Targeted therapy of cancer refers to the use of a therapeutic that is intended to kill only a specific cell type with minimal harm to normal healthy cells.

One of the earliest successes was Herceptin for certain types of breast cancer and Gleevec for certain types of leukemia. In both cases, patients who would have otherwise died survived and the side effects were much less than older chemotherapy and radiation treatments.

Success depends on identifying a specific molecule that uniquely characterizes the malignant state of the cells that need to be destroyed and the killing drug binds to that target only, not to any of the many other potential targets that are on normal cells.