Cancer Vaccines

Cancer vaccines are another form of biological therapy currently under study.  Vaccines for infectious disease, such as measles, mumps, and tetanus, are injected into a person before the disease develops.  These vaccines are effective because they expose the body’s immune cells to weakened forms of antigens that are present on the surface of the infectious agent.  This exposure causes the immune system to increase production of plasma cells that make antibodies specific to the infectious agent.  The immune system also increases production of T cells that recognize the infectious agent.  These activated immune cells remember the exposure, so that the next time the agent enters the body, the immune system is already prepared to respond and stop the infection.

Researchers are developing vaccines that may encourage the patient’s immune system to recognize cancer cells.  Cancer Vaccines are designed to treat existing cancers (therapeutic) or to prevent the development of cancer.  Therapeutic vaccines are injected in a person after the cancer is diagnosed.  These vaccines may stop the growth of existing tumors, prevent cancer from recurring or eliminate cancer cells not killed by prior treatments.  Cancer vaccines given when the tumor is small may be able to eradicate the cancer.

Gene Therapy

Gene therapy is an experimental treatment that involves introducing genetic material into a person’s cells to fight disease.  Researchers are studying gene therapy methods that can improve a patient’s ability to recognize and attack cancer cells.  In another approach, scientists inject cancer cells with genes that cause the cancer cells to produce cytokines and stimulate the immune system.  A number of clinical trials are currently studying gene therapy and its possible application to the treatment of cancer.

Non Specific Immunomodulating agents

Nonspecific immunomodulating agents are substances that stimulate or indirectly augment the immune system.  Often these agents target key immune system cells and cause secondary responses such as increased production of cytokines and immunoglobulins.  Examples of nonspecific immunomodulating agents are BCG or bacillus Calmette-Guerin used to treat bladder cancer and levamisole.  Levamisole is sometimes used along with Fluorouracil (5 FU) in treating some stages of colon cancer.

Side Effects of Biological therapies

Like any form of treatment biological therapies can cause a number of side effects, which can vary widely from agent to agent and patient to patient.  Rashes or swelling may develop at the site where the BRMs are injected.  Several BRMs, including interferons and interleukins, may cause flu like symptoms including fever, chills, nausea, vomiting, and appetite loss.  Fatigue is another common side effect of some BRMs.  Blood pressure may also be affected.  The side effects of interleukin 2 can often be severe, depending on the dosage given.  Patients need to be closely monitored during treatment with high doses of interleukin 2.  Side effects of colony stimulating factors may include bone pain, fatigue, fever, and appetite loss.  The side effects of monoclonal antibodies vary, and serious allergic reactions may occur.  Cancer vaccines can cause muscle aches and fever.