Herceptin - Treating Breast Cancer: Breast Cancer

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Herceptin

One of the tumor characteristics used to guide therapy is the presence of cancer cells that produce high levels of a protein called HER2/neu. This protein exists in small amounts on the surface of healthy breast cells and on some breast cancer cells. However, about 20%-25% of breast cancer cells have too much HER2. Cancer cells that overproduce HER2 (the term "overexpress" is used in pathology reports) tend to spread more aggressively than those with normal amounts of the protein.

Monoclonal antibodies are drugs designed to target specific cells. The monoclonal antibody trastuzumab (Herceptin) attacks the cancer cells that produce HER2. Herceptin can block HER2 from stimulating cell growth and appears to encourage the immune system to attack cancers more effectively.

Herceptin is sometimes added to chemotherapy, forming a combination that is more effective than chemotherapy alone for women with breast cancer that has metastasized. Herceptin is given intravenously, generally every week, but studies show that it can be given every three weeks, with the same total dose. Although serious side effects are rare, 30%-40% of women have reactions such as fever, chills, shortness of breath, or blood pressure changes the first time they receive the drug.

Now that Herceptin is being used more frequently, doctors are noticing a higher than expected rate of heart muscle damage. This seems to be especially true for women who have also received chemotherapy programs that include cyclophosphamide and doxorubicin.

Created by the Faculty of the Harvard Medical School

Copyright Harvard Medical School, Harvard University, 2007

Last updated:	April 23, 2007