Herceptin® Increases Pathologic Response Rates Among Breast Cancer Patients

Addition of Herceptin® Significantly Increases Pathologic Complete Response Rates Among Breast Cancer Patients

According to the results of a study recently published in the Journal of Clinical Oncology, the addition of Herceptin® (trastuzumab) to chemotherapy significantly increased the pathologic complete response (pCR) rate among HER2-positive breast cancer patients. Longer follow-up will reveal if a greater pCR results in overall improved survival.

Breast cancer is diagnosed in over 200,000 women annually in the United States alone. Early breast cancer refers to cancer that has not spread outside the breast and regional lymph nodes. Standard treatment for early breast cancer often includes the surgical removal of the cancer followed by chemotherapy and radiation. Long-term outcomes are promising overall for patients with early breast cancer who are treated with standard therapy. However, a significant portion of patients may experience a cancer recurrence, which is ultimately responsible for deaths caused by breast cancer.

The HER2 pathway is associated with growth and replication of cancer cells. Some cancer cells over-express HER2, and are referred to as HER2-positive. Herceptin® is a monoclonal antibody that is targeted against the human epidermal growth factor-2 (HER2) pathway. Herceptin® binds to distinct components of HER2-positive cells and disrupts cellular replication. The addition of Herceptin® to chemotherapy has demonstrated improved outcomes, including survival, in patients with HER2-positive metastatic breast cancer and studies are ongoing to evaluate Herceptin® in different stages of the disease. Herceptin® is currently approved for treatment as a single agent in patients with HER2-positive metastatic breast cancer that has progressed or recurred following prior therapy, or in combination with the chemotherapy agent paclitaxel (Taxol®) in patients with HER2-positive metastatic breast cancer who have not received prior therapy. Several clinical trials are ongoing to evaluate Herceptin® in different stages of breast cancer, including its use as neoadjuvant treatment for breast cancer.

Neoadjuvant therapy refers to treatment that is administered prior to surgery. The concept behind neoadjuvant therapy is that the cancer will shrink enough so that more complete removal of the cancer may occur. In addition, neoadjuvant therapy may immediately kill cancer cells that may have spread in the body, which could be beneficial compared to postponing systemic therapy until the patient heals from surgery.

The focus of this recent study was to determine if the addition of Herceptin® to chemotherapy for neoadjuvant therapy would improve the complete pathologic response rate (no evidence of cancer upon laboratory analysis) among women with HER2-positive breast cancer. Researchers planned to recruit 164 patients with breast cancer who were candidates for surgery and were determined to have HER2-positive disease. Each patient was randomized to receive 4 cycles of paclitaxel followed by fluoruoracil, epirubicin, and cylcophosphamide with or without weekly Herceptin® for 24 weeks. The researchers set a goal of 20% improvement in pCR among the patients receiving Herceptin®.

The trial was stopped after 34 patients had completed therapy because of the superior benefit experienced by the patients who had received Herceptin® with chemotherapy. Results of the study, based on 42 patients, indicated that the pCR rate among the patients who received chemotherapy alone was 25%, compared to 66.7% among the patients who received chemotherapy and Herceptin®. The safety of this regimen was not established; however, no clinical evidence of congestive heart failure was observed. Five patients in the chemotherapy alone treatment group experienced a decrease of their cardiac function of >10%, compared to 7 seven patients in the Herceptin® plus chemotherapy group.

Researchers concluded that despite the small study size, the addition of Herceptin® to chemotherapy significantly improved the pCr rate among HER2-positive breast cancer patients. In addition, although the safety of this regimen was not officially established, no evidence of clinical congestive heart failure was experienced among the patients.

Reference: Buzdar A, Ibrahim N, Francis D, et al. Significantly Higher Pathologic Complete Remission Rate After Neoadjuvent Therapy With Trastuzumab, Paclitaxel, and Epirubicin Chemotherapy: Results of a Randomized Trial in Human Epidermal Growth Factor Receptor 2-Positive Operable Breast Cancer. Journal of Clinical Oncology. 2005: published online ahead of print Feb 28, 2005.

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