Understanding Targeted Therapy

Approved by the Cancer.Net Editorial Board, 05/2020

Targeted therapy is a cancer treatment that uses drugs to target specific genes and proteins that are involved in the growth and survival of cancer cells. Targeted therapy can affect the tissue environment that helps a cancer grow and survive or it can target cells related to cancer growth, like blood vessel cells.

Doctors often use targeted therapy along with chemotherapy and other treatments. The U.S. Food and Drug Administration (FDA) has approved targeted therapies for many types of cancers. Research is also underway to find new targeted therapy treatments.

How does targeted therapy work?

There are many types of cells that make up every tissue in your body. For example, there are blood cells, brain cells, and skin cells. Each type has its own job. Cancer starts when certain genes in healthy cells change and become abnormal over time. This change is called a genetic mutation.

Genes tell cells how to make proteins to keep the cell working. If the genes mutate, these proteins change, too. This can make cells divide too much or too quickly and allow the cells to live much longer than they normally would. When this happens, the cells grow out of control and form a tumor. Learn more about the genetics of cancer.

To develop targeted therapies, researchers first identify the genetic changes that help a tumor grow and change. A potential target for this therapy would be a protein that is present in cancer cells but not healthy cells. This can be caused by a mutation. Once researchers have identified a mutation, they develop a treatment that targets that specific mutation.

Targeted therapies can do different things to the cancer cells they target:

  • Block or turn off signals that tell cancer cells to grow and divide

  • Prevent the cells from living longer than normal

  • Destroy cancer cells

To best match the best targeted therapy for your tumor, your doctor may order tests to learn about the genes, proteins, and other factors that are unique to your tumor. This helps find the most effective treatment. Like other treatments, targeted therapies can cause side effects, so it is important that your doctor matches your tumor to the best possible treatment and dose. The dose of targeted therapy that you will receive is based on many factors, like your body weight and your risk of developing severe side effects. Talk to your health care team about why they recommended a certain dose.  

Are there different types of targeted therapy?

There are several different types of targeted therapy. The most common types are monoclonal antibodies or small-molecule drugs.

Monoclonal antibodies. Drugs called monoclonal antibodies block a specific target on the outside of cancer cells. The target might also be in the area around this cancer. Monoclonal antibodies can also send toxic substances right to cancer cells. For example, they can help chemotherapy and radiation therapy reach cancer cells better. Monoclonal antibodies are also a type of immunotherapy.

Small-molecule drugs. Drugs called small-molecule drugs can block the process that helps cancer cells multiply and spread. Angiogenesis inhibitors are an example of this type of targeted therapy. Angiogenesis is the process for making new blood vessels. A tumor needs blood vessels to bring it nutrients. The nutrients help it grow and spread. Angiogenesis inhibitors starve the tumor by keeping new blood vessels from forming in the tissue around it.

Other types of targeted therapy include other immunotherapies, angiogenesis inhibitors, and apoptosis inducers (therapies that start cell death, or apoptosis).

Some types of targeted therapies are specific to a type of cancer. Others are known as tumor-agnostic or site-agnostic treatments. They treat tumors anywhere in the body by focusing on the specific genetic change instead of the type of cell. Learn more about tumor-agnostic treatments.

Examples of targeted therapies

Targeted therapies are a rapidly growing field of cancer research and researchers are studying many new targets and drugs through clinical trials. Below are a few examples of targeted therapies that are available now. Ask your health care team for more information.

  • Breast cancer. About 20% to 25% of breast cancers have too much of a protein called human epidermal growth factor receptor 2 (HER2). This protein makes tumor cells grow. If the cancer is "HER2 positive", there are many targeted therapy options. Learn more about targeted therapy for breast cancer.

  • Chronic myeloid leukemia (CML). Almost all cases of chronic myeloid leukemia are driven by the formation of a gene called BCR-ABL. This gene leads to the production of an enzyme called the BCR-ABL protein. This protein causes normal myeloid cells to start behaving like cancer cells. This was the very first mutation and cancer treated with targeted therapy. Learn more about targeted therapy for chronic myeloid leukemia.

  • Colorectal cancer. Colorectal cancer often makes too much of a protein called epidermal growth factor receptor (EGFR). Drugs that block EGFR may help stop or slow cancer growth. These cancers have no mutation in the KRAS gene. Another option is a drug that blocks vascular endothelial growth factor (VEGF). This protein helps make new blood vessels. Learn more about targeted therapy for colorectal cancer.

  • Lung cancer. Drugs that block EGFR may also stop or slow lung cancer growth. This may be more likely if the EGFR has certain mutations. There are also drugs for lung cancer with mutations in the ALK and ROS genes. Doctors can also use angiogenesis inhibitors for some lung cancers. Learn more about targeted therapy for non-small cell lung cancer.

  • Lymphoma. In lymphoma, there is an overproduction of B cells, a type of white blood cell that fights infections. Targeted drugs that block the enzyme that leads to this overproduction of B cells have been very successful for the treatment of lymphomas and some B-cell leukemias. Learn more about targeted therapies for lymphoma.

  • Melanoma. About half of melanomas have a mutation in the BRAF gene. Researchers know certain BRAF mutations make good drug targets. So there are many FDA-approved BRAF inhibitors. But these drugs can be harmful if your tumor do not have the BRAF mutation. Learn more about targeted therapy for melanoma.

The list of examples above does not include every targeted therapy. You can learn more about targeted therapy in each cancer-specific section on Cancer.Net in the "Types of Treatment" and "Latest Research" pages. You can also learn more about the latest targeted therapy research on the Cancer.Net blog.

Are there limitations to targeted therapy?

As with any cancer treatment, targeted therapy may not be the best treatment for every person with cancer. It may seem simple to use a drug for your specific cancer, but targeted therapy is complex, and it does not always work. It is important to know that:

  • A targeted treatment will not work if the tumor does not have the target

  • Having the target does not mean the tumor will respond to the drug

  • The response to the treatment may not last over time

For example, the target may not be as important for the cancer’s growth as previously thought, so the drug does not provide much benefit. Or cells may become resistant to the targeted therapy, so the drug might work at first but then stop working.

Also, targeted therapy drugs may cause serious side effects. These are usually not the same as chemotherapy effects. For example, people who get targeted therapy often have skin, hair, nail, or eye problems. It is always important to talk with your doctor about the specific side effects possible for each drug in your treatment plan.

Targeted therapy is an important type of cancer treatment. But, so far, doctors can only treat a few cancers with targeted therapy. Most people with cancer also need surgery, chemotherapy, radiation therapy, or hormone therapy.

Questions to ask your health care team

Talk with your health care team about whether targeted therapy may be part of your treatment plan. If so, consider asking these questions:

  • What type of targeted therapy do you recommend? Why?

  • What are the goals of this treatment?

  • Will targeted therapy be my only treatment? If not, what other treatments will be a part of my treatment plan?

  • How will I receive targeted therapy treatment and how often?

  • What are the possible short-term and long-term side effects of targeted therapy?

  • How will this treatment affect my daily life? Will I be able to work, exercise, and perform my usual activities?

  • What targeted therapy clinical trials are available for me?

  • Whom should I call with questions or problems?

Related Resources

What is Personalized Cancer Medicine?

Introduction to Cancer Research

Understanding Pharmacogenomics

Understanding Immunotherapy

More Information

National Cancer Institute: Targeted Cancer Therapies

My Cancer Genome: Overview of Targeted Therapies for Cancer