Genetic POC Tests Identify Micrometastases

In a phase II trial, an investigational genetic test identified micrometastases in nearly one-half of colon cancer patients who showed no signs of metatastic disease by conventional methods. Another experimental genetic test demonstrated high levels of sensitivity in detecting metastatic cancer cells in the blood and other tissues of people with breast, skin, or colorectal cancer.

These point-of-care (POC) tests are based on the Origen technology of Igen International, Inc. (Gaithersburg, MD, USA) and are being developed by the John Wayne Cancer Institute (Santa Monica, CA, USA). If further studies confirm earlier results, the tests may help doctors with disease staging, says Igen.

In the phase II trial, reported in the Journal of Clinical Oncology (2001,19;4:1128-1136), doctors used sentinel node mapping to select nodes for biopsy in patients with early-stage colon cancer. The biopsy material was analyzed using the Origen-based test and other methods. The sentinel nodes of 26 patients showed no signs of metatastic cancer by the other methods, while the Origen test identified micrometastases in 12. The same test was negative, however, when used on cells from 25 healthy people and lymph nodes from five patients with benign conditions.

In another study, researchers obtained blood and other tissue from people with breast cancer, malignant melanoma, or colorectal cancer. An Origen-based multiplex assay that could detect cancer-related genes called MAGE-A was able to detect metastatic cells in the blood and other tissues of patients with any of the three cancers. The results, confirmed with DNA sequencing, were published in the Journal of Clinical Chemistry (2001;47:505-512).



Related Links:
John Wayne Cancer Institute
Igen Int'l