Also called T-DM1, a HER2 antibody-drug conjugate for breast cancer
Trastuzumab emtansine
A targeted breast cancer treatment that delivers chemotherapy directly to HER2-positive cancer cells, given by drip.
What is Trastuzumab emtansine?
Trastuzumab emtansine, often called T-DM1, is a specialist treatment for HER2-positive breast cancer. It joins together a targeted antibody (trastuzumab) and a chemotherapy medicine, so the antibody carries the chemotherapy straight to cancer cells that carry the HER2 marker. It is given as a drip into a vein. Its most important risks are liver problems, effects on the heart's pumping (which is monitored with heart scans), and a fall in platelets that can raise the risk of bleeding and bruising. It is different from plain trastuzumab and the two are not interchangeable. It is given under specialist cancer care, with contraception important because it can harm an unborn baby.
Education and reference only. This is a plain-language guide to Trastuzumab emtansine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Trastuzumab emtansine, also called T-DM1, is an antibody-drug conjugate used to treat HER2-positive breast cancer, a type of breast cancer with extra amounts of a protein called HER2 on its cells. It is made by linking the targeted antibody trastuzumab to a chemotherapy medicine (emtansine). The antibody acts like a homing device, attaching to HER2 on cancer cells and carrying the chemotherapy inside them, which limits damage to healthy cells. It is given as an infusion (drip) into a vein under the care of a specialist cancer team. It is not the same medicine as plain trastuzumab and the two cannot be swapped for each other.
How it works
Trastuzumab emtansine targets cancer cells that carry large amounts of HER2. The trastuzumab part attaches to HER2 on the surface of the cancer cell; the whole medicine is then taken inside the cell, where the chemotherapy part (emtansine) is released to damage the cell's internal machinery and kill it. By delivering the chemotherapy mainly to HER2-positive cancer cells, it aims to be more targeted than ordinary chemotherapy. However, the chemotherapy component and the HER2-targeting both contribute to its key risks, which include liver problems, a fall in platelets (raising bleeding risk), and a weakening of the heart's pumping action.
Company & origin
Originated / developed by: Specialist manufacturer.
A specialist breast cancer treatment used in the UK for HER2-positive breast cancer, combining a targeted antibody with chemotherapy in one medicine.
Practical use
How to take Trastuzumab emtansine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as a drip into a vein in a cancer day unit, on a schedule set by your specialist team.
- Attend all appointments for blood tests and heart scans, which check your liver, platelets and heart function.
- Report any easy bruising, nosebleeds, bleeding gums or blood in your urine or stools, as these can signal low platelets.
- Report breathlessness, swollen ankles, a fast or irregular heartbeat or rapid weight gain, as these can signal heart strain.
- Use effective contraception during treatment and for the period your team advises, as it can harm an unborn baby.
Weighing it up
Advantages & disadvantages of Trastuzumab emtansine
Advantages
- Delivers chemotherapy directly to HER2-positive breast cancer cells, sparing more healthy cells than ordinary chemotherapy.
- An established targeted treatment for HER2-positive breast cancer.
- Given as a drip on a regular schedule under specialist care.
Disadvantages
- Can affect the liver, the heart's pumping action and the platelet count, all of which need monitoring.
- Reactions can occur during the infusion, and it can harm an unborn baby.
- Is not interchangeable with plain trastuzumab, which can cause confusion if not made clear.
Practical use
Good to know
There are three safety points that stand out with trastuzumab emtansine. First, it can affect the liver, so liver blood tests are checked before each treatment. Second, it can weaken the heart's pumping action, so heart scans to measure how well the heart pumps are done before and during treatment, and any breathlessness, swollen ankles or rapid weight gain should be reported. Third, it can lower platelets, the cells that help blood clot, which can cause easy bruising and bleeding, so unusual bruising, nosebleeds or bleeding gums should be reported. It is important to know that it is a different medicine from plain trastuzumab and the two are not interchangeable. Reactions can happen during the drip. Because it can harm an unborn baby, effective contraception is important during treatment and for a period afterwards.
Who should not take it / use with caution
- People who have had a serious allergic reaction to trastuzumab emtansine should not receive it.
- It is used with great care, or avoided, in people with significant liver problems, a low platelet count or a weak heart.
- It is avoided in pregnancy because it can harm an unborn baby; it is given only under specialist cancer care.
Monitoring
- Liver blood tests and a platelet count before each treatment.
- Heart scans to measure the heart's pumping action before and during treatment.
- Watching for bleeding, breathlessness, swelling or other side effects, and reviewing the cancer's response.
Side effects
- Tiredness, nausea, muscle and joint aches, and headache.
- A fall in platelets causing easy bruising or bleeding, and abnormal liver blood tests.
- A weakening of the heart's pumping action, which may cause breathlessness or swollen ankles.
- Less commonly but seriously, severe liver injury, serious bleeding, lung inflammation or nerve damage causing numbness and tingling.
Key interactions
- Medicines that can affect the liver may add to the strain on the liver, so tell your team about everything you take.
- Certain other medicines may increase the risk of side effects from the chemotherapy part; your team will check this.
- Other medicines that affect bleeding or the platelet count should be reviewed with your specialist team.
Available as: A powder made up into a solution and given as a drip (infusion) into a vein.
Answers
Trastuzumab emtansine: frequently asked questions
What is trastuzumab emtansine used for?
It is a targeted treatment for HER2-positive breast cancer that delivers chemotherapy directly to cancer cells carrying the HER2 marker.
Is it the same as trastuzumab?
No. Trastuzumab emtansine (T-DM1) links trastuzumab to a chemotherapy medicine; it is a different medicine and the two are not interchangeable.
Why do I need heart scans?
It can weaken the heart's pumping action, so heart scans are done before and during treatment, and any breathlessness or swollen ankles should be reported.
Why is my platelet count checked?
It can lower platelets, the cells that help blood clot, which can cause easy bruising and bleeding, so the count is monitored and any unusual bleeding reported.
Do I need contraception?
Yes. It can harm an unborn baby, so effective contraception is important during treatment and for the period your team advises.
Authoritative sources
- BNF
- NICE CKS
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