What Is Herzuma® (trastuzumab-pkrb)?

Reviewed by: HU Medical Review Board | Last reviewed: June 2023

Herzuma® (trastuzumab-pkrb) is used to treat certain people with metastatic breast cancer that is positive for the human epidermal growth factor receptor 2 (HER2+). It is used for HER2+ metastatic breast cancer:

  • In combination with paclitaxel as a first-line treatment
  • Alone in people who have previously been treated with at least one chemotherapy course for metastatic breast cancer

Metastatic breast cancer is cancer that has spread to other parts of the body, such as the bones or liver. Breast cancer tumors are defined as HER2+ or HER2- cancers. HER2 refers to a specific protein that appears on the surface of cancer cells and can lead to faster growth and spread of the cancer. When cancer cells produce too many HER2 molecules, they are called HER2+ tumors.1,2

Herzuma is also used as adjuvant therapy for certain forms of HER2+ early breast cancer. Adjuvant therapy attempts to keep cancer from coming back after initial treatment, like surgery.1,2

Herzuma is a biosimilar to Herceptin® (trastuzumab). Approved biosimilar drugs have no clinically meaningful differences from their approved reference product.1

What are the ingredients in Herzuma?

The active ingredient in Herzuma is trastuzumab-pkrb.3

How does Herzuma work?

Herzuma is a monoclonal antibody. Antibodies are a normal part of our immune system that act against antigens. These include bacteria, viruses, and other foreign organisms that threaten our health. Monoclonal antibodies used in cancer treatment are created in a lab to attach to specific antigens on the surface of cancer cells.2-5

Certain breast cancer cells have large numbers of HER2 proteins on them. HER2 proteins stimulate tumors to grow especially fast. Herzuma targets these proteins to block the growth and spread of HER2+ breast cancers.2-5

What are the possible side effects?

The most common side effects of Herzuma, depending on the specific form of breast cancer being treated, include:1,3-5

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

Herzuma has a boxed warning, the strictest warning from the U.S. Food and Drug Administration (FDA). This is because it may cause severe side effects, including:3

  • Heart problems, including congestive heart failure
  • Lung damage
  • Infusion-related reactions
  • Birth defects and death in unborn babies

These are not all the possible side effects of Herzuma. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with Herzuma.

Other things to know

Your doctor will monitor your heart function before and during treatment with Herzuma.1,3-5

Herzuma can harm an unborn baby. If you can become pregnant, you should use birth control during treatment and for some time after the last dose of Herzuma. You should also not breastfeed during treatment with Herzuma and for some time after the last dose. Talk to your doctor about your options for birth control and breastfeeding while taking Herzuma.3-5

Before taking Herzuma, tell your doctor if you:5

  • Are allergic to trastuzumab
  • Have or have had heart disease
  • Have or have had lung disease, a tumor in your lungs, or difficulty breathing

Before beginning treatment for breast cancer, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

For more information, read the full prescribing information of Herzuma.

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