What is trastuzumab emtansine?

Trastuzumab emtansine (Kadcyla®) is made of two different drugs joined together in one drug:

  • Trastuzumab is a monoclonal antibody that works by ‘targeting’ specific proteins (receptors) on the surface of cells.
  • Emtansine is a chemotherapy drug, which damages cancer cells.

Trastuzumab emtansine is used to treat HER2 positive breast cancers that have spread or come back.

It may also be used to treat other HER2 cancers as part of a clinical trial. Trastuzumab emtansine is not the same as trastuzumab.

We have separate information about trastuzumab. It is best to read this information with our general information about:

Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

How trastuzumab emtansine is given

You will be given trastuzumab emtansine in the chemotherapy day unit or during a stay in hospital. A chemotherapy nurse will give it to you.

During treatment you usually see a cancer doctor, a cancer nurse or specialist nurse and a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information.

Before or on the day of treatment, a nurse or person trained to take blood (phlebotomist) will take a blood sample from you. This is to check that your blood cells are at a safe level to have treatment.

You will see a doctor or nurse before you have your treatment. They will ask you how you have been feeling. If your blood results are okay, the pharmacist will prepare your treatment. Your nurse will tell you when your treatment is likely to be ready.

They will check your bloods before each treatment. If your blood results are not back to normal or if you have been having certain side effects, the doctor may delay your treatment. Or sometimes they may need to lower your dose of trastuzumab emtansine.

Your nurse usually gives you anti-sickness (anti-emetic) drugs before you start treatment.

Trastuzumab emtansine can be given through:

  • a short thin tube the nurse puts into a vein in your arm or hand (cannula)
  • a fine tube that goes under the skin of your chest and into a vein close by (central line)
  • a fine tube that is put into a vein in your arm and goes up into a vein in your chest (PICC line).

The nurse will give you trastuzumab emtansine as a drip into the vein (intravenous infusion). Some people can have a reaction to trastuzumab emtansine, so the first infusion is given slowly over 90 minutes. If you do not have any problems with the first treatment, you can have the following infusions over about 30 minutes.

Your course of treatment

You usually have trastuzumab emtansine as a course of several cycles of treatment over a few months. Each cycle usually takes 21 days (3 weeks).

You have trastuzumab emtansine on the first day of the cycle. You will then have a rest period for 20 days. After the 21 days are complete, you start your second cycle of treatment.

Trastuzumab emtansine is given for as long as it is working. Your doctor or nurse will tell you more about the number of cycles you are likely to have.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects. You may get some of the side effects we mention, but you are unlikely to get all of them.

If you are having trastuzumab with chemotherapy, you are more likely to get these side effects. If you are also having treatment with other cancer drugs, you may also have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

Serious and life-threatening side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Side effects while treatment is being given

Allergic reaction

Some people have an allergic reaction while having this treatment. Signs of a reaction can include:

  • feeling hot or flushed
  • a skin rash
  • itching
  • shivering
  • feeling dizzy
  • a headache
  • feeling breathless
  • swelling of your face or mouth
  • pain in your back, tummy or chest.

Your nurse will check you for signs of a reaction during your treatment. If you feel unwell or have any of these signs, tell them straight away. If you do have a reaction, it can be treated quickly.

Sometimes a reaction can happen a few hours after treatment. If you get any signs or feel unwell after you get home, contact the hospital straight away.

Common side effects

Risk of infection

This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If the number of white blood cells is low, you are more likely to get an infection. A low white blood cell count is called neutropenia.

If you have an infection, it is important to treat it as soon as possible. Contact the hospital straight away on the 24-hour contact number you have if:

  • your temperature goes over 37.5°C (99.5°F)
  • you suddenly feel unwell, even with a normal temperature
  • you have symptoms of an infection.

Symptoms of an infection include:

  • feeling shivery
  • a sore throat
  • a cough
  • diarrhoea
  • needing to pass urine often.

It is important to follow any specific advice your cancer treatment team gives you.

You will have regular blood tests during treatment. If your white blood cell count is low, your doctor may reduce or delay your treatment for a short time.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. 

Tell your doctor if you have any bruising or bleeding that you cannot explain. This includes:

  • nosebleeds
  • bleeding gums
  • tiny red or purple spots on the skin that may look like a rash.

Some people may need a drip to give them extra platelets. This is called a platelet transfusion.

Anaemia (low number of red blood cells)

This treatment can reduce the number of red blood cells in your blood. These cells carry oxygen around the body. If the number of red blood cells is low, you may be tired and breathless. Tell your doctor or nurse if you feel like this. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.

Tiredness

Feeling tired is a common side effect. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can give you more energy. If you feel sleepy, do not drive or operate machinery.

Feeling sick

You may feel sick in the first few days after treatment. Your doctor may give you anti-sickness drugs to help prevent or control sickness. Take the drugs exactly as your nurse or pharmacist tells you. It is easier to prevent sickness than to treat it after it has started.

If you feel sick, take small sips of fluids and eat small amounts often. If you continue to feel sick, or if you vomit more than once in 24 hours, contact the hospital as soon as possible. They will give you advice and may change the anti-sickness drug to one that works better for you.

Constipation

This treatment can cause constipation. Here are some tips that may help:

  • Drink at least 2 litres (3½ pints) of fluids each day.
  • Eat high-fibre foods, such as fruit, vegetables and wholemeal bread.
  • Do regular gentle exercise, like going for short walks.

If you have constipation, contact the hospital for advice. Your doctor can give you drugs called laxatives to help.

Diarrhoea

If you have diarrhoea, your doctor can give you drugs to help control it. It is important to take them exactly as your nurse or pharmacist explains. Try to drink at least 2 litres (3½ pints) of fluids every day.

Rarely, diarrhoea can be more severe. But it is important to contact the hospital if this happens. If you have more than 3 episodes of diarrhoea a day, contact the hospital on the telephone numbers you have been given and speak to a doctor or nurse.

Tummy pain

Tell your doctor or nurse if you get pain or discomfort in your tummy (abdomen). Your doctor can prescribe drugs to help improve these symptoms.

Dry mouth

You may get a dry mouth. Drink plenty of fluids and add sauces and gravies to your food to keep it moist. If you have dry lips, using a lip balm or Vaseline® can help.

Sore mouth

You may get a sore mouth or mouth ulcers. This can make you more likely to get a mouth infection.

Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals.

If your mouth is sore:

  • tell your nurse or doctor – they can give you a mouthwash or medicines to help
  • try to drink plenty of fluids
  • avoid alcohol, tobacco, and foods that irritate your mouth.

Numb or tingling hands or feet (peripheral neuropathy)

This treatment affects the nerves, which can cause numb, tingling or painful hands or feet. You may find it hard to fasten buttons or do other fiddly tasks.

Tell your doctor if you have these symptoms. They sometimes need to lower the dose of the drug. The symptoms usually improve slowly after treatment finishes, but for some people they may never go away. Talk to your doctor if you are worried about this.

Muscle or joint pain

You may get pain in your muscles or joints. If this happens, tell your doctor so they can give you give you painkillers. Tell them if the pain does not get better. Having warm baths and taking regular rests may help.

Skin changes

You may develop a rash and your skin may become dry and itchy. Your doctor can prescribe medicine or creams to help.

Tell your doctor if a rash gets worse or does not improve.

Headaches

This treatment may cause headaches. If this happens, tell your doctor or nurse. They can give you painkillers.

Effects on the nervous system

This treatment can affect the nervous system. You may feel confused, dizzy or unsteady. Tell your doctor or nurse straight away if you notice this.

Low levels of potassium

Trastuzumab emtansine can lower the levels of potassium in your blood. This is usually mild and goes back to normal after treatment. You will have blood tests before and during treatment to check your potassium levels. Your doctor can give you potassium supplements if you need them.

Eye problems

Your eyes may become watery or you may get blurred vision. Tell your doctor if your eyes become red and inflamed (conjunctivitis). You may need antibiotic eye drops. Always tell your doctor or nurse if you notice any changes in your eyes or vision.

Hair loss

Your hair may get thinner but you are unlikely to lose all the hair from your head. Hair loss usually starts after your first or second treatment. It is almost always temporary and your hair will usually grow back after treatment ends. Your nurse can talk to you about ways to cope with hair loss.

Soreness and redness of palms of hands and soles of feet

This is called palmar-plantar or hand-foot syndrome. It gets better when treatment ends. Your doctor or nurse can give you advice and prescribe creams to improve the symptoms. It can help to keep your hands and feet cool and to avoid heat, hot water and tight-fitting socks, shoes and gloves.

Effects on the heart

Chemotherapy can affect the way the heart works. You may have tests to see how well your heart is working. These may be done before, during and sometimes after treatment. If the treatment is causing heart problems, your doctor can change the type of chemotherapy you are having.

Contact a doctor straight away if you:

  • have pain or tightness in your chest
  • feel breathless or dizzy
  • feel your heart is beating too fast or too slowly.

Other conditions can cause these symptoms, but it is important to get them checked by a doctor.

Less common side effects

Effects on the lungs

This treatment can cause changes to the lungs. Tell your doctor if you develop:

  • a cough
  • wheezing
  • a fever (high temperature)
  • breathlessness.

You should also tell them if any existing breathing problems get worse. You may have tests to check your lungs.

If your symptoms come on suddenly, contact the hospital immediately. You may have inflammation of the lungs (pneumonitis). Your doctor can tell you more about this.

Effects on the liver

Trastuzumab emtansine may affect how your liver works. This is usually mild and goes back to normal after treatment. You are unlikely to notice any changes, but your doctor will check how well your liver is working with regular blood tests.

Other information about trastuzumab

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • pain, redness or swelling in a leg or arm
  • breathlessness
  • chest pain.

If you have any of these symptoms, contact a doctor straight away.

A blood clot is serious, but can be treated with drugs that thin the blood. Your doctor or nurse can give you more information.

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.

Contraception

Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment and for at least 7 months afterwards. The drugs may harm the developing baby. It is important to use effective contraception.

Breastfeeding

Women are advised not to breastfeed while having this treatment and for at least 7 months afterwards. This is because the drugs could be passed to the baby through breast milk.

Fertility

It is not known if trastuzumab may affect your fertility (your ability to get pregnant or father a child). If you are worried about this, you can talk to your doctor or nurse before treatment starts.

Sex

If you have sex in the first few days after having treatment, you need to use a condom. This is to protect your partner in case there is any of the drug in semen or vaginal fluids.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.

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