Biologic Therapy: The Basics

Carolyn Vachani, RN, MSN, AOCN & Lara Bonner Millar, MD
Abramson Cancer Center of the University of Pennsylvania
Last Modified: November 22, 2010

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What is biologic therapy, and how does it work?

Biologic therapies help the immune system to function better by using substances that occur naturally in your body. The therapy may stimulate your body to make more of the substance, or the therapy may be a man-made version of that natural substance itself. Other types of therapies use cells from the patient's body, which are then altered in a laboratory and given back to the patient. Alternative names for biologic therapies include biologic agents, biologics, biological response modifiers (BRMs), or immunotherapy. Biologic therapy differs from chemotherapy because chemotherapy affects cancer cells directly whereas biologic therapy works with the immune system to fight cancer. Biologics used for cancer treatment include Bacillus Calmette-Guérin (BCG) which treats early stage bladder cancer, Interleukin-2 (IL-2) for certain melanomas and kidney cancer, Rituxan (Rituximab) for non-Hodgkin's lymphoma, and Herceptin (Trastuzumab) for breast cancer, among many others.

The body's immune system helps to prevent disease, but it also plays a role in preventing cancer from developing or spreading. The goal of biologic therapy is to enhance this natural defense and its ability to fight cancer. Doctors do not completely understand how these therapies work to fight cancer, but the treatments are thought to stop or slow the growth of cancer cells, to make it easier for the immune system to destroy these cells, and to prevent cancer from spreading to other parts of the body.

Some biologics are used to help deal with the side effects of other treatments. For example, colony stimulating factors (G-CSF or Neupogen) can help the body increase the production of white blood cells after chemotherapy and thereby decrease the risk of neutropenia, and in turn, infection. Epogen is an injectable biologic that stimulates red blood cell production. Just as there are many different ways of stimulating the immune system, there are different types of biologic therapies. Some of the biologic therapies include: interferon, interleukin, colony stimulating factors, monoclonal antibodies, vaccines and gene therapy.

How are biologic therapies given?

This varies depending on the particular type of biologic therapy being used. Therapies may be given by mouth, into a vein (intravenously), or by injection, either under the skin (subcutaneous) or into a muscle (intramuscular). Therapies may also be given directly into a body cavity to treat a specific site. For example, gene therapy being tested in a clinical trial for mesothelioma (a cancer of the linings of the lung) may be injected into the space between the lung and the chest wall. Some of these therapies are approved by the U.S. Food and Drug Administration, but many are still being tested in clinical trials. Depending on the type of cancer and how far it has spread, some patients may only need biologic therapy, while others may receive this in conjunction with other therapies (i.e. chemotherapy, surgery, or radiation therapy).

What are the side effects of biologic therapies?

Although some biologic therapies use substances that occur naturally in the body, side effects can occur as a result of either the greater production or the higher-than-normal doses administered. The most common side effects with biologic therapies are caused by the "revving up" and stimulation of the immune system. They include fever, chills, body aches, nausea/vomiting, loss of appetite, and fatigue. Depending on the doses and how the therapy is administered, patients may experience a decrease in their blood pressure and may develop a rash or swelling at the injection site. Most side effects diminish at 24-48 hours after treatment, and for continuous regimens these side effects will lessen over time. Remember, every patient is different; some may develop all of the side effects, while others may have none or be somewhere in between. Biologic therapies are relatively new, and we are still learning what long-term side effects they may lead to years later. Visit OncoLink Rx to learn more about a specific therapy.

How do I know if biologic therapy is working for me?

This answer varies, depending on the type and extent of cancer being treated. Many patients will have radiology studies (CT scans, MRIs, PET scans) periodically to see if the tumor has responded (either shrunk or stayed the same versus grown). Some types of tumors can be measured in the blood with a "tumor marker." This is a substance that is either produced by the tumor or by the body in response to the tumor, and can be measured by a blood test. If the chemotherapy is working, one would expect the tumor marker to decrease. In some cases, a decrease in a patient's symptoms may signal whether or not the medications are shrinking the tumor. Talk with your doctor or nurse about how your response will be measured.