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What is Herzuma (trastuzumab-pkrb)?

Herzuma (trastuzumab-pkrb) is an engineered biologic medication that is “biosimilar” to Herceptin. Biosimilar medications are approved based on the similarity of their action to approved medications.

Herzuma was recently approved for use in patients with HER2+ breast cancer, to be used either alone or in combination with other medicines. HER2+ breast cancer is characterized by tumors that overproduce a specific molecule known as human epidermal growth factor receptor-2, or HER2.

Herzuma can be used against metastatic breast cancer or as adjuvant therapy after initial breast cancer treatment.1 Metastatic breast cancer refers to advanced breast cancer that has already spread to other parts of the body. Adjuvant therapy keeps cancer from recurring after initial treatment, like surgery.2 Herzuma is not available in generic forms.

What are the ingredients in Herzuma?

The active ingredient in Herzuma is trastuzumab-pkrb.3

How does Herzuma work?

Herzuma is one of several monoclonal antibodies used to treat breast cancer. Our bodies naturally produce antibodies, which are immune factors that act against bacteria, viruses, and other foreign organisms that invade and pose a threat to our health. Drugmakers have engineered a variety of antibodies to target the mechanisms that cause certain diseases, including metastatic breast cancer.4

Certain breast cancer cells have large numbers of molecules called human epidermal growth factor receptor-2, or HER2, on their cell surfaces. These molecules stimulate abnormally fast cell growth. Like Herceptin, Herzuma binds to and blocks these molecules, also killing the cancerous cells that carry them.

What are the possible side effects of Herzuma?

Common side effects with Herzuma include1:

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

In some patients, Herzuma can cause more harmful side effects. These include worsening of chemotherapy-induced reductions in white blood cells, serious heart problems, life-threatening reactions to infusion, and severe lung damage.5

Herzuma has been shown to harm fetuses, so it is important not to become pregnant or breastfeed while taking Herzuma. Herzuma has not been tested or approved in children.5

This is not an exhaustive list of all potential side effects of Herzuma. For more information, consult your doctor or healthcare provider. If you notice any new or worsening side effects, contact your doctor or healthcare provider immediately.

Things to note about Herzuma

Before taking Herzuma, tell your doctor if you5:

  • Are allergic to trastuzumab or mouse proteins
  • Have or have had heart disease
  • Are being treated with radiation therapy to the chest or with other chemotherapy medicines, since some medications don’t mix well with Herzuma
  • Have or have had lung disease, a tumor in your lungs, or difficulty breathing
  • Are pregnant or plan to become pregnant or are breastfeeding

Tell your doctor about any medications or supplements you are taking while on Herzuma, because it doesn’t mix well with certain medicines. It is important for doctors to test your heart function before and regularly during therapy with Herzuma since it can cause serious heart problems.5

Dosing information

Herzuma is given through a vein in your arm via intravenous infusion. It must be administered by a healthcare provider at a medical office. The first infusion is given over 90 minutes, to be sure you are tolerating the medication well. After that, it can be given over 30 minutes.3

For metastatic breast cancer, the initial dose of Herzuma is 4 mg/kg over 90 minutes, followed by weekly doses of 2 mg/kg over 30 minutes.3

When used as adjuvant therapy, Herzuma is given initially as a 4 mg/kg dose infused over 90 minutes followed by 12 or 18 weekly doses of 2 mg/kg given over 30 minutes. A week later, the medication is given as a 6 mg/kg infusion over 30-90 minutes every 3 weeks, for a total of 52 weeks of therapy. When used as adjuvant therapy, Herzuma is generally given in conjunction with other chemotherapy medications.3

For more information about Herzuma, read the complete prescribing information.

Written by: Emily Downward | Last reviewed: October 2019.
  1. FDA approves Herzuma as a biosimilar to Herceptin. U.S. Food and Drug Administration. Updated December 18, 2018. Available at: Accessed January 21, 2019.
  2. Adjuvant therapy: Treatment to keep cancer from returning. Mayo Clinic. Updated November 3, 2018. Available at: Accessed January 21, 2019.
  3. Prescribing Information. Celltrion, Inc. Yeonsu-gu, Incheon 22014, Republic of Korea. Revised December 2018. Available at: Accessed January 21, 2019.
  4. Package leaflet: Information for the user. Celltrion Healthcare Hungary Kft.. Updated November 2018. Available at: Accessed January 21, 2019.
  5. Trastuzumab Injection. MedLine Plus. US National Library of Medicine. Updated December 15, 2018. Available at: Accessed January 21, 2019.