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Biological Therapy for Breast Cancer

Biological therapy for breast cancer takes advantage of the body's own immune or hormonal system to act on cancer cells - while leaving healthy cells relatively intact. This approach is designed to minimize the side effects associated with traditional treatments like chemotherapy.

One strategy is to use antibodies to attack cancer cells or block their activities. An antibody is a protein that can attach to specific proteins in the body, called antigens. Antibodies can be natural, made by one's own immune system, or made artificially. One example of a manufactured antibody is Herceptin.

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Herceptin is believed to act in three ways to stop cancer cells from growing quickly and out of control:

  • It sticks to special receptors on the cancer cells, stopping them from growing.
  • It signals the body's own natural killer cells to attack the cancer cells.
  • It can work with chemotherapy medications, stopping cancer cells damaged by chemo from repairing themselves.

But Herceptin can work only if the woman carries the HER-2 gene in those tumor cells. About 30% of breast cancer patients carry this gene. (They are considered HER2-positive). It currently is the first-line treatment of HER2-positive metastatic breast cancer used in combination with one of the drugs known as taxanes (Taxotere, Taxol, and Abraxane).

Another form of biological therapy is the use of drugs composed of small molecules that interrupt the hormonal or chemical pathways that cancer cells need to grow. Tykerb is an example of a small molecule that is used in combination with chemotherapy to treat some advanced cases of breast cancer.

One disadvantage of antibody treatment is that it is generally only available by injection. Small molecule treatment can be taken in pill form.

Perjeta is a drug used to treat HER2-positive metastatic breast cancer used in combination with Herceptin and TaxotereAnother medication, Kadcyla, is for use in patients with HER2-positive, late-stage breast cancer who were previously treated with Herceptin and chemotherapy with one of the taxane drugs mentioned above. These medications may have been used in combination or separately. 

In HER2-negative breast cancer, Afinitor can be taken with the drug exemestane in postmenopausal women who have already tried certain other treatments. Afinitor is for advanced cancer that's also hormone receptor-positive.  

Other types of antibodies and small molecules that are being researched to fight breast cancer include:

  • Angiogenesis inhibitors. These antibodies prevent the growth of new blood vessels, cutting off the supply of oxygen and nutrients to cancer cells. Avastin, which had been used to treat breast cancer, is no longer approved by the FDA because the risks outweigh the benefits.
  • Signal transduction inhibitors. These antibodies block signals inside the cancer cell that helps the cells divide, stopping the cancer from growing.


Side Effects of Biological Therapy

Side effects of biological therapy can include allergic reactions, difficulty breathing, swelling, nausea, fever or chills, and dizziness or weakness. Side effects can differ from one medicine to another. Talk to your doctor about the possible side effects to watch for.

WebMD Medical Reference

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