WASHINGTON - Genentech Inc.'s Herceptin stands to become the first approved cancer therapy based on the underlying genetic cause of the disease. But effective use of Herceptin will depend on identifying patients who over-express the HER2 gene and developing a better understanding of the relationship between HER2 expression and the treatment.

Both the treatment and a supporting assay received FDA advisory committee endorsement last week. First, the Oncologic Drugs Advisory Committee (ODAC) endorsed the safety and efficacy of GNE's Herceptin trastuzumab monoclonal antibody for treatment of metastatic breast cancer in women who over-express the HER2 gene (see BioCentury Extra, Sept. 3).