Medication for Women with Advanced Breast Cancer
En Español (Spanish Version)
All women with advanced
breast cancer
face a difficult and uncertain future. Most of them endure long courses of treatment that leave them looking to alternative or experimental therapies for a cure. A drug called
trastuzumab
(Herceptin)
attacks a particularly aggressive form of breast cancer in a novel way.
One more aggressive form of breast cancer is characterized by an overabundance of a protein known as human epithelial growth factor receptor-2 (HER-2). This protein stimulates the growth of breast tumors. Trastuzumab is a monoclonal antibody, which blocks the HER-2 receptor. This inhibits the growth of malignant cancer cells by eventually causing their death.
Since 1986, scientists have known that women whose breast cancers produce too much HER-2 have cancers that are more aggressive and are more likely to metastasize, or spread. Trastuzumab can enhance the effectiveness of standard
chemotherapy
treatments by targeting the HER-2 receptor and inhibiting its activity.
"We have a new agent that is effective," said Dr. Dennis Slamon, vice-chair of research at the University of California at Los Angeles, and one of the primary researchers behind Herceptin. Two of his research trials provided information that helped Herceptin get approved less than five months after submission to FDA.
Slamon's first study showed that nearly half of all women with Her-2/neu positive tumors receiving Herceptin and chemotherapy had slower cancer growth and responded better to treatment than women who didn't receive the Herceptin. Perhaps most encouraging was the news that the women who received Herceptin also had better one-year survival rates.
"The addition of Herceptin made a significant increase in all of the parameters we looked at," Dr. Slamon commented when the results of his trials were first made public. After one year of treatment, cancer growth was halted in 28% of women treated with Herceptin plus chemotherapy, compared with 14% receiving just chemotherapy.
Another study showed that the use of Herceptin alone could benefit some seriously ill women whose previous chemotherapy treatments had failed. In these patients, who usually did not respond to any new treatments, about 14% responded to the drug for an average of about nine months.
Studies published in 2007 showed that Herceptin significantly decreased tumor recurrence in women with Her-2 receptors, whether or not they had “positive” metastatic lymph nodes at the time of treatment. These findings potentially extend the usefulness of Herceptin to all women with Her-2 receptors in their tumors, regardless of whether or not their tumors are advanced. It is important to note that Herceptin does not improve outcomes for women with cancers not expressing Her-2 receptors.
While trastuzumab may be able to slow the growth of cancer cells, there are serious side effects associated with this drug.
Cardiomyopathy
is a potentially life-threatening heart muscle weakness that can lead to
congestive heart failure
. This side effect is particularly common in women receiving chemotherapy with anthracyclines and cyclophosphamide. For this reason, the FDA recommends that every woman considering trastuzumab have a thorough cardiac assessment before taking the drug and during treatment.
Other serious side effects include:
- Damage to the lungs
- Life-threatening allergic reaction
- Anemia
More common side effects include:
It is important to remember that trastuzumab, since its approval in 1998 by FDA, has been used only in women with breast cancer that overproduces HER-2 and is so advanced that it has spread to other parts of the body. But,
researchers continue to investigate other ways to use trastuzumab, including which combination of medicines are the most effective and which other forms of cancer may be treated with trastuzumab.
National Cancer Institute
Canadian Breast Cancer Foundation
Herceptin prescribing information. Genentech website. Available at:
http://www.gene.com/
. Accessed November 2006.
Hortobagyi GN. Trastuzumab in the treatment of breast cancer.
N Engl J Med.
2005;353:1734-1736.
Romond EH, Perez EA, Bryant J, et al. Trastuzumab plus adjuvant chemotherapy for operable HER2-positive breast cancer.
N Engl J Med.
2005;353:1673-1684.
Slamon DJ, Leyland-Jones B, Shak S, et al. Concurrent administration of anti-HER2 monoclonal antibody and first-line chemotherapy for HER2-overexpressing metastatic breast cancer: A phase III, multinational, randomized, controlled trial.
N Engl J Med.
2001;344:783-792.
Last Reviewed December 2010