The future 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. The optimal use of all of these agents is being actively studied.
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.
Researchers at Memorial Sloan Kettering are evaluating other new classes of drugs, including novel hormone therapies targeting the male hormone (androgen) receptor, PARP inhibitors that target the type of chromosome repair activity that is more prominent in some kinds of breast cancer, and newer forms of chemotherapy that target specific components of a cancer cell's functions.