Oncologist now have another weapon to add to their breast cancer armamentarium with the addition of a test that can help to determine if a patient is likely to respond well to Herceptin, a drug developed by Genentech (South San Francisco) and FDA-approved for the adjuvant treatment of HER2-overexpressing, node-positive or node-negative breast cancer.

Invitrogen (Carlsbad, California) has received FDA PMA approval for its Spot-Light HER2 CISH Kit to help in the assessment of breast cancer patients for whom Herceptin treatment is being considered.

The approval is a significant marker for the company since it is the first PMA won by Invitrogen, thus giving it a first step in a different direction. Invitrogen previously has specialized in products for the research community in the U.S. rather than those for clinical use.

"The PMA approval is a milestone for us. We plan to launch in the U.S. during the second half of August," Brett Williams, senior director of cellular analysis and Invitrogen's molecular probes unit, told Medical Device Daily. "We already sell this kit outside of the U.S. There are reimbursement codes — those used for other in situ tests — already in place, and it will be priced at $1,400 for 20 assays, or $70 per test."

The current protocol to assess HER2 gene status is for labs to initially screen tissue samples with immunohistochemistry to gauge whether there is an over-abundance of the HER2 protein, as an indirect measure of gene amplification. If a test is inconclusive, the samples are typically sent to an outside lab for confirmation.

Because the Spot-Light HER2 CISH Kit doesn't need specialized equipment, any histology lab can now assess amplification of the HER2 gene while simultaneously examining tissue morphology.

The Spot-Light HER2 CISH Kit is based on a technology called chromogenic in situ hybridization (CISH). It uses a DNA probe for the HER2 gene, which is amplified in 18% to 30% of breast cancers and so predicts whether a breast cancer patient is a candidate for trastuzumab treatment. Current medical practice requires that all patients considered for trastuzumab treatment be tested for HER2 amplification or over-expression.

CISH test results are visualized under a standard bright-field microscope, as opposed to fluorescent in situ hybridization tests, known as FISH, in which the results must be visualized using a fluorescent microscope. This specialized microscope frequently requires that the analysis is done at a reference lab. In addition, HER2 CISH test results are quantifiable, removing the subjectivity inherent in tests based on immuno-histochemistry interpretation, according to Invitrogen.

"The test is designed to be used at anatomical pathology labs," Williams said. "The same folks who would look at a biopsy from a breast tumor would put a tissue slice on a slide. With this test, you look at gene copy number instead of protein levels but you do it on the same tissue. In fact, both tests can be done."

He added that the slides can then be stored for future reference, whereas slides that require the fluorescent examination can't be reviewed again.

Williams estimates that the potential market for use of this product includes roughly 240,000 patients who get breast cancer each year, of which one-third are eligible for Herceptin.

Last month, Invitrogen and Applera (Foster City, California) reported that they plan to merge in a cash-and-stock deal valued at $6.7 billion, that deal expected to close this fall. Invitrogen will acquire all of the outstanding shares of Applera's Applied Biosystems group to form a combined company, Applied Biosystems, in Carlsbad (MDD, June 13, 2008).