Trastuzumab

Use

Trastuzumab (Herceptin, humanized) is an MAb engineeredfrom the human epidermal growth factor receptor type 2(HER2) protein. This MAb is a human–murine immunoglobulin.It contains human structural domains (framework) andthe CDR of a murine antibody (4D5) that binds specifically toHER2. IgG1 κ is the type structure, and the antibody is monoclonal.The protein inhibits the proliferation of human tumorcells that overexpress HER2.Trastuzumab is indicated for use as a single agent for thetreatment of patients with metastatic breast cancer whose tumorsoverexpress the HER2 protein and who have not receivedchemotherapy for their metastatic disease.The HER2 proto-oncogene encodes a transmembrane receptorprotein of 185 kDa that is structurally related to theepidermal growth factor receptor HER2. Overexpression ofthis protein is observed in 25% to 30% of primary breastcancers. Trastuzumab binds with high affinity to the extracellulardomain of HER2. It inhibits the proliferation ofhuman tumor cells that overexpress HER2. Trastuzumabalso mediates the process of antibody-mediated cellular cytotoxicity(ADCC). This process, leading to cell death, ispreferentially exerted on HER2-overexpressing cancer cellsover those that do not overexpress HER2.