Throwing stones at castle walls is one way to attack an enemy, but sneaking inside makes the target much more vulnerable. Researchers at Cedars-Sinai's Maxine Dunitz Neurosurgical Institute have employed a similar strategy using a mouse model to target important mechanisms inside the most challenging breast cancer cells. Earlier studies at Cedars-Sinai found a similar approach effective in attacking malignant brain tumor targets. Unlike other drugs that target cancer cells from outside and often injure normal cells as a side effect, this therapy consists of multiple drugs chemically bonded to a "transport vehicle." The drugs bypass healthy cells, accumulate inside tumor cells and attack molecular targets that enable cancer cells to grow and spread. Studies using a mouse model show this highly targeted approach, using combinations of drugs, to be more effective than standard treatment methods. This research targeted HER2-positive breast cancer – a type that, due to a genetic mutation, makes excessive amounts of a protein that promotes the growth of cancer cells. HER2-positive breast cancers tend to be more aggressive and less responsive to treatment than other breast cancers. One commonly used antitumor drug, trastuzumab (Herceptin®), is sometimes beneficial, but with advantages and disadvantages. It is an antibody to the HER2 antigen, which means it naturally seeks out this protein in cancers. But its effectiveness as a treatment usually is limited because in 66 to 88 percent of patients, the tumors become resistant within the first year of treatment. Herceptin also can injure normal organs it contacts. The researchers reported in their recent studies, published in the February 19, 2011 issue of Cancer Research, that the new drug carried multiple molecular components, each with a distinct role.Login Or Register To Read Full Story