What Is Margenza® (margetuximab-cmkb)?

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

Margenza® (margetuximab-cmkb) is approved to be used together with chemotherapy to treat adults with metastatic HER2-positive breast cancer who have previously been treated with at least 2 other therapies that target HER2 receptors, with at least 1 of these therapies having been used to treat metastatic breast cancer.1,2

Metastatic cancer happens when cancer has spread from the part of the body where it started to another part or parts of the body. Margenza, made by the drug company MacroGenics, is an Fc-engineered monoclonal antibody that targets the HER2 oncoprotein.1,2

What is the active ingredient in Margenza?

The active ingredient in Margenza is margetuximab-cmkb.3

How does Margenza work?

Margenza targets the HER2 protein, helping to decrease the growth and spread of cancer cells. HER2 stands for human epidermal growth factor receptor 2. HER2 is a gene that makes the HER2 protein located on the surface of breast cells. It helps with the normal growth of these cells.1,3,4

Some cancers, especially breast cancer, can result when the HER2 gene changes and makes extra copies of the gene. This causes an increase in the amount of HER2 protein made, which leads to abnormal growth of cells. Cancers with a high level of HER2 protein are considered HER2-positive.4

Antibodies are proteins made by the immune system to fight infection or disease. Typically, 1 part of the antibody recognizes the harmful substance, while the other part of the antibody (known as Fc) interacts with the immune system to fight the infection or disease. Fc-engineering helps maximize the functions of these antibodies, making them useful as medicines and treatments.5-7

What are the possible side effects?

The most common side effects of Margenza plus chemotherapy include:3

  • Fatigue
  • Nausea and vomiting
  • Diarrhea or constipation
  • Headache
  • Hair loss (alopecia)
  • Abdominal pain
  • Peripheral neuropathy
  • Cough
  • Decreased appetite
  • Muscle, joint, and/or arm/leg pain
  • Fever
  • Shortness of breath
  • Tenderness, redness, and/or pain on the bottom of the feet and/or palms of the hands

Margenza may also cause infusion-related reactions (IRRs). Symptoms may include:3

  • Fevers, chills, body aches
  • Cough
  • Dizziness
  • Fatigue
  • Nausea, vomiting
  • Low blood pressure

Margenza has a boxed warning, the strictest warning from the US Food and Drug Administration (FDA). Is has this warning because of its potential to cause left ventricular dysfunction (part of your heart not functioning well) and toxicity to unborn babies. Reductions in left ventricular ejection fraction (LVEF) can be a potential sign of heart failure. Your doctor will need to monitor your heart function before and throughout treatment.1,3

Margenza 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 Margenza. You should also not breastfeed during treatment with Margenza and for some time after the last dose. Talk to your doctor about your options for birth control and breastfeeding while taking Margenza.3

These are not all the possible side effects of Margenza. Talk to your doctor about what to expect when taking Margenza. You also should call your doctor if you have any changes that concern you when taking Margenza.

Other things to know

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 Margenza.

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