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HER2/NEU RECEPTOR ANTAGONIST
Margenza (margetuximab-cmkb) is a prescription medication approved by the U.S. Food and Drug Administration (FDA) to treat adults with metastatic HER2-positive breast cancer.
Margenza is a monoclonal antibody. This is a type of medicine that can attach to a target on cells. Margenza attaches to human epidermal growth factor receptor 2 (HER2), a protein found on some breast cancer cells.
Margenza may help slow cancer growth. It can help stop HER2-positive tumor cells from growing. It can also help the body’s immune system attack these cells.
Doctors prescribe Margenza when adults with metastatic HER2-positive breast cancer need treatment with chemotherapy after receiving two or more anti-HER2 treatments. At least one of those treatments must have been for cancer that had spread.
Margenza is given as an intravenous (IV) infusion, usually once every three weeks in a 21-day cycle. It is used with chemotherapy, and treatment usually continues until the cancer gets worse or side effects become unacceptable or intolerable.
The recommended dose of Margenza for breast cancer is 15 milligrams per kilogram, given by IV infusion every three weeks.
Doctors may pause treatment, delay the next dose, slow the infusion, or stop treatment if side effects are serious or too hard to manage.
This information is based on the prescribing information, but your healthcare provider may tailor your treatment plan. Always follow their guidance.
In clinical trials of Margenza used with chemotherapy for adults with metastatic HER2-positive breast cancer, the most common side effects were reported in more than 10 percent of people taking Margenza with chemotherapy.
These side effects include:
Margenza can cause serious side effects. Some may need medical care right away. These include:
Contact a healthcare professional right away if you have new or worsening shortness of breath, cough, swelling in your ankles, legs, or face, a fast or pounding heartbeat, weight gain of more than 5 pounds in 24 hours, dizziness, or fainting.
TerSera Therapeutics, the manufacturer of Margenza, offers TerSera SupportSource for Margenza. The website describes a Margenza Co-Pay Assistance Program for eligible people with commercial insurance.
TerSera SupportSource for Margenza also offers help enrolling in TerSera SupportSource for Margenza, answers to questions about the Co-pay Assistance and Patient Assistance Programs, eligibility guideline reviews for the Co-pay Assistance and Patient Assistance Programs, and help finding assistance from foundations and charities if you do not have insurance or are not eligible for the Co-pay Assistance and Patient Assistance Programs.
The Margenza Co-pay Assistance Program is not available to people who participate in state or federal healthcare programs, including Medicare, Medicaid, Veterans Affairs, Department of Defense, TRICARE, or similar programs. To learn more, visit the Margenza resources and support page or call 833-377-HER2 (4372).
Before starting Margenza, your doctor will check how well your heart pumps blood. This is called heart function. Your doctor will also check your heart function during treatment.
If you can become pregnant, your doctor should check your pregnancy status before you start Margenza.
Tell your doctor about all medications you take, including prescription drugs, over-the-counter medicines, and supplements.
If you miss a dose of Margenza, your doctor should give it as soon as possible and reset your schedule to keep three weeks between doses.
Margenza can harm a baby if used during pregnancy. People who can become pregnant should use effective birth control during treatment and for four months after the last dose.
It is not known whether Margenza passes into human breast milk. Because Margenza may stay in the body after treatment ends, consider the four-month washout period before breastfeeding.
These answers are fact-checked by our editorial staff.
How effective is Margenza?
In a study of people with metastatic HER2-positive breast cancer, participants had already received two or more anti-HER2 treatment regimens. Margenza plus chemotherapy delayed cancer worsening for a median of 5.8 months. This was compared with 4.9 months for trastuzumab plus chemotherapy.
The objective response rate was 22 percent with Margenza plus chemotherapy. It was 16 percent with trastuzumab plus chemotherapy.
Median overall survival did not differ much between groups. It was 21.6 months with Margenza plus chemotherapy compared with 21.9 months with trastuzumab plus chemotherapy.
What tests or monitoring are needed with Margenza for breast cancer?
Margenza can affect heart function. This can be monitored by checking left ventricular ejection fraction (LVEF) before treatment starts and every three months during treatment, as well as when treatment is completed.
If Margenza is held because of a significant drop in heart function, LVEF testing is recommended every four weeks. Monitoring during the infusion is also needed because infusion-related reactions can happen, especially during the first cycle.
On MyBCTeam, people share their experiences with breast cancer, get advice, and find support from others who understand.
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