What is targeted therapy?
Targeted therapy is a form of cancer treatment that precisely targets cancer cells, destroying them or preventing them from growing and dividing. Targeted therapies can identify and attack abnormal cells based on proteins or DNA changes specific to the cancer cells while minimizing the impact on your healthy cells.
Targeted therapy for cancer is considered precision medicine or precision oncology, as it is a personalized approach tailored to findings in your cancer. It differs from traditional or standard chemotherapy, which kills both healthy cells and cancer cells. However, it is often combined with other treatments, including conventional chemotherapy, radiation therapy and surgery.
Types of targeted therapy
Many targeted therapies exist, and they can treat many kinds of cancer. However, targeted therapies often fall into two main categories: small-molecule drugs, which are tiny enough to enter a cancer cell, and large-molecule drugs, which work by attacking the proteins or enzymes on the cell’s surface.
Your doctor will determine which targeted therapy may be best for you after ordering lab tests and, possibly, a biopsy, which involves taking a sample of your tumor so it can be tested. The results of these tests help your team learn about your cancer and determine a personalized treatment plan for you.
Angiogenesis inhibitors
Angiogenesis is the formation of new blood vessels. It plays a key role in tumor growth since tumors require a healthy blood supply to grow larger. Angiogenesis inhibitors are targeted drugs that stop the formation of new blood vessels. They bind to proteins and other substances involved in blood vessel formation, stopping or slowing tumor growth.
Because angiogenesis inhibitors do not kill cancer cells, you may have to take them over a long period or in combination with other treatments.
Monoclonal antibodies
Antibody receptors, or antibodies, are proteins your immune system makes to attack viruses, other foreign substances or unhealthy cells in your body, also known as antigens. Monoclonal antibodies are drugs made in a laboratory that mimic natural antibodies and help you fight off illness.
Some monoclonal antibodies are a form of targeted therapy, as they are designed to identify and attack a specific target on cancer cells, stopping them from growing and spreading. Other monoclonal antibodies can be seen as a type of immunotherapy, as they stimulate your immune system to fight the cancer.
Signal transduction inhibitors
Signal transduction inhibitors are drugs that block the signals passed between molecules in a cell. The drugs can enter a cancer cell or identify substances on its surface, interrupting its normal functioning. As a result, the cancer cells die or stop dividing.Hormone therapies
Hormones are chemical messengers produced by our bodies, but some types of breast, uterine (endometrial), ovarian and prostate cancer also need hormones to grow. Hormone therapies work either by stopping your body from producing certain hormones or by interfering with the effects of the hormones on cancer cells. They can make cancer less likely to return after surgery.
Your doctor might test a sample of tissue to see if your cancer is hormone-sensitive and likely to respond to hormone therapy. Prostate cancers need the male sex hormone androgen in their early stages to grow. Around 80% of breast cancers are hormone sensitive.
What kinds of cancer does targeted therapy treat?
The Food and Drug Administration has approved targeted drug therapies to treat more than 30 different forms of cancer. Some drugs have been approved to treat more than one kind of cancer. Since targeted therapy is an individualized approach, your doctor will tailor your treatment to your specific type of cancer.
Common cancers treated with targeted therapy include:
How does targeted therapy work?
Targeted therapies can distinguish cancer cells from normal cells by detecting specific proteins, too much of a particular protein or changes in a cell’s DNA. The drugs then stop the cancer cells from functioning normally in various ways.
These include blocking the chemical signals that cause them to grow, changing their proteins, carrying toxins to make them die, or stopping them from making blood vessels or responding to hormones that cause them to grow. Targeted therapies can also trigger your immune system to attack the cancer cells.
When is targeted therapy used?
Your doctor may recommend targeted therapy based on the results of biomarker testing.
Each person’s cancer has unique biomarkers, which are genes, proteins or other substances that provide information about the cancer. Your cancer’s biomarkers can affect how you respond to treatment and whether targeted therapies are appropriate. Biomarker testing can help your doctor determine if your cancer has targets that can be effectively treated with a drug.
Cancer cells can become resistant to targeted therapy and find new ways to grow. Often, doctors combine targeted therapies with other treatments, such as radiation therapy, but some cancers can be treated using only targeted therapy.
What to expect
If you and your care team decide to move forward with targeted therapy, they will explain what to expect when it comes to treatment results, benefits and risks, and possible side effects.
How often you receive treatment will depend on your cancer type, the targeted therapy you receive and how your body responds to treatment. Targeted therapies are typically given in cycles—you might get treatment daily, weekly or monthly, with rest periods in between to allow your body to recover.
Since targeted therapies are relatively new, your team may recommend safety precautions to protect themselves, your family and your friends from exposure. Your care team will probably wear protective clothing during treatment. You can ask a friend or relative to accompany you to your appointment, but they might be asked to remain in a waiting room.
Before treatment
Your doctor will order tests to determine whether your cancer is likely to respond to targeted therapy and, if so, which drugs to use. Tests may include genomic testing, which looks at the genome (or genetic material) inside your cancer cells.
Your test results can show the changes that make the cancer cells different from normal cells. They can indicate how quickly a tumor is likely to grow and which treatments will be most effective.
Your care team will also help you navigate other needs. For example, targeted therapy drugs that interfere with blood vessel formation can affect blood clotting and wound healing, so you may need to postpone other planned surgeries, including dental procedures, or stop taking certain medications before treatment begins.
During treatment
Targeted therapies are usually given either by mouth or directly into your vein (intravenously, or IV). During IV treatment, a needle will be used to put a tiny tube called a catheter in your arm. The drugs can be injected through the catheter, which takes just a few minutes, or given as an infusion, which can last up to a few hours.
Some drugs can be taken in pill, capsule or liquid form at home. Your doctor will tell you exactly when and how much to take and how to handle your medicine safely. Tell them immediately if you forget to take a dose or feel too sick to take your medicine.
After treatment
If you receive treatment at a hospital or outpatient center, ask if you need someone to drive you home afterward.
You might have side effects immediately after an infusion. These are sometimes called infusion reactions and include discomfort, swelling or redness at the needle site and flu-like symptoms. Tell your healthcare team right away about any symptoms.
You will visit your doctor regularly to see how well your treatment is working and they will monitor you for side effects. You will have physical exams and medical tests, such as blood tests, X-rays and other scans. Your doctor might also check your heart and blood pressure during and after treatment.
Possible side effects of targeted therapy
Like other types of cancer treatment, targeted therapies can cause side effects. These often depend on the type of drug used. They can also vary from one person to another. Some people have severe side effects, while others have mild or even no side effects.
Most side effects will go away soon after treatment ends. They could include:
- Allergic reactions (when receiving IV medications)
- Chronic or nonhealing wounds
- Coughing
- Diarrhea or constipation
- Fatigue
- Hair or skin color changes
- Heart damage
- High blood pressure
- Liver problems
- Mouth sores
- Nail changes
- Nausea or vomiting
- Numbness or tingling in hands and feet
- Problems with blood clotting
- Shortness of breath or difficulty breathing
- Skin problems, such as dry skin, rashes or sensitivity to light
- Swelling in your face, hands, feet or legs
Some drugs have also been linked to damage to organs, such as the thyroid gland or kidneys, and increased risk of other infections or a second cancer.
Most symptoms will improve as your healthy cells recover. However, targeted therapies are relatively new, so more research is needed into long-term side effects.