According to results recently presented at the 2004 annual San Antonio Breast Cancer Symposium (SABCS), the administration of the p53 protein, in addition to chemotherapy, provides high rates of anti-cancer responses in patients with locally advanced breast cancer.
Breast cancer claims the lives of approximately 40,000 women annually in the United States alone. If breast cancer is caught and treated early, prior to spread from its site of origin, cure rates are high following standard therapeutic approaches. However, once the cancer has spread, cure rates fall dramatically. Patients diagnosed with stage III breast cancer typically have one of three scenarios: 1) a primary cancer that measures less than 5cm (2 inches) in size and causes axillary lymph nodes to be attached to each other or other structures; 2) a primary cancer that is greater than 5cm (2 inches) in size and involves axillary lymph nodes; or 3) a primary cancer that is attached to the chest wall or skin. Patients with localized stage IV breast cancer have cancer that has spread from the breast, but has not invaded any vital organs such as the liver, bone or brain. Researchers are evaluating novel treatment approaches, besides chemotherapy and radiation therapy commonly used in early breast cancer, in patients with more advanced breast cancer, in an attempt to improve outcomes.
Neoadjuvant chemotherapy refers to chemotherapy that is utilized prior to the surgical removal of the cancer. Neoadjuvant therapy is becoming more widely accepted, as it shrinks the cancer prior to surgery, providing the potential of having more of the cancer removed during surgery and/or allowing for breast-conserving surgery. Neoadjuvant therapy continues to be evaluated in different stages of breast cancer, as its optimal use in terms of therapeutic schedule and regimens has not yet been determined.
One type of therapeutic approach that has been gaining momentum in clinical trials is gene therapy. One gene that has been implicated in various types of cancer is the p53 gene. The p53 gene makes protein that is responsible for stopping uncontrolled growth of a cell. One of its roles is to stop growth of a cell and initiate repair of any detected mutations or damage within the DNA of the cell. In addition, the p53 gene will direct the cell to destroy itself if a mutation or damage is detected that is beyond repair. Advexin® is a vaccine that contains very high concentrations of the p53 protein. Advexin® is administered into or near the site of cancer and has demonstrated the ability to make cancer cells more sensitive to the killing effects of chemotherapy. Advexin® is being evaluated in several different types of cancer in clinical trials.
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Researchers recently conducted a clinical trial to evaluate the combination of Advexin® and chemotherapy as neoadjuvant therapy in women with advanced breast cancer. This trial included 12 patients with stages III or local stage IV breast cancer who were treated with neoadjuvant chemotherapy consisting of Taxotere® (docetaxel) and doxorubicin (Adriamycin®) in addition to Advexin®. Following treatment, all patients had an anti-cancer response and were able to have their cancer completely surgically removed. The average reduction in cancer size following neoadjuvant therapy was 80% and the average reduction in cancer size that was in the lymph nodes was 70%. Immune cells were found at the site of cancer upon evaluation of the surgical specimen and p53 from Advexin® was found at the site of cancer 19 days following treatment. Treatment with Advexin® was generally very well-tolerated.
The researchers concluded that the addition of Advexin® to chemotherapy as neoadjuvant therapy in locally advanced breast cancer appears to provide anti-cancer benefit compared to chemotherapy alone. However, only future clinical trials directly comparing Advexin®/chemotherapy to chemotherapy alone will answer this question. Furthermore, longer follow-up is necessary to determine any survival or recurrence effects of Advexin®, although the rates of complete surgical removal of cancer appear promising. Patients diagnosed with breast cancer may wish to speak with their physician regarding the risks and benefits of participating in a clinical trial further evaluating Advexin® or other promising therapeutic approaches. Sources of information regarding ongoing clinical trials include the National Cancer Institute (cancer.gov).
Reference: Introgen Therapeutics, Inc. Addition of ADVEXIN(R) to Chemotherapy Shows Promise in Treating Locally Advanced Breast Cancer. Available at: . Accessed December 2004.