30% of women with breast cancer have HER2 positive breast cancer which is more aggressive than regular breast cancer, but new drugs such as Herceptin or Lapatinib (Tykerb) or Pertuzamab will be effective in this type of cancer

HER2/neu (also known as ErbB-2) stands for "Human Epidermal growth factor Receptor 2" and is a protein giving higher aggressiveness in breast cancers. It is encoded by the ERBB2 gene.HER2 is a cell membrane surface-bound receptor tyrosine kinase and is normally involved in the signal transduction pathways leading to cell growth and differentiation. It is encoded within the genome by HER2/neu, a known proto-oncogene. The HER2 gene is a proto-oncogene located at the long arm of human chromosome 17(17q21-q22).

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Approximately 30 percent of breast cancers have an amplification of the HER2/neu gene or overexpression of its protein product. Overexpression of this receptor in breast cancer is associated with increased disease recurrence and worse prognosis.

 Because of its prognostic role as well as its ability to predict response to trastuzumab (Herceptin) breast tumors are routinely checked for overexpression of HER2/neu. Overexpression also occurs in other cancer such as ovarian cancer, stomach cancer, and biologically aggressive forms of uterine cancer, such as uterine serous endometrial carcinoma.

In clinical usage, HER2/neu is important as the target of the monoclonal antibody trastuzumab (marketed as Herceptin). Trastuzumab is effective only in breast cancer where the HER2/neu receptor is overexpressed.

Overexpression of the HER2 gene can be suppressed by the amplification of other genes and the use of the drug Herceptin. Research is currently being conducted to discover which disregulated genes may have this desired effect. Another monoclonal antibody, Pertuzumab. which inhibits dimerization of HER2 and HER3 receptors, is in advanced clinical trials. Trials combining these durgs with chemotherapy are being devloped as noted below

The NEOSPHERE study (Neoadjuvant Study of Pertuzumab and Herceptin in an Early Regimen Evaluation) is a randomized multicentre, international Phase II study that was conducted in 78 centres worldwide (except the USA) in 417 women with newly diagnosed HER2-positive early, inflammatory or locally advanced breast cancer who had never received Herceptin. Prior to surgery (neoadjuvant treatment) these women were randomized to four study arms. The primary endpoint was complete tumour disappearance at time of surgery (pathological complete response , pCR) and the results were:

  • pCR of 29,0 percent for Herceptin and docetaxel
  • pCR of 45,8 percent for Herceptin, pertuzumab and docetaxel
  • pCR of 16,8 percent for Herceptin and pertuzumab
  • pCR of 24,0 percent for pertuzumab and docetaxel