Anti-HER2 therapies (also called HER2 inhibitors or HER2-targeted therapies) are a class of medicines used to treat all stages of HER2-positive breast cancer, from early-stage to metastatic. Metastatic breast cancer is cancer that has spread to other parts of the body away from the breast, such as the bones or liver.
In HER2-positive breast cancer, the HER2 (human epidermal growth factor receptor 2) gene doesn’t work correctly and makes too many copies of itself. These extra HER2 genes make too many proteins known as HER2 receptors. These HER2 receptors are like ears, or antennae, on the surface of the breast cells. The HER2 receptors receive signals that stimulate the cell to grow and multiply. But breast cancer cells with too many HER2 receptors can pick up too many growth signals. This makes breast cells grow and divide too fast in an uncontrolled way.
How anti-HER2 therapies work
Anti-HER2 medicines attach to the HER2 receptor proteins on the surface of breast cancer cells. Because anti-HER2 medicines specifically target HER2 receptors, you may hear them referred to as “HER2-targeted therapies.” There are also other types of targeted therapies that target different receptors.
Anti-HER2 medicines work by blocking the HER2 receptors from receiving the growth signals in HER2-positive breast cancer. By blocking the growth signals, anti-HER2 medicines can slow or stop the growth of HER2-positive breast cancer. Anti-HER2 medicines only work on HER2-positive breast cancer. They do not work on HER2-negative breast cancer.
Choosing an anti-HER2 therapy: Which one is right for you?
There are many different medicines that are used to treat HER2-positive breast cancer by targeting HER2 receptors. Many HER2 inhibitors are given in combination with other treatments. Some anti-HER2 medicines called “antibody-drug conjugates” are made with HER2 inhibitors and have other medicines attached to them.
Some of these anti-HER2 medicines also carry chemotherapy directly to the HER2-positive cancer cells, which helps protect healthy cells from the toxic effects of chemotherapy medicines.
You and your doctor will decide which anti-HER2 treatment is right for you based on factors such as:
- the stage and size of the cancer
- any earlier treatments you have had
- if the cancer grew after any previous treatment
- the side effects associated with each anti-HER2 treatment
- whether your health insurance favors one of the medications over the others
Women who are pregnant, plan on becoming pregnant, or are breastfeeding should not get targeted therapies. The little research that has been done suggests that targeted therapies are not safe during pregnancy. Read more about Treatment for Breast Cancer During Pregnancy.
Here are some different types of medicines that target HER2 receptors.
Monoclonal antibodies are made in a lab and work like the antibodies made naturally by our immune systems. In addition to targeting HER2 receptors on breast cancer cells, these medicines can also help fight breast cancer by alerting the immune system to destroy cancer cells. Because of this, they are sometimes called “immune targeted therapies.”
Almost all of these treatments are given by intravenous infusion, which means it is delivered directly into your bloodstream through an IV or a port.
Herceptin (chemical name: trastuzumab) is used to treat both early-stage and advanced HER2-positive breast cancer and can be given with chemotherapy and sometimes another targeted therapy called Perjeta (chemical name: pertuzumab). Learn more about Herceptin.
Herceptin Hylecta is a different form of Herceptin that is used to treat the same people with HER2-positive breast cancer but is given as an injection under the skin. Learn more about Herceptin Hylecta.
The medicines Herzuma, Kanjinti, Ogivri, Ontruzant, and Trazimera are biosimilars to Herceptin. Biosimilars are almost identical to a type of medicine called a biologic that is already approved by the U.S. Food and Drug Administration (or similar organizations in other countries). Biologics — including monoclonal antibodies, such as Herceptin — are medicines that are made from or contain parts of living cells. It can help to think of a biosimilar as a generic version of a biologic drug, though that comparison isn’t completely accurate. Learn more about Herceptin biosimilars.
- Margenza (chemical name: margetuximab-cmkb) is used in combination with chemotherapy to treat people diagnosed with metastatic HER2-positive breast cancer who have been treated previously with two or more anti-HER2 regimens. Learn more about Margenza.
- Perjeta (chemical name: pertuzumab) is used in combination with Herceptin and chemotherapy medicines to treat HER2-positive, metastatic breast cancer that hasn’t been treated with either Herceptin or chemotherapy yet. Learn more about Perjeta.
Antibody-drug conjugates are made with HER2 inhibitors and other medicines attached (conjugated) to them. There are three antibody-drug conjugates that include trastuzumab, the chemical ingredient in Herceptin.
- Enhertu (chemical name: am-trastuzumab-deruxtecan-nxki) can be used to treat people diagnosed with metastatic HER2-positive breast cancer that has been previously treated with at least two other anti-HER2 medicines. Enhertu also can be used to treat HER2-positive breast cancer that can’t be removed with surgery. Learn more about Enhertu.
Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine) can be used to treat people diagnosed with HER2-positive metastatic breast cancer that has previously been treated with Herceptin and taxane chemotherapy.
Kadcyla also can be used after surgery in people diagnosed with early-stage HER2-positive breast cancer that was treated with Herceptin and taxane chemotherapy before surgery and had residual disease found during surgery. Learn more about Kadcyla.
- Phesgo (chemical name: pertuzumab, trastuzumab, and hyaluronidase-zzxf) can be used in combination with chemotherapy before surgery for early-stage or inflammatory HER2-positive breast cancer. Phesgo also can be used after surgery for early-stage HER2-positive breast cancer that has a high risk of recurrence. Learn more about Phesgo.
Enhertu and Kadcyla are given by intravenous infusion, which means it is delivered directly into your bloodstream through an IV or a port. Phesgo is given as an injection under the skin in the thigh. When a medicine is injected under the skin, it’s called a subcutaneous injection.
- Nerlynx (chemical name: neratinib) is used to treat early-stage HER2-positive breast cancer for an extended period of time after surgery and chemotherapy. Nerlynx also is used in combination with chemotherapy to treat advanced-stage and metastatic HER2-positive breast cancer. Nerlynx is a pill taken by mouth. Learn more about Nerlynx.
Signal transduction inhibitor
- Tykerb (chemical name: lapatinib) advanced or metastatic breast cancer that is HER2-positive in combination with chemotherapy medicines. Tykerb is a pill taken by mouth. Learn more about Tykerb.
Tyrosine kinase inhibitor
Tukysa (chemical name: tucatinib) is used to treat metastatic or locally advanced HER2-positive breast cancer that can’t be completely removed with surgery, after the cancer has been treated with at least one anti-HER2 medicine. Locally advanced breast cancer is breast cancer that has spread to tissue near the breast, but not to parts of the body away from the breast. Metastatic breast cancer is breast cancer that has spread to parts of the body away from the breast, such as the bones or liver.
Tukysa is a pill taken by mouth and is used in combination with other medicines. Learn more about Tukysa.
Side effects of anti-HER2 therapies
Like almost all cancer medicines, anti-HER2 medicines can cause side effects. Some of the most common ones are
If you are receiving HER2 inhibitors which are combined with chemotherapy medicines, you may also experience chemotherapy side effects.
Some anti-HER2 medicines can cause serious side effects. For example Herceptin, Phesgo and others can cause serious heart problems. Some drugs may cause serious lung problems, which can be life-threatening. HER2 inhibitors that are combined with chemotherapy medicines can cause chemotherapy side effects that are less common, but more serious:
Written by: Sue Nichols, contributing writer
Reviewed by: Brian Wojciechowski, MD, medical adviser
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