Trastuzumab
A humanized monoclonal antibody against HER2, used for HER2-positive breast cancer and HER2-positive stomach cancer.
Drug card
- How it works
- Binding the HER2 growth receptor on cancer cells that overexpress it
- Used for
- HER2-positive breast cancer, early or metastatic
- HER2-positive stomach or gastroesophageal junction cancer
- Known for
- Weakened heart muscle (falling ejection fraction)
- Its name
- -mab means a monoclonal antibody; -zumab means a humanized monoclonal antibody
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does trastuzumab work?
Trastuzumab is a humanized IgG1 antibody that binds the extracellular part of HER2 on cancer cells that overexpress it. This slows their growth and marks them for destruction by immune cells through antibody-dependent cellular cytotoxicity (ADCC). It is given by intravenous infusion.
Uses
What is trastuzumab used for?
- HER2-positive breast cancer, early or metastatic
- HER2-positive stomach or gastroesophageal junction cancer
Side effects
Side effects of trastuzumab
- Weakened heart muscle (falling ejection fraction)Known forSerious
- Heart failureSerious
- Abnormal heart rhythmsSerious
- High blood pressure
- Infusion reactions (fever, chills, breathlessness)Serious
- Allergic swelling (angioedema)Serious
- Lung inflammation (interstitial pneumonitis)Serious
- Lung scarring (pulmonary fibrosis)Serious
- Too little amniotic fluid, harming the fetusSerious
- Worse neutropenia during chemotherapySerious
- Diarrhea
- Infections
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Used only when an approved test shows the tumor is HER2-positive.
- LVEF is checked before the first dose and every 3 months; a significant fall means pausing or stopping treatment.
- Anthracyclines are avoided for up to 7 months after it stops, as its long washout adds to their heart toxicity.
- Pregnancy: it can cause oligohydramnios, with underdeveloped fetal lungs and newborn death; contraception is needed.
Good to know: It also comes joined to a cell-killing drug (ado-trastuzumab emtansine) and combined with pertuzumab, a HER2 antibody that stops the receptor pairing with others.
Remember it
A way to remember it
HER2 drugs can hurt the heart
The toxicity to know for HER2-targeted antibodies is weakened heart muscle with a falling ejection fraction, worst alongside anthracyclines, so heart function is checked before and during treatment.
Written for biofideX
Its name
-mab means monoclonal antibody
Older names show the source: -ximab chimeric, -zumab humanized, -umab human. WHO stopped adding that part in 2017 and dropped -mab in 2021; new names end in -tug, -bart, -ment or -mig.
-zumab means humanized monoclonal antibody
Humanized antibodies are human apart from the mouse loops (CDRs) that bind the target, as in trastuzumab (against HER2) and pembrolizumab (against PD-1). WHO stopped adding this part in 2017.
- Every drug name stem
Its class
HER2-targeted antibodies
Some breast and stomach cancers make far too much HER2, a growth factor receptor related to EGFR (HER2-positive cancers). These monoclonal antibodies bind the outside of HER2: trastuzumab slows HER2-driven growth and flags the cell for killing by immune cells (ADCC), and pertuzumab stops HER2 pairing with other HER receptors. Some are joined to a cell-killing drug that the bound cancer cell takes in.
Easily mixed up with anthracyclines, tyrosine kinase inhibitors and CD20-targeted antibodies.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Trastuzumab for injection: label (DailyMed)
- Trastuzumab (NCI Thesaurus)
- Trastuzumab (NCI)
- Pertuzumab (NCI Thesaurus)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Targeted therapy and the immune system
Trastuzumab is one of 13 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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