The US Food and Drug Administration (FDA) has just announced approval of a genetic test that will help determine which breast cancer patients will be best served by taking the drug Herceptin (trastuzumab) for treatment.  The new test, SPOT-Light HER2 CISH, measures the number of the HER2 gene in cancerous breast tissue.

Every breast cell carries two copies of the HER2 gene, which regulates cellular growth.  Some breast cancer patients have more than two copies of the gene, however, which results in uncontrolled cell growth in breast tissue.  Herceptin works on the production of the HER2 protein in a way that controls the growth of HER2 cancerous cells.

SPOT-Light counts HER2 genes in small tissue samples taken from the breast tumor.  There are similar tests currently in use but they require the use of expensive fluorescent microscopes and fresh tissue samples for each count.  SPOT-Light works with standard microscopes and works with tissue that can be stored for future reference.

FDA approval is based on research in which tissue samples from the breast tumors of cancer patients in the US and Finland were tested to determine the accuracy of the SPOT-Light test.

Invitrogen Corp, Calsbad, California, manufactures SPOT-Light and Genentech, San Francisco, California, manufactures Herceptin.

Source: FDA