Vaccines, an emerging type of promising biologic therapy which utilize the immune system to attack cancer cells, are showing potential for the treatment of metastatic breast cancer. (Proceedings from the American Society of Hematology, 42nd annual meeting, 2000).
Breast cancer is a common malignancy occurring in women in the United States with almost 200,000 new cases diagnosed each year. Breast cancer is characterized by the presence of cancer cells in the tissue or ducts of the breast. Metastatic breast cancer refers to cancer that has spread outside the breast to lymph nodes and distant locations in the body, often invading vital organs.
With current standard treatments, less than 5% of women with metastatic breast cancer will survive 5 years. This fact clearly demonstrates the necessity for exploring novel therapies outside the realm of standard treatments. These novel therapies could be used alone as treatment or to augment current treatments. Biologic therapy, or immunotherapy, is currently in its early stages of development and is being evaluated in early phase clinical trials for the treatment of breast cancer.
Vaccines are one type of biologic therapy that directly utilize the body’s immune system to recognize and kill cancer cells while sparing healthy cells from destruction. The process of biological vaccines works as follows: first, breast cancer cells are removed from the patient. Next, small proteins, called antigens, that are displayed specifically on the surface of breast cancer cells, are isolated in a laboratory. These antigens are then injected back into the patient. The patient’s immune system recognizes these unique antigens as “foreign” and initiates an immune attack on any cells in the body displaying these antigens – including the existing breast cancer cells. Through mechanisms not fully understood at present, the re-introduction of breast cancer cell antigens through injection stimulates the immune system to attack the existing cancer cells in the body.
In a recent clinical trial, researchers from several United States medical centers evaluated a new vaccine, called TriAb, in patients with metastatic breast cancer. The majority of women responded with elevated levels of immune cells targeted against the specific antigens. Importantly, women with the highest immune responses to the vaccines showed the highest rates of survival with no progression of their disease. These results are extremely important as they imply a direct correlation between immune system stimulation and survival in patients with metastatic breast cancer.
These preliminary findings are encouraging as they imply extended treatment options which are necessary to improve upon present overall survival in patients with metastatic breast cancer. Further clinical trials are needed to refine this process, with future treatment progress dependent on participation in these trials. Patients with metastatic breast cancer may wish to speak with their physicians about the risks and benefits of participating in a clinical trial further evaluating biological vaccines. Two sources of information about ongoing clinical trials include listing services provided by the National Cancer Institute (cancer.gov) andeCancerTrials.com. eCancerTrials.com also provides personalized clinical trials searches on behalf of patients. (Proceedings from the American Society of Hematology, 42nd annual meeting, Vol 96, No 11, Abstract No 3645, pp 844a, 2000)
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