Monoclonal antibodies: old and new trends in breast cancer imaging and therapeutic approach.

Over the last two decades, various research protocols were applied for scintigraphic imaging, prognosis and treatment of breast cancer, using monoclonal antibodies. Monoclonal antibodies approved by the United States Food and Drug Administration (FDA) include the anti-carcinoembryonic antigen (CEA), and B72.3, prepared against the tumour-associated glycoprotein, TAG-72. The recombinant humanized "cold" anti-HER2 monoclonal antibody (trastuzumab), which targets oncogene receptor HER2 has hitherto been the only monoclonal antibody widely used for the treatment of breast cancer in the USA, with or without chemotherapy. Trastuzumab is constructed against the HER2 oncogene receptor (also known as neu or c-erb-B2), which is overexpressed in 25%-30% of breast cancer cell lines and is associated with poor prognosis. Immuno-lymphoscintigraphy is also applied to guide and monitor the effect of treatment regimes. Radiolabelled, "hot" monoclonal antibodies are currently being applied for the treatment of primary or metastatic breast cancer, in experimental, pre-clinical, or clinical trials, in combination with traditional external beam radiotherapy and/or chemotherapy. Radioimmunotherapy comprises systemically administered monoclonal antibodies, linked to high-energy, beta-emitting radionuclides. Radioactive antibodies, in the form of yttrium-90 (90Y)-BrE-3, 90Y- m170 and 131I- or 90Y- labelled L6 antibody, are applied with adjuvant autologous peripheral blood stem cells transfusion, to prevent myelotoxicity. Partial or rarely complete responses to "hot" antibody treatment, of breast cancer have been reported. Innovative strategies using this combined-modality treatment hold promise for better disease-free and survival rates.