[Herceptin, a monoclonal humanized antibody anti-HER2: a major therapeutic progress in breast cancers overexpressing this oncogene?].

HER2 is overexpressed in about 25% to 30% of breast cancers and associated with poor prognosis, resistance to hormonotherapy and lack of sensitivity to CMF-based adjuvant chemotherapy. Herceptin (trastuzumab), a humanized monoclonal antibody, administered as a single agent, produces objective responses in phase II trials in patients with metastatic breast cancers overexpressing HER2. It has shown a substantial benefit in a phase III trial which compares a standard first line chemotherapy (doxorubicin and cyclophosphamide or taxol alone) to the same chemotherapy with Herceptin in metastatic breast cancer. The Herceptin arm had significantly higher response rate (+ 53%), an improvement in the median duration of response (+ 57%) as well as in time to progression (+ 65%) compared to chemotherapy alone.