FDA Approves Test to Identify Candidates for Breast Cancer Drug - NCI Cancer Bulletin for May 3, 2011 - National Cancer Institute

FDA Approves Test to Identify Candidates for Breast Cancer Drug

The Food and Drug Administration (FDA) has approved a genetic test that doctors can use to help identify women with breast cancer who have extra copies of the HER2 gene and therefore may benefit from the drug trastuzumab (Herceptin).

Trastuzumab targets the protein made by the HER2 gene, which is located on chromosome 17. Approximately 25 percent of breast cancers have extra copies of the HER2 gene and produce higher levels of the HER2 protein. These tumors tend to grow faster and are more likely to recur than tumors that don’t overexpress HER2.

The test, called Inform Dual ISH, allows medical providers to count the copies of the HER2 gene in a tumor sample. The sample is stained so that the HER2 gene and chromosome 17 appear as different colors, allowing a lab technician to assess whether extra copies of the HER2 gene are present. The color changes can be seen under a standard microscope, whereas HER2-amplification measurements have traditionally only been available using fluorescence microscopes.

“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 Dr. Alberto Gutierrez, who directs the FDA’s Office of In Vitro Diagnostic Device Evaluation and Safety, in a statement.

According to the statement, the approval was based on a U.S. study involving tumor samples from 510 patients with breast cancer. The test correctly confirmed that a tumor sample contained extra copies of the HER2 gene in 96 percent of the HER2-positive tumor samples.

In addition, the test correctly excluded the possibility that extra copies of the gene were present in 92.3 percent of the HER2-negative tumor samples. These patients generally are not considered to be candidates for treatment with trastuzumab.

In another study of the test, researchers concluded the dual-color technique is “a reliable and robust” method for determining whether extra copies of the HER2 gene are present in cells.

The test is manufactured by Ventana Medical Systems, based in Tuscon, AZ.

NCI Cancer Bulletin for May 3, 2011 - National Cancer Institute