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FDA Approves Genetic Test for Breast Cancer Treatment

DNA strand (Genome.gov)

(Genome.gov)

The Food and Drug Administration (FDA) approved a new genetic test that will help health care professionals determine if women with breast cancer are candidates for Herceptin (trastuzumab), a commonly used breast cancer treatment. The Inform Dual ISH test is made by Ventana Medical Systems, a division of the Roche Group, in Tucson, Arizona.

The Inform Dual ISH test measures the number of copies of the HER2 gene — located on chromosome 17 in human cells — in tumor tissue. An excessive amount of the protein produced by the gene is found in some types of cancer cells, including breast cancer cells.

With the test, lab personnel can count the number of copies of HER2 genes on chromosome 17 in a small sample of the breast tumor. The sample is stained with chemicals that cause copies of HER2 genes and chromosome 17 to change color. Copies of the HER2 gene appear black and copies of chromosome 17 appear red, which can be seen under a standard microscope. Earlier technologies required fluorescence microscopes.

FDA says it based approval of the Inform Dual ISH test on a U.S. study of tumor samples from 510 patients with breast cancer. The study showed that the test confirmed that a patient’s tumor sample contained more than the normal number of copies of the HER2 gene in 96 percent of the HER2 positive tumor samples. Patients with more than the normal number of copies of the HER2 gene are considered candidates for Herceptin therapy.

The study also showed that the test excluded the possibility that more than the normal number of copies of the HER2 gene were present in 92 percent of the HER2 negative tumor samples. Patients who do not have more than the normal number of copies of the HER2 gene are typically not candidates for Herceptin therapy.

The ability to identify patients who are HER2-positive is a useful tool for physicians who considering treatment with Herceptin for their breast cancer patients. Herceptin is marketed by Genentech, also a division of the Roche Group, in South San Francisco, California.

Read More: Engineers Build Compact Diagnostic Biosensor

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