What Are Targeted Therapies?

Chemotherapy drugs work by attacking all fast-growing cells in the body. Fortunately, this includes cancer cells. Unfortunately, it also includes the rapidly multiplying but normal cells of the gastrointestinal tract, bone marrow, skin, and other organs.

For a long time, scientists have been looking for new drugs that could tell the difference between normal and cancerous cells. The search has produced results.

Targeted therapy, also called immunotherapy or biological therapy, is a promising approach to cancer treatment that is designed to target cancer cells specifically. It works differently from cell-killing chemotherapy and has different side effects.

Currently, the targeted therapy drugs that are available to treat breast cancer include drugs that target a specific protein on the surface of the cells, called HER2/neu.


Herceptin (trastuzumab) and Tykerb (lapatinib)

The first targeted therapy compound to gain acceptance in breast cancer treatment was Herceptin, a monoclonal antibody.

What exactly is a monoclonal antibody? An antibody is a protein naturally produced by the body to fight off all foreign particles. A monoclonal antibody is a protein created in a laboratory, and tailor-made to target very specific foreign particles: certain cancer cells.

To manufacture a monoclonal antibody, tumor cells from the patient are inactivated and then injected into a laboratory animal to stimulate the production of antibodies specific to that cancer. When the antibodies are removed and injected into the patient, they bypass healthy tissues, and home-in directly on the tumor cells.

Herceptin and Tykerb are engineered to interfere with a growth-promoting protein known as HER2/neu. This protein is present in abnormally high amounts on the surface of breast cancer cells in about one out of five breast cancer patients.

The side effects of Herceptin may include fever and chills, weakness, nausea, vomiting, cough, diarrhea, and headache. It can also cause reduced heart function and congestive heart failure in some patients.

Who Can Benefit From Targeted Therapy?

A sample of your tumor will be sent for a variety of tests, either right after the biopsy, or at a later date, to determine which, if any, targeted therapies could benefit you. Your physician is the only one who can advise you about the risks and expected benefits in your particular case.

The Future

Scientists are searching for new markers that will help us develop additional, and better-focused targeted therapies. Ask your doctor to review the latest findings with you.

Many experts believe that new technologies may bring new hope for effective treatment, cure, or even prevention of breast cancer.