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The U.S. Food and Drug Administration (FDA) has announced the approval of the
drug Herceptin (generic name, trastuzumab) for use in early stage breast cancer patients
after treatment with surgery - either mastectomy or
lumpectomy. The approval comes after two large government-funded
studies found that Herceptin reduce relapses after treatment. Herceptin is only approved for women with a certain
type of breast cancer called HER 2-positive breast cancer.
HER2 (human epidermal growth factor receptor 2) is a protein found on the surface of cells that, when
functioning normally, has been found to be a key component in regulating cell growth. However, when the HER2 protein
is altered, extra HER2 protein receptors may be produced. This over-expression of HER2 causes increased cell growth and
reproduction, often resulting in more aggressive breast cancer cells. Women with HER2 over-expression may
not be as responsive to standard breast cancer treatments, including certain regimens of
chemotherapy.
Herceptin works by targeting breast cancer cells that have too many copies of the HER2 protein. After it has identified
which cells over-express the HER2 protein, Herceptin attaches itself to the HER2 protein receptors on the surface
of these cells. By binding to the cells, Herceptin slows the growth and spread of tumors that have an overabundance
of HER2. Many experts believe that Herceptin represents the future direction of breast cancer drugs in that it targets
a particular protein of the cancer cell and prevents it from carrying out its action, similar to the leukemia drug, Gleevec.
In 1998, the FDA approved Herceptin for the treatment of metastatic
breast cancer (cancer that has spread to other body organs). The
FDA's recent approval expands its use to women with cancer only in the breast or lymph nodes which has been removed
with surgery. The approval comes after two large government-funded studies found that Herceptin can significantly
reduce the recurrence of breast cancer, when given in combination with chemotherapy.
The studies involved over 3,300 women with HER2 positive breast cancers. Patients were randomly selected to receive
either standard chemotherapy (with the drugs doxorubicin and cyclophosphamide) followed by treatment with the drug
paclitaxel, or the same form of standard chemotherapy followed by treatment with the drugs paclitaxel and
Herceptin. Most patients who enrolled in the studies had breast cancers that had spread to their nearby lymph nodes.
Women who were treated with chemotherapy and Herceptin were significantly less likely to experience a recurrence of
their disease. "This is a major advance for many thousands of women with breast cancer," said U.S. National
Cancer Institute Director Andrew C. von Eschenbach, MD, in an NCI news release. "These results are one more example that
we are at a major turning point in the use of targeted therapies to eliminate suffering and death from cancer."
Other cancer experts agreed that the studies are a significant advance in targeted breast cancer treatment. "These
are truly life-saving results in a major disease," said JoAnne Zujewski, MD of the National Cancer Institute, in an
NCI news release. Edward Romond, MD, study chair for the National Adjuvant Breast and Bowel Project and professor of
oncology at the University of Kentucky, in Lexington, Kentucky, noted, "For women with this type of aggressive
breast cancer, the addition of [Herceptin] to chemotherapy appears to virtually reverse prognosis from unfavorable to good."
According to the FDA, the most serious side effect of Herceptin is heart failure (weakening of the heart muscle) that
requires medical treatment. Due to the risk of heart disease, only certain patients should receive the drug, including:
- Only patients whose tumors are HER2 Positive
- Patients who do not have heart failure or weak heart muscle.
Women who receive Herceptin must be screened for heart function before beginning and during treatment. According to the
FDA, less common but serious side effects include infusion reactions (chills, fever, shortness of breath) that rarely are
accompanied by lung problems, low white blood counts, and low red blood cell counts.
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