Herceptin Research Today is a free monthly online journal that collates and summarizes the latest research about Herceptin, including details on side-effects, breast cancer, treatment, therapy.

Serum HER2 extracellular domain in metastatic breast cancer patients treated with weekly trastuzumab and paclitaxel: association with HER2 status by immunohistochemistry and fluorescence in situ hybridization and with response rate.

Fornier MN, Seidman AD, Schwartz MK, Ghani F, Thiel R, Norton L, Hudis C

Breast Cancer Medicine Service, Division of Solid Tumor Oncology, Department of Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA. fornierm@mskcc.org

PURPOSE: We explored the relationship between circulating HER2 extracellular domain (ECD) and tissue HER2 status as determined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). We also examined its predictive value in a cohort of metastatic breast cancer patients treated with weekly trastuzumab and paclitaxel. METHODS: Eligible patients had pre- and post-treatment stored serum specimens and were treated on a previously reported phase II trial. Retrospective analysis evaluated: the association between pretreatment serum HER2 ECD and tissue HER2 status by IHC and FISH; and the association between change in serum HER2 ECD after 12 weeks of therapy and response proportion. RESULTS: Stored serum samples were available for 55/95 (58%) patients. Statistically significant associations were found between HER2 status as assessed by IHC and FISH, and baseline serum HER2 ECD level. Patients whose ECD normalized after 12 weeks of therapy had a higher response proportion compared with patients with persistently high ECD levels (68% versus 15%, P=0.005). A relative decline of over 55% from baseline HER2 ECD predicted response to therapy. CONCLUSION: A statistically significant association was observed between pretreatment serum HER2 ECD and tissue HER2 status as assessed by IHC and FISH. A decrease in serum HER2 ECD level was a significant predictor of response to trastuzumab-based therapy.

Published 25 January 2005 in Ann Oncol, 16(2): 234-9.
Full-text of this article is available online (may require subscription).

© 2004-2008 Herceptin Research Today. All Rights Reserved.