M. D. Anderson Study Finds Change in HER2 Status After Treatment With Herceptin
Posted Sep 09 2008 2:04am
Researchers at The University of Texas M. D. Anderson Cancer Center have discovered that when treated with Herceptin prior to surgery, 50 percent of HER2 positive, breast cancer patients showed no signs of disease at the time of surgery. However, of those women who had residual disease, about one-third had tumors that converted from HER2 positive to HER 2 negative status —possibly indicating a resistance to the targeted therapy.
The study will be presented today in advance of the American Society for Clinical Oncology Breast Cancer Symposium.
Approximately 30 percent of breast cancer cells have an excess amount of the HER2 protein on their surface, which makes the cancer more aggressive. Herceptin, also known as trastuzumab, is a monoclonal antibody that latches on to these proteins and inhibits tumor growth. It was approved in 1998 for women whose advanced, metastatic breast cancer is HER2-positive; it was approved in 2006 for use in the early setting.
It’s known that a small percentage of HER2 positive patients develop a resistance to Herceptin during treatment, and there have been several described mechanisms for Herceptin resistance, said Elizabeth Mittendorf, M.D., assistant professor in M. D. Anderson’s Department of Surgical Oncology.