Types of targeted therapies used to treat cancer
Many different types of targeted therapies are used to treat cancer, and many more are being developed.
Targeted drugs come in 2 main forms:
- Monoclonal antibody drugs are man-made versions of large immune system proteins (called antibodies) that are designed to attack a very specific target on cancer cells (or other cells). These types of drugs are sometimes referred to as biologics because they are made in living cells. The generic names for these drugs (as opposed to the brand names) all end in -mab; for example, rituximab, panitumumab, etc.
- Small-molecule drugs are chemicals like most other types of drugs. They are not antibodies. Since antibodies are large molecules, these other drugs are sometimes called small-molecule targeted drugs. The generic names for most of these drugs end in -ib; for example, imatinib, dasatinib, etc.
Either of these forms of drugs can be developed to attack a certain target on cancer cells.
Examples of types of targeted drugs
Targeted drugs can be grouped by how they work or what part of a cell they target. A few of the more common types of targeted therapies are listed here, but this is not a complete list. Many different targeted drugs are being used, and new ones are coming out all the time.
Signal transduction inhibitors
The cells in our bodies normally grow (or stop growing) in response to chemical signals they pick up from the area around them. These signals are transmitted through proteins to the cell’s control center, telling it what to do. In cancer cells, these signals sometimes get stuck in the “on” position, telling the cell to grow even without it getting an outside signal.
Some targeted drugs block (inhibit) proteins that are signals for cancer cells to grow. Blocking these cell signals can sometimes help keep the cancer under control, although it’s not clear if any of these drugs alone can cure cancers. Some of these drugs are used by themselves, while others are used along with other treatments, such as chemo.
Examples of signal transduction inhibitors include:
- EGFR inhibitors, such as cetuximab (Erbitux) and erlotinib (Tarceva), which are used to treat some lung, colorectal, and other cancers
- HER2 inhibitors, such as trastuzumab (Herceptin) and pertuzumab (Perjeta), which are used to treat some breast, stomach, and other cancers
- BCR-ABL inhibitors, such as imatinib (Gleevec) and dasatinib (Sprycel), which are used to treat chronic myelogenous leukemia (CML) and some other cancers
- ALK inhibitors, such as crizotinib (Xalkori) and ceritinib (Zykadia), which are used to treat some lung cancers
- BRAF inhibitors, such as vemurafenib (Zelboraf) and dabrafenib (Tafinlar), which are used to treat some melanomas
Angiogenesis is the process of making new blood vessels. This is usually a normal, healthy process, because as the body grows and develops, it needs to make new blood vessels to get blood to all of its cells. Even as adults, there are times when angiogenesis is important. For instance, new blood vessels help the body heal wounds and repair damage.
But this same process can help tumors grow by giving them their own blood supply. This blood brings nutrients that can allow the cancer to grow and spread.
Drugs called angiogenesis inhibitors stop tumors from making new blood vessels, which greatly limits how big they can grow. Many of these drugs work by blocking vascular endothelial growth factor (VEGF) proteins or the VEGF receptors on cells that these proteins attach to. These proteins normally help new blood vessels to form around tumors.
Some angiogenesis inhibitors only block new blood vessel growth, while others can affect other targets in cancer cells as well.
Examples of angiogenesis inhibitors include bevacizumab (Avastin) and ramucirumab (Cyramza).
Some targeted therapies change the proteins within the cancer cells that cause the cells to die. These are called apoptosis-inducing drugs. Apoptosis is another word for cell death.
Examples include drugs called proteasome inhibitors, such as bortezomib (Velcade) and carfilzomib (Kyprolis). A proteasome is a complex of enzymes inside a cell that helps destroy proteins that the cell no longer needs. Sometimes in cancer cells, the proteasomes break down proteins that normally would cause the cell to die. This allows the cell to keep living. These drugs stop the proteasomes from breaking down these proteins, which in turn makes the cancer cell die.
The immune system helps protect the body from infections. The immune system can also help protect against cancer to some extent, but it doesn’t do this quite as well.
Some drugs help boost the immune system’s ability to fight cancer. Some of these drugs act in a very general way, but others can be considered to be a type of targeted therapy. An example would be drugs called immune checkpoint inhibitors.
An important part of the immune system is its ability to keep itself from attacking other normal cells in the body. To do this, it uses “checkpoints” – proteins on immune cells that need to be turned on (or turned off) to start an immune response. Cancer cells sometimes find ways to use these checkpoints to avoid being attacked by the immune system. But newer drugs that target these checkpoints hold a lot of promise as cancer treatments. Examples include drugs that target the PD-1 and PDL-1 proteins, such as pembrolizumab (Keytruda), and drugs that target CTLA-4 protein, such as ipilimumab (Yervoy).
Some other immunotherapy drugs could be considered targeted drugs as well. To learn more about the use of immunotherapy drugs to treat cancer, see our document Cancer Immunotherapy.
Monoclonal antibodies attached to toxins
As noted earlier, monoclonal antibodies can be created to attach to very specific targets on cancer cells. Researchers have learned how to attach small amounts of a chemical toxin or radioactive substance to some of these antibodies. Once inside the body, the antibody acts as a homing device to take the toxic substance directly to the cancer cells, but not to other cells in the body. This limits the damage to normal cells.
Examples of these types of antibodies include brentuximab vedotin (Adcetris) and ado-trastuzumab emtansine (Kadcyla).Getting targeted therapy for cancer
Who can get targeted therapy?
Not every type of cancer is helped by targeted therapy. Cancer cells are sometimes tested to see if they contain the target – usually a specific protein, gene, or enzyme –that the drug can hit.
Targeted drugs are now used to treat many types of cancer. But these drugs are not always an option (or in some cases they might not be the best option).
For some types of cancer, most people will have the target on their cancer cells that a particular targeted drug affects. For example, in most people with chronic myelogenous leukemia (CML), the cancer cells have the abnormal BCR-ABL gene that certain drugs target very effectively.
But for other cancer types, a person’s tumor tissue needs to be tested first to find out if the cancer cells have the right target. The use of a targeted drug might be restricted to people whose tumors have this target, because the drug wouldn’t help people whose tumors don’t have the target. For example, only a small portion of people with lung cancer have an abnormal ALK gene in their cancer cells. Targeted drugs called ALK inhibitors are only useful in people whose tumors have this abnormal gene.
There might be other factors to consider. For example, sometimes targeted therapies have only been shown to help patients who meet certain criteria (for example, their cancer didn’t respond or is no longer responding to other treatments).
How are targeted drugs given?
The most common ways to give these drugs are by mouth (as a pill or capsule) or into a vein (intravenous or IV). A few targeted drugs might injected under the skin (subcutaneously, or SubQ).
When the drug is taken by mouth you can take the pills or capsules at home. If you take a targeted drug by mouth, it’s very important to take the exact dose, at the right time, for as long as it has been prescribed. For some cancers, targeted drugs are taken by mouth for many years.
IV drugs are usually given as an infusion that can last 30 minutes to a few hours. A mixed drug solution flows from a plastic bag through an IV line into one of your veins. The flow is often controlled by a machine called an IV pump. The infusion might be done in your doctor’s office, in a clinic, in a hospital’s outpatient department, or even at home. Talk to your doctor or nurse ahead of time so that you know what to expect during treatment.
To learn more about a particular targeted drug and how it’s given, call us at 1-800-227-2345. For more general information on medicines that are taken by mouth to treat cancer, see our document Oral Chemotherapy: What You Need to Know.
How often will I need to get treatment and how long will it last?
How often you get the targeted drug and how long your treatment lasts depend on the kind of cancer you have, the goals of the treatment, the drugs being used, and how your body responds to them. You may get treatments daily, weekly, every few weeks, or even less often. Some drugs are given in on-and-off cycles. The breaks allow your body to build healthy new cells and regain its strength. Other drugs are OK to take every day for many months or even years.
Does targeted therapy hurt?
Many targeted drugs are taken as pills, but some are given into a vein (IV) or under the skin (SubQ). Getting an IV or SubQ targeted drug should not hurt beyond the discomfort of the needlestick. If you notice pain, burning, coolness, swelling, or anything unusual while you are getting the medicine, tell your doctor or nurse right away.
Can I take other medicines while I’m getting targeted therapy?
Many medicines and supplements are probably safe to take while you’re getting targeted therapy. But some might make your treatment less effective, or might even make its side effects worse. Likewise, some targeted drugs might affect other medicines you are taking.
To be sure that your treatment works as well as it can, first gather up everything you’re taking so you can tell your doctor or nurse about it.
- Make a list of the name of each prescription and non-prescription medicine, vitamin, mineral, herb, or supplement, the dose, how often you take it, the reason you take it, and who prescribed it (if applicable).
- Be sure to include the things you might not think of as medicines, even those you take every now and then. This includes aspirin or other pain relievers, and all over-the-counter medicines and supplements. Don’t forget those you take for fever or aches and pains, drugs for heartburn and other stomach problems, cold and flu remedies, sleeping medicines, drugs for allergy symptoms, and other “as needed” drugs.
Your doctor will tell you if you should stop taking any of these medicines before you start treatment. After treatment starts, check with your doctor before taking any new medicines or supplements and before stopping the ones you already take.
Last Medical Review: 12/08/2014
Last Revised: 12/11/2014