Women with breast cancer that contains a protein called HER2 may be treated with drugs that target this protein, such as trastuzumab (Herceptin®) or the investigational drug lapatinib (Tykerb®). In some women who receive these treatments, breast cancer stops responding to the therapy and may continue growing. But doctors do not understand why.
Investigators want to understand why therapy directed against HER2 stops working in certain patients. In laboratory studies, tumors become resistant in several ways. Specific molecules seem to change, and this may explain why therapy is no longer effective. However, doctors do not know if the same molecules change in different patients.
In this study, researchers will examine blood and tumor samples from women with HER2-positive breast cancer to see if they can identify the molecular changes underlying the development of resistance to anti-HER2 therapies. The results may enable them to offer better treatments to women with breast cancer in the future.