Serum her-2 ecd and it's evolving role in management of breast cancer patients

A Voss, MD R Neumann PhD

Bayer Vital GmbH, Leverkusen, Germany

AIM The determination of HER-2/neu status using immunohistochemistry (IHC) and fluorescent in-situ hybridization (FISH) is quickly becoming the standard of care in the management of breast cancer patients. In addition to the cellular membrane-associated protein measured in tissue sections, a fragment of the HER-2/neu oncoprotein, known as the extracellular domain (ECD), is found in the circulation. The HER-2/neu ECD (serum HER-2/neu) is evolving as an important method in the management of metastatic breast cancer patients. METHODS In clinical studies of chemo- and hormone therapies and in patients undergoing treatment with anti-HER-2/neu antibody (Trastzumab, HerceptinR ) we measured serum levels of HER-2/neu ECD using the FDA approved HER-2/neu ELISA from Bayer Cooperation, Tarrytown, NY, USA. RESULTS In our studies the ECD level inversely correlated with the response to chemotherapy treatment indicating that patients with elevated levels of serum HER-2/neu have a reduced susceptibility to chemotherapy with e.g. paclitaxel-doxorubicin. With regards to the effect of serum HER-2/neu elevations on the response to hormone therapy (e.g. fadrozole or letrozole) the response rate (complete response, partial response and stable disease) was twice as high in patients with normal serum HER-2/neu levels than in patients with elevated serum HER-2/neu levels. Patients being positive for HER-2/neu by IHC are eligible for treatment with anti-HER-2/neu antibodies (Trastuzumab, HerceptinR). In our studies serum HER-2/neu concentrations paralleled the clinical course of patients with metastatic breast cancer receiving Trastuzumab. CONCLUSION The body of data collected to this point indicates that monitoring a patient´s serum HER-2/neu status in real time can provide important information for therapeutic decisions.

KEY WORDS: treatment outcome, Trastuzumab.

For more information, contact

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Novel Therapies, Part 1.