More-Sensitive Method for Detecting Her-2/neu Protein

A new, more-sensitive method of testing breast cancer tumor tissue for the Her-2/neu protein can detect blood proteins at much lower concentrations than current methods, including the enzyme-linked immunosorbant assay (ELISA), aiding earlier diagnosis and treatment.

Professor Mark Greene and colleagues at University of Pennsylvania School of Medicine (Philadelphia, PA, USA) described the new high-throughput method in the March 2006 online issue of Nature Medicine. ELISA is a widely employed technique, which uses enzymes linked to an antigen or antibody as a marker for picking out specific proteins. The new method, called FACTT (fluorescent amplification catalyzed by T7-polymerase technique), works on a similar principle but is over 1,000 times more sensitive than ELISA.

Testing breast cancer tumor tissue for Her-2/neu is primarily used to select patients for treatment with Herceptin (trastuzumab). Herceptin targets the Her-2/neu protein. It attaches itself to the excess protein molecules and inhibits growth of the cancer. The researchers described early studies of the breast cancer marker Her-2/neu that cannot be detected by ELISA until the tumor is fairly big.

Blood samples were taken from healthy and breast cancer patients whose tumor tissue did or did not show abnormal amounts of Her-2/neu. Using the new method, patients with Her-2/neu positive breast cancers showed dramatically raised serum Her-2/neu levels, while those with Her-2/neu negative breast cancers had serum levels close to that seen in healthy controls.

With FACTT, nine out of 10 patients with Her-2/neu positive tumors had raised serum levels of Her-2/neu, and only one out of four with Her-2/neu negative tumors had an elevated level. Using ELISA, only two out of ten with Her-2/neu positive tumors had raised serum Her-2/neu levels.

Currently Herceptin is approved in the United Kingdom only for the treatment of advanced breast cancer. Professor Greene believes that FACTT technology represents a way to couple diagnosis with early treatment and thereby improve prognosis.





Related Links:
Pennsylvania School of Medicine