The U.S. Food and Drug Administration recently approved a new gene New Test Approved to Determine Whether Breast Cancer Patients Would Benefit from Certain Treatment (dateline August 25, 2008) | Breast Health News | Imaginis - The Women's Health & Wellness Resource Network

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New Test Approved to Determine Whether Breast Cancer Patients Would Benefit from Certain Treatment (dateline August 25, 2008)

The U.S. Food and Drug Administration recently approved a new genetic test for determining whether patients with breast cancer are good candidates for treatment with the drug Herceptin (generic name, trastuzumab). Herceptin has been shown to be effective in helping treat breast cancer but it only works in patients with certain types of breast cancers-called HER2/neu positive breast cancer. The new test, called the SPOT-Light HER2 CISH kit, may be more convenient than the two other FDA-approved tests, the fluorescent in situ hybridization (FISH) and immunohistochemistry (IHC), because it can be performed with a standard microscope, which allows more medical facilities to perform the test. The new test can also allow laboratories to store a patient's tissue for future reference.

HER2 (human epidermal growth factor receptor 2) is a protein found on the surface of cells that, when functioning normally, has been found to be a key component in regulating cell growth. However, when the HER2 protein is altered, extra HER2 protein receptors may be produced. This over-expression of HER2 causes increased cell growth and reproduction, often resulting in more aggressive breast cancer cells. Women with HER2 over-expression may not be as responsive to standard breast cancer treatments, including certain regimens of chemotherapy.

Herceptin works by targeting breast cancer cells that have too many copies of the HER2 protein. After it has identified which cells over-express the HER2 protein, Herceptin attaches itself to the HER2 protein receptors on the surface of these cells. By binding to the cells, Herceptin slows the growth and spread of tumors that have an overabundance of HER2. Many experts believe that Herceptin represents the future direction of breast cancer drugs in that it targets a particular protein of the cancer cell and prevents it from carrying out its action. The drug, Tykerb, is newly approved by FDA and is typically used in patients who have already been treated with Herceptin.

The SPOT-Light HER2 CISH kit is a test that measures the number of copies of the HER2 gene in tumor tissue. "When used with other clinical information and laboratory tests, this test can provide health care professionals with additional insight on treatment decisions for patients with breast cancer," said Daniel Schultz, M.D., director of the FDA's Center for Devices and Radiological Health," in an FDA news release.

According to the FDA, the SPOT-Light test counts the number of HER2 genes in a small sample of removed tumor. The removed piece is stained with a chemical that causes any HER2 genes in the sample to change color. This color change can be visualized under a standard microscope, eliminating the need for the more expensive and complex fluorescent microscopes required to read assays already on the market. Unlike existing tests, the SPOT-Light allows labs to store the tissue for future reference.

The FDA's approval of the SPOT-Light test came after reviewing the results of a study using tumor samples from patients with breast cancer in the United States and Finland. According to the FDA, these studies confirmed that the test was effective in determining how many HER2 genes were in these patients.

The SPOT-Light test should be available in mid-August. Patients eligible for HER2 testing should talk to their physicians about whether this test is an option for them.

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