Immunotherapy (also called biologic therapy or biotherapy) is a type of cancer treatment that uses the body's immune system to fight cancer. Although it is not certain how immunotherapy treats cancer, some possible ways include:

• Stopping or slowing the growth of cancer cells
  
  
• Stopping the cancer from spreading to other parts of the body
  
  
• Helping the immune system be more effective in eliminating cancer cells

There are several types of immunotherapy, including monoclonal antibodies, non-specific immunotherapies, and cancer vaccines.

Monoclonal antibodies

Monoclonal antibodies are made in a laboratory and act like the antibodies the body naturally produces as part of the immune system's response to fight diseases such as cancer.

Monoclonal antibodies are injected into a vein (intravenously, IV), and work by targeting proteins on the surface of cancer cells or cells that support the growth of cancer cells, called antigens. When monoclonal antibodies attach to a cancer cell, they can:

Allow the immune system to destroy the cancer cell. The immune system doesn't always recognize cancer cells. A monoclonal antibody can be directed to attach to specific parts of a cancer cell. In this way, the antibody marks or tags the cancer cell and makes it easier for the immune system to find.

Prevent cancer cells from growing rapidly. Chemicals in the body called growth factors attach to receptors on the surface of cells and signal the cells to grow. Some cancer cells make extra copies of the growth factor receptor, which makes the cancer cells grow faster than normal cells. Monoclonal antibodies can block these receptors and prevent the growth signal from getting through.

Deliver radiation directly to cancer cells. Some monoclonal antibodies carry tiny radioactive particles directly to cancer cells, without damaging healthy cells. Monoclonal antibodies that carry these radioactive particles deliver a low level of radiation over a longer time, which researchers believe is as effective as high-dose external beam radiation (radiation delivered from a machine outside the body). Ibritumomab (Zevalin) and tositumomab (Bexxar), treatments for non-Hodgkin lymphoma, are examples.

Diagnose cancer. Monoclonal antibodies carrying radioactive particles with the use of special cameras may also help diagnose certain cancers, such as colorectal, ovarian, and prostate cancers. Monoclonal antibodies are also used by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease) when tissue is removed from a patient to determine the type of cancer a patient may have.

Carry powerful drugs directly to cancer cells. Some monoclonal antibodies carry other cancer drugs directly to cancer cells. Once the monoclonal antibody attaches to the cancer cell, the cancer treatment it is carrying enters the cancer cell, causing the cell to die without damaging other healthy cells. Gemtuzumab (Mylotarg), a treatment for acute myeloid leukemia (AML), is one example.

Monoclonal antibodies are also classified as a type of targeted treatment (a treatment that targets faulty genes or proteins that contribute to cancer growth and development). Read more about targeted treatments. Here are some other monoclonal antibodies approved by the U.S. Food and Drug Administration (FDA) to treat cancer:

• Bevacizumab (Avastin)
  
  
• Alemtuzumab (Campath-1H)
  
  
• Cetuximab (Erbitux)
  
  
• Trastuzumab (Herceptin)
  
  
• Rituximab (Rituxan)
  
  
• Panitumumab (Vectibix)

Clinical trials of monoclonal antibodies are ongoing for several types of cancers. Learn more about clinical trials.

Side effects of monoclonal antibody treatment are usually mild and are often similar to an allergic-type reaction. Possible side effects include rashes, low blood pressure, and flu-like symptoms, such as fever, chills, headache, weakness, extreme tiredness, loss of appetite, upset stomach, or vomiting.

Non-specific immunotherapies

Non-specific immunotherapies also help the immune system fight cancer. Most non-specific immunotherapies are given after or at the same time as other cancer treatments, such as chemotherapy or radiation therapy. Some non-specific immunotherapies are given alone as treatments.

Here are three common non-specific immunotherapies:

Interferons. Interferons help the immune system fight cancer and may also slow the growth of cancer cells. An interferon made in a laboratory, called interferon alpha (Roferon-A [2a], Intron A [2b], Alferon N), is the most frequently used interferon in cancer treatment. Interferon alpha is used to treat non-Hodgkin lymphoma, hairy cell leukemia, kidney cancer, melanoma, chronic myeloid leukemia (CML), and Kaposi's sarcoma. Side effects of interferon treatment may include flu-like symptoms, an increased risk of infection, rashes, and thinning hair.

Interleukins. Interleukins help the immune system produce cells to help fight cancer. An interleukin made in a laboratory, called interleukin-2, IL-2, or aldesleukin (Proleukin), is used to treat kidney cancer and skin cancer, including melanoma. Common side effects of IL-2 treatment are weight gain and low blood pressure, which can be treated with other medications. Some people may also experience flu-like symptoms.

Cancer vaccines

A vaccine helps the body fight disease. There are two types of cancer vaccines: prevention vaccines and treatment vaccines.

A prevention vaccine is given to a person with no symptoms of cancer to prevent the development of a specific type of cancer (or other disease). For example, Gardasil is a vaccine that prevents a woman from being infected with the human papillomavirus (HPV), a virus known to cause cervical cancer. This is the first FDA-approved vaccine for cancer. Cervarix is another vaccine that is approved to prevent cervical cancer in girls and women between ages 10 and 25. Learn more about HPV vaccination for cervical cancer and the role of HPV in other cancers. Another vaccine prevents infection with the hepatitis B virus, which may cause liver cancer.

A treatment vaccine helps the body's immune system fight cancer. A treatment vaccine may prevent cancer from coming back, destroy any remaining cancer cells after other types of treatment, or stop cancer cell growth. A cancer vaccine is designed to be specific, which means it is supposed to target the cancerous cells and not the healthy cells. At this time, sipuleucel-T (Provenge) for metastatic prostate cancer is the only treatment vaccine approved in the United States. Additional cancer treatment vaccines are still in development and only available through a clinical trial. Read more about cancer vaccines.

Questions to ask the doctor

Ask your doctor whether immunotherapy may be a part of your treatment plan. If so, consider asking the following questions:

• Why do you recommend immunotherapy for me?
  
  
• What are the goals of this treatment?
  
  
• Will immunotherapy be my only treatment? If not, what other treatments will be a part of my treatment plan?
  
  
• How will I receive immunotherapy treatment and how often?
  
  
• What are the possible side effects of immunotherapy, both in the short term and long term?
  
  
• How will this treatment affect my daily life? Will I be able to work, exercise, and perform my usual activities?
  
  
• What clinical trials of immunotherapies are open to me?

More Information

Understanding Cancer Vaccines

Types of Treatment

Managing Side Effects

Additional Resources

American Cancer Society: Immunotherapy

National Cancer Institute: Biological Therapies for Cancer: Questions and Answers

Last Updated: August 16, 2010