A monoclonal antibody as an effective therapeutic agent in breast cancer: trastuzumab

Trastuzumab (Herceptin^®; Genentech, Inc., CA, USA) is a humanised monoclonal antibody developed to target the HER-2/neu receptor, which is overexpressed in 20 – 25% of breast carcinomas. Clinical studies showed that trastuzumab is effective as single-agent therapy and that it has greater antitumour activity in combination with chemotherapy than chemotherapy alone in metastatic breast cancer. The indication for trastuzumab monotherapy and the combination with various chemotherapy agents is country-specific and is largely based on trials of efficacy and safety. Patients with a HER-2/neu overexpression level of 3+, determined by immunohistochemical assay or amplification using fluorescence in situ hybridisation, derive most clinical benefit from trastuzumab. Trastuzumab is generally well-tolerated. Cardiotoxicity is the main concern; thus, monitoring of cardiac function is recommended. Ongoing trials investigate the role of trastuzumab in the adjuvant and neoadjuvant settings.