1. What is trastuzumab deruxtecan?
Trastuzumab deruxtecan is a targeted therapy.
Targeted therapy is the name given to a group of drugs that block the growth and spread of cancer. They target and interfere with processes in the cells that help cancer grow.
Trastuzumab deruxtecan combines 2 drugs:
- A targeted therapy drug that’s very similar to, and works in the same way as, trastuzumab (Herceptin)
- Deruxtecan, a chemotherapy drug
Trastuzumab deruxtecan is the drug’s non-branded name. You may hear it called by its brand name Enhertu or its chemical name TDxd.
2. Who might be offered trastuzumab deruxtecan?
Trastuzumab deruxtecan is used to treat HER2-positive or .
You can have trastuzumab deruxtecan if you have already had 1 or more treatments specifically for HER2-positive breast cancer.
In Scotland, trastuzumab deruxtecan is also available to treat HER2-low locally advanced breast cancer or metastatic breast cancer. It is available if you have already had chemotherapy for metastatic breast cancer or if your cancer has come back within 6 months of having chemotherapy after surgery.
3. How trastuzumab deruxtecan works
Some breast cancer cells have a higher-than-normal level of a protein called HER2 on their surface, which makes them grow more quickly. This is known as HER2-positive breast cancer.
Trastuzumab attaches to the HER2 proteins and can stop the cancer cells growing. When the trastuzumab attaches to the proteins, it delivers deruxtecan directly into the breast cancer cells to kill them.
Trastuzumab deruxtecan has a “bystander effect”. This means it also kills any neighbouring cancer cells, even if they do not have a higher level of HER2 on their surface.
Trastuzumab deruxtecan also helps the body’s immune system to destroy cancer cells.
4. How trastuzumab deruxtecan is given
Trastuzumab deruxtecan is given into a vein (intravenously). This will usually be as a drip, also called an infusion, into your hand or arm.
Read about the different ways of giving chemotherapy.
You will have the first infusion over 90 minutes. Future infusions will usually be given over 30 minutes.
You’ll have trastuzumab deruxtecan as an outpatient every 3 weeks for as long as your treatment team feels you’re benefitting from the drug and any side effects are manageable.
5. Side effects of trastuzumab deruxtecan
Like any treatment, trastuzumab deruxtecan can cause side effects.
Everyone reacts differently to drugs and some people have more side effects than others. These side effects can usually be managed and those described here will not affect everyone.
You should be given a 24-hour contact number or told who to contact if you feel unwell or you are concerned about side effects at any time during your treatment, including overnight or at the weekend.
Common side effects
Effects on the blood
Trastuzumab deruxtecan can temporarily affect the number of blood cells in the body. Blood is made up of red cells, white cells and platelets.
You’ll have regular blood tests. If these show the number of blood cells is too low, your next cycle of treatment may be delayed or the dose reduced.
Doctors often tailor the dose of a drug by reducing it to suit an individual and to help manage its side effects. For some people this can help them stay on a treatment for longer.
Risk of infection
Not having enough white blood cells can increase your risk of getting an infection.
Signs of an infection
Your treatment team may give you advice on reporting signs of an infection. But generally you should contact your hospital immediately if you have any of the following:
- A high temperature (over 37.5°C) or low temperature (under 36°C)
- Suddenly feeling unwell, even with a normal temperature
- Symptoms of an infection, such as a sore throat, cough, needing to pee often or feeling cold or shivery, even if you do not have a high temperature
Before starting treatment, you should be given a 24-hour contact number or told who to contact if you feel unwell at any time during your treatment, including overnight or at the weekends.
You may need treatment if you get an infection.
Occasionally your treatment team may recommend injections of drugs called growth factors. This helps the body make more white blood cells to reduce your risk of infection.
Anaemia
Having too few red blood cells is called anaemia. If you feel breathless, dizzy or particularly tired, let your treatment team know.
Bruising and bleeding
Trastuzumab deruxtecan can reduce the number of platelets. Platelets help the blood to clot.
If your platelets are low, you may:
- Bruise more easily
- Have nosebleeds
- Notice that your gums bleed when you brush your teeth
- Take longer to stop bleeding if you cut yourself
Tell your treatment team if you have any of these symptoms.
Heart changes
Trastuzumab deruxtecan may weaken the heart muscle. This is usually temporary, but for a small number of people it may be permanent.
Contact your treatment team if you develop:
- Breathlessness
- Chest pain
- Changes to your heartbeat
- Swollen ankles
- Sudden weight gain
Before you start treatment, your treatment team will arrange a heart (cardiac) function test to make sure your heart is working normally. This could be an echocardiogram (echo) or a multiple-gated acquisition (MUGA) test.
You will continue to have heart function tests regularly during treatment.
Damage to the lungs (interstitial lung disease)
Trastuzumab deruxtecan can cause interstitial lung disease (ILD). ILD can cause inflammation in your lungs, which can lead to scarring.
Contact your treatment team straight away if you have:
- Shortness of breath
- A cough, with or without a high temperature
- Any new or worsening breathing problems, such as chest tightness or wheezing
These symptoms could have a number of causes including side effects of treatment or a lung infection. It’s important to let your treatment team know so that they can find out the cause. You may need a chest x-ray or CT scan to check what’s causing your symptoms.
Liver changes
Trastuzumab deruxtecan can affect how the liver works. You will have blood tests to check your liver function while you’re having treatment.
Sometimes treatment may need to be delayed or the dose reduced if the blood tests show any problems with your liver.
Nausea and vomiting
You may feel sick (nausea) and be sick (vomit).
Your treatment team will prescribe you anti-sickness drugs to take home to reduce nausea or stop it happening. If you continue to feel sick or vomit, tell your treatment team as they may be able to change your anti-sickness drugs.
Diarrhoea or constipation
You may have diarrhoea or constipation. Your treatment team or GP can prescribe medicine to help control it.
Contact your team if:
-
You have 3 or more episodes of diarrhoea within a 24-hour period, compared to what’s normal for you
-
You are constipated for more than 2 days
Extreme tiredness (cancer-related fatigue)
Fatigue is extreme tiredness that does not go away with rest or sleep. It’s one of the most common symptoms in people with cancer.
If you think you have fatigue, tell your treatment team or GP. They can assess you and give you advice on how to manage your energy levels.
Find out more about managing fatigue.
Sore mouth
Looking after your mouth, including your teeth and gums, is very important during treatment.
You may be given mouthwash to try to reduce soreness and stop mouth ulcers developing. It’s a good idea to use a small, soft toothbrush during this time.
See your dentist for a check-up before treatment begins.
If you need to have dental work during treatment, talk with your treatment team about the best time to have this.
If you’re having difficulty registering with a dentist, let your treatment team know.
Hair thinning or hair loss
Hair thinning and hair loss are common when having trastuzumab deruxtecan. Read more about hair loss or hair thinning.
Loss of appetite
You may lose your appetite.
Eating small frequent meals or snacks can help keep up your food intake.
If you’re concerned about how much you’re eating and drinking, ask your treatment team or GP about being referred to a dietitian.
Find out more about diet and breast cancer treatment.
Low levels of potassium in the blood
You’ll have regular blood tests before and during treatment to check your potassium levels.
If your potassium levels are low, your treatment team may prescribe supplements.
Headache
Trastuzumab deruxtecan can sometimes cause headaches. Mild pain relief such as paracetamol may help with headaches. If the headaches continue, speak to your treatment team or GP.
Dizziness
Trastuzumab deruxtecan may cause dizziness.
You should avoid driving if you feel dizzy.
If the dizziness continues, speak to your treatment team or GP.
Joint and muscle pain
Aching or pain in the joints and muscles is often mild and temporary, although for some people it’s more severe and longer lasting.
It can usually be relieved with mild pain relief like paracetamol or an anti-inflammatory drug such as ibuprofen. Before using anti-inflammatory pain relief, ask your treatment team about the correct dose, how long you should use it for and any possible side effects, especially if you have a stomach ulcer or asthma.
Exercise that gently stretches your joints or strengthens your muscles to better support your joints, such as yoga or Pilates, may help improve your symptoms.
Find out more about managing joint and muscle pain.
Other side effects
Other side effects of trastuzumab deruxtecan include:
- Changes in taste
- Skin rash
- Dry eyes
- Indigestion and increase in wind (flatulence)
Your treatment team can advise you on how to manage these.
6. Other important information
Blood clots
People with breast cancer have a higher risk of blood clots such as a deep vein thrombosis (DVT).
If you have a DVT, there’s a risk part of the blood clot could break away and travel to the lung. This is known as a pulmonary embolism (PE).
Blood clots can be life-threatening and should be treated quickly.
Blood clot symptoms
Contact your treatment team or go to your local A&E department straight away if you have any of the following symptoms:
- Pain in your arm or leg
- Redness/discolouration of the skin of the arm or leg
- Heat and swelling of the arm or leg
- Swelling, redness or tenderness where a central line is inserted to give chemotherapy, for example in the arm, chest area or up into the neck
- Shortness of breath that comes on suddenly
- Pain or tightness in the chest
- Unexplained cough or coughing up blood
Some symptoms may look different on different skin tones.
Find out more about blood clots.
Allergic reaction
Contact the 24-hour number immediately, or seek urgent medical advice such as calling 999 or attending A&E, if you notice any of the following symptoms:
- Breathlessness, wheezing, a bad cough or sudden difficulty breathing
- Tight chest or chest pain
- Swelling in your lips, tongue or throat
- Itchy red or discoloured bumps on your skin (these may be harder to see on black or brown skin)
If you have a severe reaction, treatment will be stopped immediately. If you have a less severe reaction, you may need to take medication before future treatments to reduce the risk of further reactions.
Sex, contraception and pregnancy
You can still have sex during treatment. It’s thought some drugs used to treat breast cancer cannot pass into vaginal fluids or semen, but this cannot be completely ruled out.
Most treatment teams will advise using barrier methods of contraception, such as condoms, during treatment and for a few days after chemotherapy is given.
Women should continue using contraception during treatment and for at least 7 months after their last dose of trastuzumab deruxtecan.
Men having trastuzumab deruxtecan should use effective methods of contraception during treatment and for at least 4 months after the last dose.
You’re advised not to become pregnant while having treatment because trastuzumab deruxtecan can harm a developing baby. If you have not been through the menopause, talk to your team about the most suitable method of contraception for you. It’s still possible to become pregnant even if your periods are irregular or have stopped naturally or because of treatment for breast cancer.
Fertility
If you were diagnosed with locally advanced or metastatic breast cancer before you started or completed a family, you may be concerned about your fertility. Depending on your diagnosis and treatment, you may be advised not to get pregnant.
You can talk to your treatment team about any possible fertility preservation options before starting treatment.
Breastfeeding
You’ll be advised not to breastfeed while having trastuzumab deruxtecan or within 7 months of the last dose. This is because there is a risk the drugs could be passed on through breast milk.
Travel and vaccinations
If you’re planning a holiday or need to travel overseas, check with your treatment team first.
You should not have any live vaccines while you’re having treatment.
For more information about vaccines, including COVID-19 and flu vaccines, see our information on vaccines and breast cancer.
7. Further support
Being diagnosed with locally advanced or metastatic breast cancer can make you feel lonely and isolated.
You can call our free helpline – see below – to speak to one of our specialist nurses.
You can also visit our forum to connect with people who have had a similar experience to you.
Metastatic breast cancer
Many people find it helps to talk to someone who has been through the same experience as them.
Living with Secondary Breast Cancer lets you share experiences with other people dealing with the uncertainty and challenges of metastatic breast cancer.
Find out more about our support services below.
