Targeted Cancer Therapies: Questions and Answers
- Targeted cancer therapies use drugs that block the growth and spread of cancer by interfering with specific molecules involved in carcinogenesis (the process by which normal cells become cancer cells) and tumor growth (see Questions 1, 2, and 3).
- Because scientists call these molecules “molecular targets,” therapies that interfere with them are sometimes called “molecular-targeted drugs,” “molecularly targeted therapies,” or other similar names (see Question 1).
- The National Cancer Institute's Molecular Targets Development Program is working to identify and evaluate molecular targets (see Question 6).
1. What are targeted cancer therapies?
Targeted cancer therapies use drugs that block the growth and spread of cancer. They interfere with specific molecules involved in carcinogenesis (the process by which normal cells become cancer cells) and tumor growth. Because scientists call these molecules “molecular targets,” these therapies are sometimes called “molecular-targeted drugs,” “molecularly targeted therapies,” or other similar names. By focusing on molecular and cellular changes that are specific to cancer, targeted cancer therapies may be more effective than current treatments and less harmful to normal cells.
Most targeted cancer therapies are in preclinical testing (research with animals), but some are in clinical trials (research studies) or have been approved by the U.S. Food and Drug Administration (FDA). Targeted cancer therapies are being studied for use alone, in combination with each other, and in combination with other cancer treatments, such as chemotherapy.
2. What are some of the cellular changes that lead to cancer?
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place. Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor. The cells in malignant (cancerous) tumors are abnormal and divide without control or order. They can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and spread to other parts of the body.
Normal cell growth and division are largely under the control of a network of chemical and molecular signals that give instructions to cells. Genetic alterations (changes) can disrupt the signaling process so that cells no longer grow and divide normally, or no longer die when they should. Alterations in two types of genes can contribute to the cancer process. Proto-oncogenes are normal genes that are involved in cell growth and division. Changes in these genes lead to the development of oncogenes, which can promote or allow excessive and continuous cell growth and division. Tumor suppressor genes are normal genes that slow down cell growth and division. When a tumor suppressor gene does not work properly, cells may be unable to stop growing and dividing, which leads to tumor growth.