New Technique Detects Early Metastasis Of Breast Cancer

Since secondary tumors, ignited by spreading malignant cells, and not the primary breast cancer tumor, are the primary cause of cancer death, early detection of metastatic spread is crucial to a woman's prognosis.

It should enable the patient's doctor to adjust the woman's treatment so that it will target the spreading cancer early, said Winfried H. Albert, Ph.D., chief scientific officer of AdnaGen, the German biotech company that developed the technology.

Albert said that the company's diagnostic tool, which is being evaluated in clinical studies at The University of Texas M. D. Anderson Cancer Center in Houston, can spot one malignant cell in a typical blood sample. A typical sample is 5 milliliters and contains over 2.5 x 1010 cells.

As a biomarker for breast cancer metastasis, cancer cells circulating in the blood system have not been easy to detect and analyze because they are a "needle in the haystack" among the millions of cells in the bloodstream.

However, Albert said that AdnaGen's technology can detect the "needle" with a specificity of 97 percent (only three "false" positive results in tests of 100 seemingly healthy people).

"Metastasis usually is detected by costly, cumbersome physical methods like computer tomography (CT)," added Albert. "We have seen cases, where our test was positive, when there was still no clinical evidence. But at a careful second look through a CT scan, small metastatic lesions have been detected."

To produce its diagnostic tool, AdnaGen links an antibody-mix to magnetic beads. This antibody-mix is tailored to home in on specific molecular features, or antigens, of the respective cancer cells.

When exposed to a blood sample, the magnetic antibody-beads capture tumor cells possessing the specified antigens. A magnetic particle concentrator then removes the tumor cells labeled with the magnetic beads, and the cells are then analyzed to identify several gene products, including potential molecular targets for a specific drug.

Using this technology, AdnaGen discovered that the genetic signatures of the breast cancer and its metastases may differ, with the circulating tumor cells reflecting the gene expression profile of the metastases.

When a metastases has been diagnosed, treatments "usually has been chosen according to the features of the primary tumor, neglecting the fact that metastases can differ considerably from them," Albert noted.

AdnaGen, which is marketing its breast cancer assay (as well as assays for colon and prostate cancer) in Europe, is awaiting the results of a clinical trial before applying for FDA approval to make the test available in the U.S.