What is Herceptin® ? (trastuzumab)

Herceptin is a targeted treatment used to treat breast cancer that is positive for the human epidermal growth factor receptor 2 (HER2+). It may be used in combination with chemotherapy drugs, or it may be used alone in women who have already received chemotherapy. Trastuzumab is manufactured by Genentech.

What is the active ingredient in Herceptin?

The active ingredient in Herceptin is trastuzumab, a monoclonal antibody which blocks the HER2 receptor.1

How does trastuzumab work?

Trastuzumab is a monoclonal antibody. Antibodies are a normal part of the immune system that attach to antigens (such as germs) to mark them for destruction by other components in the immune system. Monoclonal antibodies are created in a laboratory to attach to specific antigens on the surface of cancer cells. Trastuzumab attaches to the HER2 receptor.

Breast cancers that are classified as HER2+ have an excess of HER2 receptors, which can cause the cancer to grow and spread quickly. Trastuzumab targets these receptors and has been shown to block the growth and spread of HER2+ breast cancers.1,2

What are some of the possible side effects of trastuzumab?

Trastuzumab may cause serious side effects, including1,2:

  • Heart problems, such as congestive heart failure or reduced heart function
  • Infusion reactions, which may cause fever, chills, nausea, vomiting, pain, headache, dizziness, and/or shortness of breath
  • Serious harm to an unborn baby, which may cause serious birth defects or death

The most common side effects experienced by women with metastatic breast cancer receiving trastuzumab include1:

  • Fever
  • Chills
  • Headache
  • Congestive heart failure
  • Insomnia
  • Cough
  • Rash
  • Infection

Patients should talk to their doctor about these or any other potential side effects they experience while receiving trastuzumab.

Things to know about trastuzumab

Because trastuzumab can cause birth defects or fatal harm to an unborn fetus, women who can become pregnant who receive trastuzumab should use birth control during their treatment and for 7 months after treatment with trastuzumab is completed (patients should discuss appropriate birth control methods with their doctor).1,2

Because trastuzumab may cause heart damage, heart function tests may be performed before and during treatment with trastuzumab. Based on the results of these tests, your treatment with trastuzumab may be paused or stopped.1,2

Chemotherapy can cause lowered white blood cell counts. When given in combination with chemotherapy, trastuzumab may potentially worsen this effect.1

Receiving trastuzumab

Trastuzumab is given as an intravenous (IV) infusion, and the infusion usually takes between 30 and 90 minutes. Other additional treatments, such as chemotherapy, will take additional time for infusion administration when given in combination with trastuzumab infusion.

Herceptin Hylecta (trastuzumab and hyaluronidase-oysk), a newer formulation of trastuzumab is also approved by the U.S. Food & Drug Administration. Herceptin Hylecta™ includes the same monoclonal antibody as intravenous trastuzumab in combination with recombinant human hyaluronidase PH20, an enzyme that helps to deliver trastuzumab subcutaneously (which means delivered under the skin). Herceptin Hylecta is a ready-to-use formulation that can be administered much more quickly than intravenous trastuzumab, reducing administration time to 2 to 5 minutes, compared to 30 to 90 minutes for the intravenous formulation.3,4

These are not all the possible side effects of trastuzumab. Patients should talk to their doctor about what to expect with treatment with trastuzumab. Before starting treatment with trastuzumab, patients should tell their doctor or healthcare provider about all their medications (prescription and over-the-counter), herbal supplements, and vitamins they are taking.

Patients should talk to their doctor if they have any questions, or if they have questions regarding their trastuzumab regimen.

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Written by: Editorial Team | Last reviewed: October 2020.