A new study using Bayer Diagnostics’ Serum HER-2/neu Test demonstrated metastatic breast cancer (MBC) patients whose serum HER-2/neu levels decreased by less than 20% experienced decreased benefit from trastuzumab-based therapy.  The data was from a pooled analysis of seven clinical trials in the United States and Western Europe of MBC patients who received trastuzumab (with or without chemotherapy. The Serum HER-2/neu Test from Bayer Diagnostics is the only blood test cleared by the FDA for ongoing monitoring of changes in serum levels of HER-2/neu, a protein that helps control cell growth.

The findings allowed the 307 MBC patients who had the Serum HER-2/neu Test before and after trastuzumab-based treatment to be divided into those with a greater than 20% decrease in serum HER-2 /neu levels and those with a less than 20% decrease.  The patients whose serum HER-2/neu levels decreased by less than 20% had a lower response rate, shorter duration of response, shorter time to progression, and decreased overall survival rate.

"In this analysis, measuring serum HER-2/neu levels provided an early predictor of the outcome of trastuzumab-based therapy in MBC patients. For instance, patients with < 20% decrease in serum HER-2/neu have a decreased disease free and overall survival with trastuzumab-based therapies. Patients with < 20% should be considered for investigative agents in addition to trastuzumab. The Serum HER-2/neu Test represents a model for the future of personalized medicine in which a serum biomarker is used to direct therapy at an individual level," says Allan Lipton, MD, professor of medicine and oncology, Penn State College of Medicine, the Penn State Milton S. Hershey Medical Center, and a co-author of the pooled analysis.

The standard method for determining HER-2/neu status is by testing tissue from the primary tumor, usually involving an invasive procedure. A simple blood test to determine serum HER-2/neu levels during the course of therapy is complementary to tissue testing because continuous monitoring of serum concentrations of HER-2/neu allows physicians to follow disease progression and therapy response, thereby guiding ongoing treatment decisions. The Serum HER-2/neu Test can track a woman’s HER-2/neu level once she is diagnosed with MBC regardless of whether the treatment is hormone therapy, chemotherapy or trastuzumab-based therapy because it is a serum biomarker for HER-2/neu positive tumors.