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Targeted Therapy is a Smart Bomb in the War Against Cancer

John Burfeind, M.D., Medical Oncologist, Columbia St. Mary’s

Posted: March 1, 2006

Targeting cancer at the molecular level is proving to be an effective treatment that causes fewer side effects than traditional chemotherapy. Targeted molecular therapy, or simply “targeted therapy,” is a groundbreaking development in the medical treatment of cancer. Because of targeted therapy, major advances in fighting cancer are occurring at Columbia St. Mary’s and elsewhere, putting us on the front lines in the war against cancer.

Targeted therapy is the development of designer drugs that attack cancer at a very specific molecular location. Cancer develops because of certain cellular changes. Normally, cells grow and divide to form new cells as the body needs them. Old cells eventually die and new cells take their place. But sometimes this process goes wrong and new cells form when the body doesn’t need them, or old cells don’t die when they should. These extra cells can form a tumor. If the tumor cells are malignant, they divide out of control and can attack nearby tissues and organs. Some can break away from the malignant tumor and spread cancer to other parts of the body by way of the bloodstream.

Traditional chemotherapy has been used to treat malignancies for the past 40 years, and indeed, continues to be used today. Traditional chemotherapy drugs are quite toxic. These medicines are effective because they destroy rapidly dividing cells, which is exactly what cancer cells are. But they are indiscriminate and can damage other tissues such as the cells lining the intestines and bone marrow cells. As a result, there are usually side effects such as nausea and the lowering of blood counts.

Targeted therapy hopes to improve on traditional chemotherapy by using drugs that block the growth and spread of cancer by interfering with specific molecules that change normal cells into cancer cells. This therapy often focuses on proteins that are involved in a cell’s signaling process. By blocking the signals that trigger the growth and uncontrolled division of cancer cells, targeted therapy helps stop that growth and division. This is important because it enhances the drug’s ability to stop the cancer, and it minimizes the effect on the rest of the body. Targeted therapy is like a smart bomb in the war against cancer.

The use of targeted therapy began making big strides in the late-1990s. Researchers had been making progress in learning about the molecular basis of cancer for years, and by the late-1990s their labors began paying off. In 1997 Rituxan was the first targeted therapy drug to become FDA-approved. It is used to combat lymphoma. The following year Herceptin was approved for the treatment of breast cancer. And two years after that, Gleevec showed outstanding results in the treatment of chronic myeloid leukemia, so much so that it was featured on the cover of Time magazine in May 2001. In part due to targeted therapy advances, the life expectancy of patients with advanced colon cancer has more than doubled over the last few years.

It is very important to keep in mind that traditional chemotherapy is still highly effective, and in most cases is still more effective than targeted therapy. Most of the time when targeted therapy is used today, it is used in combination with traditional chemotherapy.

While some targeted therapy medications are widely used already, many are in clinical trials approved by the U.S. Food and Drug Administration (FDA) involving cancer patients, and others are in preclinical testing on animals. These drugs are being studied for use alone, in combination with other targeted therapy drugs, and in combination with traditional chemotherapy. Every few months oncologists hear about new targeted therapy drugs that are undergoing further study.

Medical oncologists are optimistic about the future of targeted therapy and believe we’re at the dawn of an exciting new era. Targeted therapy will hopefully provide doctors with a better way of tailoring cancer treatments to individual patients. Eventually cancer treatment may be individualized based on each patient’s unique set of molecular targets. And who knows, maybe some day in the distant future well-tolerated targeted therapy medications may replace traditional chemotherapy drugs.

John Burfeind, M.D.
Medical Oncologist
Columbia St. Mary’s
Northpoint Medical Clinic
414-291-1500

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