Margetuximab (Margenza) is a medicine approved by the Food and Drug Administration to be given with chemotherapy to treat metastatic, HER2-positive breast cancer after treatment with at least two previous lines of targeted therapy.

Margetuximab is a monoclonal antibody, a type of medicine made in a lab that targets a specific protein, HER2, that drives the growth of some breast cancers. It falls into a class of medicines called targeted therapies.

How margetuximab works

Margetuximab works by attaching to HER2 proteins and blocking the signals that tell cells to multiply too quickly, causing cancer. Margetuximab was also engineered to encourage the immune system to kill cancer cells.

Who gets margetuximab

Margetuximab is given with chemotherapy to treat metastatic, HER2-positive breast cancer in people who have been treated with at least two previous lines of targeted therapy. At least one of those two lines have to be for treating metastatic breast cancer

How margetuximab is given

Margetuximab is given by vein once every 3 weeks until the cancer grows or you and your doctor decide to stop because of side effects. Your care team determines the dose by your weight, and the infusion is given over at least 30 minutes (120 minutes for your first infusion). It is given along with a chemotherapy chosen by you and your doctor, which will also be given by vein.

Side effects and things to remember

Common side effects while taking margetuximab include

Some people given margetuximab had an allergic reaction to getting the medicine by vein. Most reactions were minor. If you have a reaction, your doctor will give you medicine to take before future infusions to prevent the reaction.

In rare cases, margetuximab can affect your heart. Your heart function should be measured before you start treatment and monitored while you are taking margetuximab.

Margetuximab may be dangerous to a fetus if taken while pregnant. You should not take it if you are pregnant or breastfeeding, and you should take steps to avoid getting pregnant while on margetuximab.



Reviewed and updated: February 12, 2021

Reviewed by: Virginia Kaklamani MD, DSc


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