A current focus of breast cancer research is to find drugs that work by targeting specific molecules involved in breast cancer development. For example, some breast cancer cells have an overactive HER2/neu gene, which causes overproduction of the HER2/neu protein, leading to more-aggressive tumors. Drugs that inactivate the HER2/neu protein are usually given in combination with other anticancer drugs. Some targeted therapies, including trastuzumab (Herceptin®) and lapatinib (Tykerb®), are already in use.
In addition to HER2, there are other known or potential targets for drugs, some of which are available while others are in development. The formation of new blood vessels, which tumors require to grow, can be blocked by bevacizumab (Avastin®) or by newer oral drugs. We are actively studying the optimal use of all of these agents.
Rarely, trastuzumab can cause chills or fever and temporary weakening of the heart’s pumping function. Lapatinib can cause rashes, diarrhea, or liver dysfunction in some women. Common side effects of drugs that interfere with blood vessel growth can include rash, kidney function problems, and high blood pressure.