About HER2
Human epidermal growth factor receptor 2 (HER2) is a transmembrane protein that plays a pivotal role in growth factor signal transduction.1-3 HER2 is part of the HER family, which includes four growth factor receptors: HER1 (also known as epidermal growth factor receptor [EGFR]), HER2, HER3, and HER4.4
In preclinical studies, HER2 was shown to regulate a complex signal transduction cascade that influences many cellular processes, including cell cycle progression, cell survival, cell proliferation, and cell motility.3

HER2 Overexpression
HER2 protein overexpression can result in malignant transformation of cells.3 The relationship between HER2 overexpression and tumorigenesis is best understood in breast cancer, but is also acknowledged as a clinically important biomarker in gastric and gastroesophageal junction cancers.5-9
In the ToGA* trial, approximately 22% of screened patients with metastatic gastric and GEJ cancer had tumors that overexpressed HER2.5
*Trastuzumab for gastric cancer trial.
References
- Bang Y-J, Van Cutsem E, Feyereislova A, et al; for the ToGA Trial Investigators. Trastuzumab in combination with chemotherapy versus chemotherapy alone for treatment of HER2-positive advanced gastric or gastro-oesophageal junction cancer (ToGA): a phase 3, open-label, randomized controlled trial. Lancet. 2010;376:687-697.
- Coussens L, Yang-Feng TL, Liao Y-C, et al. Tyrosine kinase receptor with extensive homology to EGF receptor shares chromosomal location with neu oncogene. Science. 1985;230:1132-1139.
- Gravalos C, Jimeno A. HER2 in gastric cancer: a new prognostic factor and a novel therapeutic target. Annals Oncol. 2008;19:1523-1529.
- Hofmann M, Stoss O, Büttner R, et al. Assessment of a HER2 scoring system for gastric cancer: results from a validation study. Histopathology. 2008;52:797-805.
- Koeppen HKW, Wright BD, Burt AD, et al. Overexpression of HER2/neu in solid tumours: an immunohistochemical survey. Histopathology. 2001;38:96-104.
- Park DI, Oh SJ, Sohn CI, Yoo CH, Chae SW, Ryu SH. HER2/neu amplification is an independent prognostic factor in gastric cancer. Dig Dis Sci. 2006;51:1372-1379.
- Slamon DJ, Godolphin W, Jones LA, et al. Studies of the HER-2/neu proto-oncogene in human breast and ovarian cancer. Science. 1989:244:707-712.
- Tanner M, Hollmén M, Junttila TT, et al. Amplification of HER-2 in gastric carcinoma: association with Topoisomerase IIα gene amplification, intestinal type, poor prognosis and sensitivity to trastuzumab. Annals Oncol. 2005;16:273-278.
- Yarden Y, Sliwkowski MX. Untangling the ErbB signalling network. Nature Rev Molecular Cell Biology. 2001;2:127-137.
Herceptin MOA
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Herceptin (trastuzumab) is a monoclonal antibody specifically designed to target HER2.

It is believed to block downstream signaling pathways.

Herceptin flags the tumor cell for destruction by the body's immune system, known as antibody dependent cellular cytotoxicity (ADCC).

Herceptin prevents HER2 shedding.1

Herceptin may work to enhance the effects of chemotherapy as shown in multiple pre-clinical studies.1

References
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American Cancer Society. Breast Cancer Facts & Figures 2009-2010. Atlanta: American Cancer Society, Inc. Available at: http://www.cancer.org/acs/groups/content/@nho/documents
/document/f861009final90809pdf.pdf. Accessed August 24, 2010.




