Targeted therapy uses drugs to target specific molecules (for example, proteins) on the surface of or inside cancer cells. These molecules help send signals that tell cells to grow or divide. By targeting these molecules, the drugs stop the growth and spread of cancer cells while limiting harm to normal cells.
Targeted cancer therapies use different types of drugs, and each drug works differently. Researchers are studying different targeted cancer therapies in animals (preclinical testing) and in humans (clinical trials). However, few targeted therapies have been approved to treat cancer. Targeted cancer therapies may eventually prove to be more effective and less harmful than current cancer treatments.
Targeted therapy is also called molecularly targeted therapy.
Cells send and receive chemical and molecular signals. These signals tell cells to grow, reproduce, stop reproducing or die. Usually, the signals are clear, and cells grow, divide to produce more cells and die as the body needs. Sometimes the signals get mixed up and this process is changed. Instead of dying, cells continue to grow and divide out of control. Cancer can develop when the signals cause a cell to grow and reproduce too much.
Targeted therapies block the action of specific molecules involved in cancer cell growth. Some targeted therapies focus on molecules that tell cancer cells to grow and divide out of control.
Different types of targeted therapies target different molecules. These molecules are usually involved in cell growth or division.
Tyrosine kinases are a type of enzyme (proteins that speed up certain chemical reactions in the body). They play an important role in cell development and division. Tyrosine kinase inhibitors block specific tyrosine kinases that tell cancer cells to grow. These drugs are also called signal-transduction inhibitors or small-molecule drugs.
Examples of tyrosine kinase inhibitors include:
The natural process (a series of programmed events) that cells go through when they die is called apoptosis. In some cancer cells, the signals that tell cells to go through apoptosis don’t work properly. Apoptosis-inducing drugs help restore these signals and tell the cancer cells to die. These drugs interfere with certain proteins or enzymes involved in cell growth and survival. Apoptosis-inducing drugs can also make cancer cells more vulnerable to the effects of chemotherapy.
Examples of apoptosis-inducing drugs include:
Some biological therapies specifically interfere with cancer cell growth and don’t affect normal cell growth. These biological therapies are considered targeted therapies.
Examples of biological targeted therapies include:
Targeted therapies may be used alone or with other types of therapy, such as chemotherapy. Targeted therapy can be given in different ways. For example, it may be given as pills or capsules that are swallowed (orally) or by needle into a vein (intravenously).
Some targeted therapy drugs must be given in the hospital. Others can be taken at home. Targeted therapy treatment is based on a set schedule, or protocol, that is based on the person’s specific condition. Each course of treatment usually involves a treatment period followed by a recovery period.
Side effects can occur with any type of treatment, but not everyone has them or experiences them in the same way. Side effects of targeted therapy will depend mainly on the:
Side effects can happen any time during, immediately after or a few days or weeks after targeted therapy. Most side effects of targeted therapies are mild and go away once the body gets used to the drug.
It is important to report side effects to the healthcare team. Doctors may grade (measure) how severe certain side effects are. If side effects are severe, therapy may be temporarily stopped, doses may be adjusted or both.
For more detailed information on specific drugs, go to sources of drug information.