Lapatinib is a targeted cancer drug (biological therapy) and is also known by its brand name, Tyverb. In North America it is called Tykerb.

It is a treatment for advanced breast cancer that have large amounts of a protein called human epidermal growth factor receptor 2 (HER2). Researchers are also looking at using it to treat other types of cancer. 

You may have it with another drug. This might be one of the following:

• a type of chemotherapy called capecitabine
• trastuzumab (Herceptin)
• hormone therapy

How it works

Lapatinib is a type of targeted cancer drug (biological therapy) called a protein kinase inhibitor (TKI). It is a targeted treatment used for cancers that have large amounts of a protein called HER2 (human epidermal growth factor receptor 2). 

Some breast cancers have large amounts of HER2. They are called HER2 positive cancers. 

HER2 makes the cancer cells grow and divide. Lapatinib switches off HER2 to make the cells stop growing or die. 

How you have it

Lapatinib comes as tablets. You take them with a glass of water, either an hour before or an hour after food.  

Taking your tablets

You should take the right dose, not more or less.

Talk to your specialist or advice line before you stop taking a cancer drug.

When you have it

You take the tablets once a day. If you miss a dose, don't take an extra dose to catch up. Just take your next dose at the scheduled time. 

Tests

You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

Side effects

We haven't listed all the side effects. It is very unlikely that you will have all of these side effects, but you might have some of them at the same time.

How often and how severe the side effects are can vary from person to person. They also depend on what other treatment you are having. For example, your side effects could be worse if you are also having other drugs or radiotherapy.

When to contact your team

Your doctor or nurse will go through the possible side effects. They will monitor you closely during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

• you have severe side effects 
• your side effects aren’t getting any better
• your side effects are getting worse

Common side effects

Each of these effects happens in more than 1 in 10 people (10%). You might have one or more of them. They include:

Diarrhoea

Contact your advice line if you have diarrhoea, that is 4 loose watery poos (stools) in 24 hours. Or if you can't drink to replace the lost fluid, or if it carries on for more than 3 days. Your doctor may give you anti diarrhoea medicine to take home with you after treatment. Eat less fibre, avoid raw fruits, fruit juice, cereals and vegetables, and drink plenty of liquid to replace the fluid lost.

Skin changes

Skin problems include a skin rash, dry skin and itching. This usually goes back to normal when your treatment finishes.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. Avoiding fatty or fried foods, eating small meals and snacks, drinking plenty of water, and relaxation techniques, can all help.

Tiredness and weakness (fatigue)

Tiredness and weakness (fatigue) can happen during and after treatment - doing gentle exercises each day can keep your energy up. Don't push yourself, rest when you start to feel tired and ask others for help.

Soreness, redness and peeling on palm of hands and soles of your feet

The skin on your hands and feet may become sore, red, or may peel. You may also have tingling, numbness, pain and dryness. This is called hand-foot syndrome or palmar plantar syndrome.

Loss of appetite

You might lose your appetite for various reasons when you are having cancer treatment. Sickness, taste changes or tiredness can put you off food and drinks.

Indigestion

Contact your doctor or pharmacist if you have indigestion or heartburn. They can prescribe medicines to help.

Headaches

Tell your doctor or nurse if you keep getting headaches. They can give you painkillers to help.

Difficulty sleeping (insomnia)

It can help to change a few things about how you try to sleep. Try to go to bed and get up at the same time each day and spend some time relaxing before you go to bed. Some light exercise each day may also help. 

Pain

You might feel some pain from your muscles and joints. Speak to your doctor or nurse about what painkillers you can take to help with this.

Liver changes

You might have liver changes that are usually mild and unlikely to cause symptoms. They usually go back to normal when treatment finishes. You have regular blood tests to check for any changes in the levels of chemicals produced by the liver.

Bruising, bleeding gums or nosebleeds

This is due to a drop in the number of platelets in your blood. These blood cells help the blood to clot when we cut ourselves. You may have nosebleeds or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechia).

Hot flushes

We have some tips for coping with hot flushes and the possible treatments for men and women. Talk to your doctor if your hot flushes are hard to cope with. They might be able to prescribe you some medicines.

Cough and breathlessness

You might develop a cough or breathing problems. This could be due to infection, such as pneumonia or inflammation of the lungs (pneumonitis). Let your doctor or nurse know straight away if you suddenly become breathless or develop a cough.

Sore mouth

Mouth sores and ulcers can be painful. Keep your mouth and teeth clean; drink plenty of fluids; avoid acidic foods such as oranges, lemons and grapefruits; chew gum to keep the mouth moist and tell your doctor or nurse if you have ulcers.

Hair thinning

Your hair may thin. This is usually not noticeable by other people but can be upsetting. It usually begins thinning out gradually within 3 to 4 weeks after you start taking the drug. 

Tummy (abdominal) pain

Tell your treatment team if you have this. They may give you medicine to help. 

Occasional side effects

Each of these effects happens in more than 1 in 100 people (1%). You might have one or more of them. They include:

• constipation
• nail changes
• changes to how your heart works
• changes to how your liver works - you may have yellowing of your skin and high bilirubin levels in the blood

Rare side effects

Although rare, a severe allergic reaction can be serious and life threatening. Contact a doctor immediately if you have any of these symptoms of a severe allergic reaction.

• severe skin rash (including itchy bumpy rash)
• unusual wheezing, or difficulty breathing
• swollen eyelids, lips or tongue
• pains in muscles or joints
• collapse or blackout

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do I need to know?

Other medicines, foods and drink 

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

Grapefruit and grapefruit juice

You should not eat grapefruit or drink grapefruit juice when you are taking this drug because it can react with the drug.

Pregnancy and contraception

This treatment might harm a baby developing in the womb. It is important not to become pregnant or father a child while you're having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.

Fertility

You may not be able to become pregnant or father a child after treatment with this drug. Talk to your doctor before starting treatment if you think you may want to have a baby in the future. Men may be able to store sperm before starting treatment. Women may be able to store eggs or ovarian tissue but this is rare.

Breastfeeding

Don’t breastfeed during this treatment because the drug may come through into your breast milk.

Treatment for other conditions

Always tell other doctors, nurses, pharmacists or dentists that you’re having this treatment if you need treatment for anything else, including teeth problems.

Immunisations

Don’t have immunisations with live vaccines while you’re having treatment and for up to 12 months afterwards. The length of time depends on the treatment you are having. Ask your doctor or pharmacist how long you should avoid live vaccinations.

In the UK, live vaccines include rubella, mumps, measles, BCG, yellow fever and the shingles vaccine (Zostavax).

You can:

• have other vaccines, but they might not give you as much protection as usual
• have the flu vaccine (as an injection)
• be in contact with other people who have had live vaccines as injections

Avoid close contact with people who have recently had live vaccines taken by mouth (oral vaccines) such as oral polio or the typhoid vaccine.

This also includes the rotavirus vaccine given to babies. The virus is in the baby’s poo for up to 2 weeks and could make you ill. So avoid changing their nappies for 2 weeks after their vaccination if possible. Or wear disposable gloves and wash your hands well afterwards.

You should also avoid close contact with children who have had the flu vaccine nasal spray if your immune system is severely weakened. 

More information about this treatment

For further information about this treatment go to the electronic Medicines Compendium (eMC) website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.