The medicineinfo-icon trastuzumab (Herceptin and biosimilars) is the most common medicine used to treat HER2-positive breast cancer. It is a monoclonal antibodyinfo-icon, a medicine made in a lab that attacks a specific proteininfo-icon produced on the outside of a cellinfo-icon. It falls in a class of medicines called targeted therapies.

Research shows people with HER2-positive breast cancer treated with trastuzumabinfo-icon along with chemotherapyinfo-icon are likely to live longer than those with HER2-positive disease who receive chemotherapy alone. Treatment with trastuzumab and chemotherapy also cuts the risk of recurrenceinfo-icon, or return of the cancer, in half.

How trastuzumab works

Trastuzumabinfo-icon works by attaching to HER2 proteins and blocking the signals that tell cells to multiply too quickly, causing cancer.

How trastuzumab is given

Trastuzumabinfo-icon can be given by veininfo-icon or by injectioninfo-icon.

Trastuzumab given by vein uses a needle or a port to drip medicineinfo-icon directly into a vein in a process called infusioninfo-icon. The first infusion may last 90 minutes or longer, after which infusions usually take around 30 minutes. The doseinfo-icon is based on how much you weigh.

Trastuzumab given by injection is delivered by inserting a needle under the skin, usually in the thigh, without needing to access a vein. It takes about 5 minutes. The dose does not change based on your weight. This treatment is called trastuzumab and hyaluronidase-oyst (Herceptininfo-icon Hylecta). 

In early-stageinfo-icon disease, you may receive trastuzumab or trastuzumab and hyaluronidase-oyst either before or after surgeryinfo-icon. The medicine is given either once a week or once every 3 weeks for a year. It is given with chemotherapyinfo-icon at the start of treatment, then may be given alone for an extended period of time. If you have a high risk of recurrenceinfo-icon, you may also receive pertuzumab (Perjeta), another HER2-targeting treatment, either before or after surgery. Pertuzumabinfo-icon can be given with trastuzumab in a single injection called pertuzumab, trastuzumab, and hyaluronidase-zzxf (Phesgo).

Common combinations that include trastuzumab are:

One common plan is to take chemotherapy alone for several cycles, and then take taxane chemotherapy along with trastuzumab. When you finish the taxaneinfo-icon, your team will continue to give you trastuzumab until you finish about a year of treatment. Your providers may also give you all your chemotherapy first and then start trastuzumab. Ask why they suggest one option over the other.

When given before surgery, trastuzumab and medicines given with it help to shrink large tumors. In some cases, this neoadjuvant treatment makes it possible to have a lumpectomyinfo-icon instead of a mastectomyinfo-icon.

In metastaticinfo-icon breast cancer, trastuzumab can be given alone on an ongoing basis or with pertuzumab and chemotherapy. Ask your team to explain why they recommend a certain treatment or combination.

You and your doctor will discuss the best treatments for your situation.

Side effects and things to remember

In general, trastuzumabinfo-icon is less likely than chemotherapyinfo-icon to cause serious side effects that could make you need to stop treatment. Some people have flu-like symptoms after starting trastuzumab. The most common side effects include

If you are also receiving chemotherapy, you may also have chemotherapy side effects.

Heart problems are a rare but serious possible side effectinfo-icon of trastuzumab. The idea of heart issues can be scary, but research shows most heart problems caused by trastuzumab are not permanent or long-term. Though it’s unlikely you’ll have serious heart problems while taking trastuzumab, it’s important your doctor closely monitor your heart health while you take this medicineinfo-icon.

Before you start trastuzumab and throughout treatment, you should get an echocardiogram (sometimes called an echo) to look at your heart health. If your first echo suggests you have heart problems, trastuzumab may not be the right treatment for you. Talk with your healthcare team about other options.

Before starting trastuzumab, tell your doctor about any medicines you are taking, including vitamins, herbal supplements, and over-the-counterinfo-icon medicines. Trastuzumab may be dangerous to a fetus if taken while pregnant. You should not take it if you are pregnant or breastfeeding, and you should take steps to avoid getting pregnant while on trastuzumab.

Your doctor, pharmacistinfo-icon or nurseinfo-icon can help you manage your side effects. You can also go to our section on side effects for more information.

March 25, 2021