Test Predicts Outcome of Trastuzumab Therapy

A new test measures the level of human epidermal growth factor receptor 2 (HER-2/neu) in the serum of women with metastatic breast cancer (MBC). The test is an early predictor of the outcome of trastuzumab therapy.

HER-2/neu is a protein that helps control cell growth. The standard method for determining HER-2/neu status is by testing tissue from the primary tumor, which usually involves an invasive procedure. A simple blood test to determine serum levels of HER-2/neu levels in the course of therapy is complementary to tissue testing and helps to monitor therapy response and disease progression, guiding treatment decisions. The serum HER-2/neu test tracks a woman's HER-2/neu levels regardless of whether the patient is receiving hormone treatment, chemotherapy, or trastuzumab-based therapy, because it is a serum marker for HER-2/neu positive tumors.

The Oncogene Science Group (Cambridge, MA,USA), a subsidiary of Bayer Diagnostics, manufactures the serum HER-2/neu test and provides it on its fully automated Advia Centaur immunoassay system or via the enzyme-linked immunosorbant assay (ELISA) microtiter plate. The serum HER-2/neu test has been cleared by the U.S. Food and Drug Administration (FDA) for monitoring changes in serum levels of HER-2/neu.

A study presented at the 2006 annual meeting of the American Society of Clinical Oncology demonstrated that MBC patients whose serum human epidermal growth factor receptor 2 (HER-2/neu) levels decreased less than 20% experience decreased benefit from trastuzumab-based therapy. The data, from a pooled analysis of seven clinical trials in the United States and Western Europe, were presented by Suhail Ali, M.D., associate professor, division of hematology and oncology, Pennsylvania State Milton S. Hershey Medical Center, Pennsylvania State College of Medicine (Hershey, PA, USA).

Recent clinical studies have also shown that up to 40% of breast cancer patients who had HER-2/neu-negative tumors at first diagnosis later became HER-2/neu positive. The new serum test allows physicians to identify patients whose original tissue biopsies were HER-2/neu negative, or not tested, or not available for testing, or were stored for a long period of time but subsequently became positive after the cancer had spread.



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