Trastuzumab, a humanized monoclonal antibody, interferes with the HER2/neu receptor and is mainly used to treat certain breast cancers, especially HER2-positive metastatic breast cancer. Combined with chemotherapy, trastuzumab increases both survival and response rate.There are four closely related receptor tyrosine kinases in the ErbB family of receptors: EGFR (ErbB-1, HER1 in humans), HER2/c-neu (ErbB-2), Her 3 (ErbB-3) and Her 4 (ErbB-4). Bound by members of the epidermal growth factor family (EGF-family) of extracellular protein ligands, the HER receptors embedded in the cell membrane promote cell growth and division by turning genes on and off. The HER2 pathway stimulates cell proliferation if it normally functions, when HER2 is overexpressed, cell growth accelerates beyond its normal limits, which happens in some cancers, notably certain types of breast cancer.
