The medicine trastuzumab (Herceptin and biosimilars) is the most common medicine used to treat HER2-positive breast cancer. It is a monoclonal antibody, a medicine made in a lab that attacks a specific protein produced on the outside of a cell. It falls in a class of medicines called targeted therapies.
Research shows people with HER2-positive breast cancer treated with trastuzumab along with chemotherapy 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 recurrence, or return of the cancer, in half.
If the cancer you have is both hormone receptor positive and HER2 positive, you are likely to receive targeted treatments for both types of breast cancer.
Trastuzumab given by vein uses a needle or a port to drip medicine directly into a vein in a process called infusion. The first infusion may last 90 minutes or longer, after which infusions usually take around 30 minutes. The dose 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 (Herceptin Hylecta).
In early-stage disease, you may receive trastuzumab or trastuzumab and hyaluronidase-oyst either before or after surgery. The medicine is given either once a week or once every 3 weeks for a year. It is given with chemotherapy at the start of treatment, then may be given alone for an extended period of time. If you have a high risk of recurrence, you may also receive pertuzumab (Perjeta), another HER2-targeting treatment, either before or after surgery. Pertuzumab can be given with trastuzumab in a single injection called pertuzumab, trastuzumab, and hyaluronidase-zzxf (Phesgo).
Common combinations that include trastuzumab are:
- ACTH (Adriamycin, Cyclophosphamide, Taxol and Herceptin)
- TCH (Taxotere or Taxol, Cyclophosphamide and Herceptin)
- THP (Taxotere, Herceptin and Perjeta)
One common plan is to take chemotherapy alone for several cycles, and then take taxane chemotherapy along with trastuzumab. When you finish the taxane, 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 lumpectomy instead of a mastectomy.
In metastatic 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.
In general, trastuzumab is less likely than chemotherapy 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
- fever or chills
- muscle aches
- skin reaction to injection, including redness and irritation
- Low white blood cell count, which can lead to infections
If you are also receiving chemotherapy, you may also have chemotherapy side effects.
Heart problems are a rare but serious possible side effect 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 medicine.
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-counter 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.