The U.S. Food and Drug Administration on Tuesday approved Invitrogen Corp’s genetic test for determining whether patients with breast cancer are good candidates for treatment with the drug Herceptin.

Invitrogen’s test - the SPOT-Light HER2 CISH kit - measures the number of copies of the HER2 gene in tumor tissue. Patients who over-produce the HER2 protein are typically treated with the drug Herceptin, which is made by Genentech.

“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,” Dr. Daniel Schultz, director of the FDA’s Center for Devices and Radiological Health, said in a statement.

The Invitrogen test counts the number of HER2 genes in a small sample of removed tumor, the FDA said. The removed piece is stained with a chemical that causes any HER2 genes 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, the agency said.

Unlike existing tests, the Invitrogen test allows labs to store the tissue for future reference, the FDA said.

The drug Herceptin targets HER2 protein production and attempts to stop the growth of the HER2 cancer cells.

The FDA said it based its approval of the Invitrogen test on a study using tumor samples from patients with breast cancer in the United States and Finland. The data confirmed the test was effective in determining how many HER2 genes were present, it said.

Invitrogen, based in Carlsbad, Calif, provides technologies for disease research and drug discovery. The company had revenue of $1.3 billion in 2007.

WASHINGTON (Reuters)