Lapatinib (Tyverb)

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?

The growth of cancer cells is complex and we do not yet fully understand all the process involved. But we do know there are growth factors which stimulate cancer cells to divide and grow. Some breast cancers have higher than normal levels of proteins called human epidermal growth factor 2 (HER2) and epidermal growth factor (HER1).

Lapatinib is known as a dual kinase inhibitor of both HER2 and HER1, this means it can target both receptors. It works inside the cell blocking the signals for cell growth which is different to the drug trastuzumab (Herceptin) which acts on the surface of the cells.

Who might be offered lapatinib?

Only people whose cancer has high levels (over expression) of the HER2 protein may benefit from having lapatinib. This is known as HER2 positive breast cancer and is found in approximately 20 per cent of people with breast cancer.

Lapatinib is licensed as a treatment for secondary breast cancer (breast cancer that has spread to other sites in the body, also known as metastatic breast cancer). However it has not been approved for use by NICE (National Institute for Health and Clinical Excellence) or by SMC (the Scottish Medicines Consortium).

People who have already had treatments (such as chemotherapy or trastuzumab) for HER2 positive, secondary breast cancer may be suitable for lapatinib, although this will usually be within a clinical trial and may be along side another chemotherapy drug called capecitabine (Xeloda).

There are also clinical trials looking at using lapatinib to treat primary breast cancer.

Lapatinib is usually taken for as long as it is keeping the cancer under control.

How do I know if I have HER2 positive breast cancer?

There are various tests that can be done after removing a sample of breast cancer tissue to find out if you have HER2 positive breast cancer, and therefore if you could benefit from taking lapatinib.

Testing for HER2 levels is done in hospital laboratories. The results are usually available in about one to three weeks.

National guidance states that all women with primary breast cancer should have their HER2 levels tested, but, this guidance does not cover men.

If you are a man with primary breast cancer you should check with your specialist to confirm your HER2 levels will be tested. People with breast cancer that is not HER2 positive will not benefit from lapatinib at all.

How is it given?

Lapatinib is given as oral tablets which are taken once a day and you need to take the drug every day with no breaks in daily treatment. It is important to take the tablets at the same time of day, at least one hour before or one hour after a meal.

Lapatinib tables need to be stored at a room temperature which is below 30°C and should always be out of the reach of children.

What are the side effects of lapatinib?

Like any drug, lapatinib may cause side effects and some people can experience more side effects than others. As lapatinib affects only cancer cells it has fewer side effects than chemotherapy drugs which also affect healthy cells. If you are being given lapatinib with chemotherapy such as capecitabine at the same time you may have other side effects from the chemotherapy. If you have any questions about side effects, talk to your breast care nurse or specialist.

Common side effects

• Loss of appetite or nausea: You may not feel like eating or be nauseous at times during your treatment, although most people will not actually be sick. Anti-sickness tablets can help and try to eat small regular meals if possible and drinks.
• Diarrhoea: You may have diarrhoea during treatment and sometimes this can be severe. Tell your specialist or GP as they can prescribe medication to help control it.
• Skin problems: Skin problems such as an acne-like rash and dryness are a common side effect of lapatinib and you may need to use a simple moisturiser. Skin problems can be even more likely when you are taking lapatinib with capecitabine when soreness of the hands and feet can occur and you need to tell your doctor as they can prescribe medication to help improve it.
• Fatigue: You may become very tired during your treatment. If you feel like this, it is important to get plenty of rest. Sometimes gentle exercise can help to relieve fatigue.

Less common side effects

• Heart problems: Occasionally lapatinib can affect how the heart works so if you notice any problems with breathlessness, palpitations or chest pain, you need to report this to your doctor.
• Liver problems: Sometimes lapatinib can affect how the liver works so if you notice any itching, yellow eyes or skin (jaundice) you need to report this to your doctor. Your doctor will monitor the function of your liver using blood tests.

Is there anything I need to know when taking lapatinib?

Some prescription drugs need to be avoided when you are taking lapatinib. These include carbamazepine, phenytoin and ketaconazole and your doctor can advice you further.

Lapatinib should not be taken with grapefruit juice as it may alter how the drug is absorbed into the body. The herbal preparation St John's Wort should also be avoided when taking lapatinib.

It is important you do not get pregnant when you are having lapatinib. For information on contraception, see our information on fertility.