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Herceptin is a drug that is used to treat metastatic breast cancer (cancer that has spread beyond the breast and axillary lymph nodes to bone, lungs, liver or other areas). Herceptin is a monoclonal antibody. Antibodies are proteins that your body makes in response to foreign substances such as bacteria and viruses. When you receive a flu shot, for example, your body makes antibodies to viral proteins in the vaccine so that you will quickly recognize the influenza viruses and destroy them before you become ill. Your body also makes antibodies to tumor cells, but these antibodies may not be enough to attack a growing cancer. About 25-30% of all breast cancers make large amounts of a protein called HER-2. Other types of cancer cells may also make increased HER-2. Normal cells do not usually produce this protein. Herceptin interacts with HER-2 on the surface of cancer cells and helps the immune system to recognize and eliminate the cancer cells. Who might benefit from treatment with Herceptin? Herceptin works only on cancers that express large amounts of HER-2. Before recommending this treatment, your physician must request that your tumor be tested for HER-2 expression. If your initial surgery was performed at St. Joseph Mercy Hospital, we can request that our Pathology Department obtain a piece of the tumor stored at that time. If your surgery was performed at another hospital, we will ask you to sign a release so that we can attempt to obtain the tumor specimen for testing. If the tumor cannot be obtained or if there is insufficient tumor and if you have disease that can easily be biopsied, it may be possible to obtain a new piece of tumor for testing. Herceptin does not work on tumors that do not express the HER-2 protein or that express it only weakly. Herceptin will not be administered to patients with negative or weakly positive tests or to patients whose tumors cannot be tested. Herceptin is currently approved only for patients with metastatic breast cancer. Herceptin is not approved as adjuvant therapy for women with early stage breast cancer, although clinical trials are currently looking at the role of Herceptin in early breast cancers and other types of cancer. How is Herceptin administered? Herceptin is administered as an intravenous infusion once each week. The first week consists of a loading dose given over approximately 90 minutes. Subsequent doses are given over 30 minutes. Herceptin is given weekly as long as there is evidence that the cancer is responding. How well does Herceptin work? Herceptin works best when given in combination with chemotherapy. In clinical trials patients who received chemotherapy and Herceptin experienced a significantly longer time to disease progression, a higher overall response rate, a longer median duration of response, and a higher one-year survival rate. The best results were obtained when Herceptin was given in combination with Taxol. Although studies looked at Herceptin in combination with Adriamycin and Cytoxan, this program has been discontinued due to a high incidence of heart problems. Women treated with Taxol alone developed progressive cancer after an average of 2.5 months, while those treated with Taxol and Herceptin developed progressive disease after 6.7 months. 15% of women treated with Taxol alone had good responses compared to 38% of women treated with Taxol and Herceptin. After one year 61% of women treated only with Taxol were alive compared to 73% of women treated with the combination of Taxol and Herceptin. These studies were conducted on women who had received no previous chemotherapy for metastatic disease. In women who have already received one or more chemotherapy regimens for metastatic breast cancer Herceptin will probably not be as effective. The results with Herceptin alone were not as good. Therapy with Herceptin as a single drug is recommended only for women who have already failed one or more previous chemotherapy programs for their metastatic disease or for those women who have significant side effects from previous chemotherapy programs (e.g., nerve damage from Taxol). Early studies suggest that Herceptin may be used in combination with other drugs including Cis-Platin, Carboplatin and Navelbine. These drugs however may also be associated with neuropathies. What are the side effects of Herceptin? Herceptin has been associated with a variety of side effects. These are described below: CARDIAC TOXICITY Herceptin administration can result in severe heart damage leading to congestive heart failure, stroke and death. The risk of heart damage is highest in patients who receive Adriamycin and Cytoxan at the same time, but may also occur in patients receiving Herceptin alone or in combination with other drugs. At this point we are not certain how Herceptin will affect patients who have previously received Adriamycin and Cytoxan, irradiation to the chest, or high-dose chemotherapy with bone marrow or stem cell rescue. All patients receiving Herceptin will have a baseline heart evaluation including an echocardiogram or a MUGA test to determine heart function. This test will be repeated periodically. However, heart problems can occur at any time, cannot be accurately predicted by monitoring tests, and can be very severe. In studies done to date 7-11% of patients developed heart problems, and 4-5% of these were severe. INFUSION-ASSOCIATED SYMPTOMS During the first infusion with Herceptin about 40% of patients developed chills and or fever. These symptoms were mild to moderate in severity and easily treated. Other signs and symptoms included nausea, vomiting, pain (sometimes at tumor sites), headache, dizziness, shortness of breath, low blood pressure, rash, weakness and fatigue. These symptoms did not usually occur with subsequent infusions. DIARRHEA Diarrhea occurred frequently in patients treated with Herceptin alone or in combination with chemotherapy. BONE MARROW SUPPRESSION Anemia and low white blood counts occurred in some patients receiving Herceptin and chemotherapy. Infections were also more common, especially mild upper respiratory infections and catheter infections (e.g., PASport infections). Herceptin is not recommended for women who are pregnant or nursing. While Herceptin has not been shown to interfere with fertility, data are inconclusive. Fertile women on Herceptin are advised to use reliable contraception. Ann
Arbor Hematology Oncology Associates, P.C. |