The FDA announced Thursday that it had approved Herceptin (trastuzumab) in combination with chemotherapy for HER2-positive, metastatic stomach cancer. The indication is reserved for newly diagnosed patients who have not yet received treatment. Herceptin was originally approved for HER2-positive breast cancer since 1998. With the understanding that HER2 overexpression fueled certain breast cancers, researchers had begun looking for other cancers that may be driven by the same mechanism. A phase 3 study presented at last year's annual meeting of the American Society of Clinical Oncology found that 20 percent of advanced stomach cancers (also called gastric cancers) also overproduce HER2, a receptor that sits on the surface of certain cancer cells. Herceptin works to block the protein from binding to the receptor, knocking out the cancer cell's growth factor--in theory, halting the tumor's growth and ultimately killing it. In the study, patients who received a combination of Herceptin and chemotherapy fared better than patients who received chemotherapy only. The median overall survival improved from 11.1 months to 13.8 months. However, researchers found that patients whose tumors overexpressed the highest levels of HER2 had a median survival of 16 months, nearly a 50 percent improvement over chemotherapy alone. You can read more about Herceptin in advanced gastric cancer in "Gut Reaction" from the Winter 2009 issue. You can also view an illustration of how Herceptin works in gastric cancer in "A New Mode of Attack."