HER2 Support Group Forums - Herceptin may be effective even for low HER-2 expression(in vitro studies)

http://www.jco.org/cgi/content/abstract/24/23/3735

Trastuzumab in Combination With Heregulin-Activated Her-2 (erbB-2) Triggers a Receptor-Enhanced Chemosensitivity Effect in the Absence of Her-2 Overexpression

Javier A. Menendez, Inderjit Mehmi, Ruth Lupu
JCO Aug 10 2006: 3735-3746.

http://www.jco.org/cgi/content/full/24/23/3722

Journal of Clinical Oncology, Vol 24, No 23 (August 10), 2006: pp. 3722-3725
Can Trastuzumab Be Effective Against Tumors With Low HER2/Neu (ErbB2) Receptors?

The first article details the lab studies indicating that Herceptin+chemo might be still effective in certain cases even when HER-2 is not strongly positive.
The second article discusses this & other related findings.

If these studies were to be confirmed in patients it would give oncs who already continue to prescribe Herceptin even after it appears to loose potency more reasons to do so.