What is lapatinib?
Lapatinib (also known as Tyverb) is a targeted therapy and is one of a group of cancer drugs called tyrosine kinase inhibitors.
How does lapatinib work?
Some breast cancers have higher than normal levels of proteins (also known as receptors) called human epidermal growth factor 2 (HER2) and epidermal growth factor (HER1) also known as epidermal growth factor receptor (EGFR), which stimulate cancer cells to divide and grow.
Lapatinib is known as a dual kinase inhibitor because it targets both HER2 and HER1 receptors. It works inside the cancer cells blocking the signals that make the cells grow.
Who might be offered lapatinib?
Lapatinib may not be widely available and there are national variations on its availability. Your specialist will be able to tell you if it's likely you'll be able to receive it. Find out more about the availability of cancer drugs.
Only people whose cancer has high levels (over expression) of HER2 may benefit from having lapatinib. This is known as HER2 positive breast cancer and is found in around 20% of people with breast cancer.
Lapatinib may be used as a treatment for secondary breast cancer (breast cancer that has spread to other parts of the body). It’s usually given alongside other cancer drugs.
People who have already had treatments for HER2 positive secondary breast cancer, such as chemotherapy or trastuzumab (Herceptin) may be suitable for lapatinib, although this may be within a clinical trial alongside other drugs. When it is given for secondary breast cancer lapatinib is usually taken for as long as it is keeping the cancer under control.
Lapatinib is not currently given for primary breast cancer. However clinical trials are looking at whether it may be useful.
How do I know if I have HER2 positive breast cancer?
There are various tests to measure HER2 levels which are done on breast tissue removed during a biopsy or surgery. For most people the results are usually available within one to three weeks..
If your cancer is found to be HER2 negative, then lapatinib will not help you.
How is it given?
Lapatinib is taken as tablets orally (by mouth) once a day and should be taken every day. It’s important to take the tablets with water and according to the instructions provided by your doctor. Lapatinib should be taken at least one hour before or one hour after a meal. Lapatinib is most effective if it’s taken at the same time each day and you keep to either taking it before or after food.
If you miss a dose don’t take an extra dose to catch up. Instead, take your next dose at the usual time.
If you wish to stop taking lapatinib, talk to your specialist first.
While you are taking lapatinib you’ll have regular blood tests. These check the levels of your blood and how well your liver and kidneys are working.
What are the side effects of lapatinib?
Like any drug, lapatinib can cause side effects. However, everyone reacts differently to drugs and some people experience more side effects than others so you may not experience all or any of these. As lapatinib affects only cancer cells it has fewer side effects than chemotherapy drugs which also affect healthy cells. If you’re being given lapatinib with chemotherapy or hormone therapy, you may also have side effects from those treatments too. If you’re concerned about any side effects, regardless of whether they are listed here, talk to your specialist team..
Common side effects of lapatinib
Loss of appetite or nausea (feeling sick)
You may not feel like eating and/or you may feel sick at times during your treatment, although most people will not actually be sick. Anti-sickness tablets can help. Try to eat small regular meals if possible and have regular drinks.
Tell your specialist or GP if you have diarrhoea during treatment as they can prescribe drugs to help control it. It’s especially important to tell them if you have more than four episodes of diarrhoea in a 24-hour period. Make sure you drink plenty of fluids to avoid getting dehydrated.
Some people may experience skin problems while taking lapatinib. Always tell your doctor if you notice a rash or any skin changes. Skin problems are more likely when you are taking lapatinib with a drug called capecitabine (Xeloda). This is usually an acne-like rash and/or dry, red, itchy or peeling skin which usually affects the hands or feet (this is known as palmar-plantar syndrome). Using unperfumed soap and moisturisers can help.
You should also make sure you use sunscreen when in the sun.
Tell your doctor if you experience skin problems as they may be able to prescribe drugs to help improve them or they can adjust your treatment to minimise them.
Fatigue is extreme tiredness and exhaustion that doesn’t go away with rest or sleep and may affect you physically and emotionally. It’s a very common side effect of breast cancer treatment. Tell your doctor or palliative care team, if you have one, about the fatigue so you can be fully assessed and offered advice on how to manage your energy.
Other common side effects may include the following.
- Finding it difficult to sleep
- Muscle and joint aches and pains
- Sore mouth
- Menopausal symptoms - hot flushes and night sweats
- Abdominal pain
- Brittle or chipped nails
Less common side effects
Occasionally lapatinib can affect how the heart works, so if you are breathless or have palpitations or chest pain, you should tell your specialist team as soon as possible. Tests to check your heart function, such as an echocardiogram or multiple gated acquisition (MUGA) scan, are usually carried out before and during treatment.
Sometimes lapatinib can affect how the liver works, so if you notice any itching, yellowing of the eyes or skin (jaundice) tell your specialist team. Your liver function will be monitored using blood tests throughout the time you are taking lapatinib.
Having cancer and receiving treatment with targeted therapies like lapatinib can increase your risk of blood clots. Tell your doctor straight away if you have any swelling, pain or redness in your leg, shortness of breath or chest pains.
Rarer side effects
An allergic reaction is more likely to happen the first or second time you have lapatinib. Reactions can vary from mild to severe, although severe reactions are very rare. You may feel hot or notice skin rashes, itching, dizziness, headaches or shivering. Other symptoms include breathlessness, anxiety, flushing of the face or sudden need to pass urine. If you experience any of these symptoms you should tell your chemotherapy nurse as soon as possible.
Effects on the lungs
Rarely lapatinib can cause inflammation of the lungs which may cause shortness of breath or a cough. Tell your doctor straight away if you experience these symptoms.
Is there anything else I need to be aware of when taking lapatinib?
Talk to your specialist or pharmacist if you are taking any other prescribed or over the counter medicines as these may interact with lapatinib – particularly drugs used to treat heart problems, seizures, infections and stomach problems.
You should also discuss any complementary therapies, herbal remedies or supplements you may wish to use before you start them.
Lapatinib should not be taken with grapefruit or grapefruit juice as it may affect the way the drug works.
It's important you do not get pregnant when you are taking lapatinib as the drug could harm a developing baby.