Perceptions of Herceptin: a monoclonal antibody for the treatment of breast cancer.

In September 1998 Trastuzumab (Herceptin) became the second monoclonal antibody approved for the treatment of a malignant condition, and the first antibody approved for the treatment of a solid tumor. It is a mouse-human chimeric antibody that produces anti-tumor effects by blocking the HER2-neu receptor, and can also interact with human immune cells to effect antibody dependent cell-mediated cytotoxicity. Pivotal trials in breast cancer showed that it has activity as a single agent in a subset of patients whose tumors greatly over-express HER2, but results were even more impressive when it was used in combination with chemotherapy. It should also prove to be useful in the treatment of subsets of patients with other adenocarcinomas whose tumors over-express HER2.