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Biological Therapy for Breast Cancer

Biological therapy for breast cancer is designed to stimulate your natural immune system to fight cancer cells more effectively.

Sending in Reinforcements

Learn how biological therapies reinforce the body’s power to protect and heal itself in Your Guide to Cancer Care.

Currently, one of the most widely used biological therapies for breast cancer is Herceptin®, known generically as trastuzumab. This treatment is part of a class of immunotherapies called monoclonal antibodies, which are targeted at specific antigens, or proteins, on the surface of cancer cells. When monoclonal antibodies are injected, they attach to the antigens and destroy the cancer cells or limit their ability to reproduce.

Herceptin, in particular, targets a protein in cancer cells called Her2/neu. Also known as human epidermal growth factor 2, Her2/neu is a protein necessary for normal cell growth. However, some breast cancers produce, or express, too much of this protein. By blocking HER2/neu, Herceptin can slow or stop the growth of the cancer cells.

Antibodies and Antigens

Antibodies are proteins produced by the immune system when it recognizes foreign substances, such as a bacteria, toxin, or virus. These substances are called antigens.

You may receive Herceptin if diagnostic tests performed on a sample of tumor cells indicate that the breast cancer exhibits high levels of HER2/neu. These tests are sometimes called tumor-marker tests or immunohistochemistry. About 30% of people with breast cancer test positive for overproduction of this protein, which may signal a more aggressive form of the disease. Herceptin is generally prescribed to people with metastatic breast cancer. It’s injected into a vein and may be given by itself or along with chemotherapy.

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