A targeted therapy is one that is designed to treat only the cancer cells and minimize damage to normal, healthy cells. Cancer treatments that “target” cancer cells may offer the advantage of reduced treatment-related side effects and improved outcomes.
Conventional cancer treatments, such as chemotherapy and radiation therapy, cannot distinguish between cancer cells and healthy cells. Consequently, healthy cells are commonly damaged in the process of treating the cancer, which results in side effects. Chemotherapy damages rapidly dividing cells, a hallmark trait of cancer cells. In the process, healthy cells that are also rapidly dividing, such as blood cells and the cells lining the mouth and GI tract are also damaged. Radiation therapy kills some healthy cells that are in the path of the radiation or near the cancer being treated. Newer radiation therapy techniques can reduce, but not eliminate this damage. Treatment-related damage to healthy cells leads to complications of treatment, or side effects. These side effects may be severe, reducing a patient’s quality of life, compromising their ability to receive their full, prescribed treatment, and sometimes, limiting their chance for an optimal outcome from treatment.
Advances in science and technology have led to the development of several different types of targeted therapies. Each of these new treatments targets cancer through different mechanisms:
Anti-angiogenic drugs starve the cancer cells of blood that they need to survive and grow.
Monoclonal antibodies can locate cancer cells in the body by recognizing proteins that are more abundant in cancer cells than normal cells, called receptors. The monoclonal antibody may then cause its anti-cancer effect by blocking the receptor from binding with substances in the blood. Treatments that block receptors may also be called “receptor antagonists” .
Radioactive monoclonal antibodies are comprised of a radioactive substance attached to a monoclonal antibody, the latter of which acts as a homing device, and the radioactive substance kills the targeted cell.
Tyrosine kinase inhibitors interact with the enzyme (protein) tyrosine, which is active in a complex signaling system that is used by some cancers as a survival mechanism to allow them to grow out of control. The drug Gleevec® (imitinib mesylate) is an example of this type of targeted therapy that inhibits a mutated form of tyrosine kinase and stops the abundant growth of cancerous white blood cells in chronic myeloid leukemia.
Vaccines are made from a patient’s own cancer cells and stimulates the body to recognize and attack cancer cells.