Larotrectinib (Vitrakvi)

Larotrectinib is a type of targeted cancer drug . It is pronounced lar-oh-trek-tih-nib. You might also hear it called a:

• histology independent therapy (HIT)
• tumour agnostic therapy

HITs are a newer type of treatment. They treat cancers with specific gene changes. Usually, cancers are treated depending on where they start in the body.

Larotrectinib is a treatment for solid cancers that have a change to the neurotrophic tyrosine receptor kinase (NTRK) gene and:

• are locally advanced or advanced (metastatic)
• are not able to be removed as an operation would cause severe health problems
• other treatments have not worked or are not suitable

How does larotrectinib work?

Larotrectinib is a type of targeted cancer drug called a tyrosine kinase inhibitor (TKI). Tyrosine kinases are proteins. Cells use these proteins to tell other cells to grow. They act as chemical messengers. Blocking these messages helps to slow or stop the cancer from growing.

There are several different tyrosine kinases. Your doctor will test your cancer cells before you have this treatment. The tests look for changes in these proteins or genes. For larotrectinib they look for the NTRK gene change.

How do you take larotrectinib?

You take larotrectinib as capsules or as a liquid that you swallow. You swallow the capsules whole with a glass of water. You can take them with or without food.

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

Talk to your healthcare team before you stop taking a cancer drug, or if you have missed a dose.

How often do you take larotrectinib?

You take larotrectinib twice a day.

You take it for as long as it’s working, and the side effects aren’t too bad.

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.

Before treatment starts you may have a blood test to check for viruses such as hepatitis B, hepatitis C, and HIV . This is called a viral screen.

It’s important for your doctor to know if you have had any of these viruses. This is because this treatment can weaken your immune system and can cause the virus to become active again (reactivation). 

If you can get pregnant, you will be asked to have a pregnancy test.

What are the side effects of larotrectinib?

Side effects can vary from person to person. They also depend on what other treatments you're having. 

When to contact your team

Your doctor, nurse or pharmacist will go through the possible side effects. They will monitor you 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

Early treatment can help manage side effects better. 

We haven't listed all the side effects here. Talk to your healthcare team if you have any new symptoms that you think might be a side effect of your treatment.

Remember it is very unlikely that you will have all of these side effects. But you might have some of them at the same time.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:

Breathlessness and looking pale

You might be breathless and look pale due to a drop in red blood cells. This is called anaemia.

Increased risk of infection

Increased risk of getting an infection is due to a drop in white blood cells. Symptoms include a change in temperature, aching muscles, cough, headaches, feeling cold and shivery, pain or a burning feeling when peeing, or generally feeling unwell. You might have other symptoms depending on where the infection is.

Infections can sometimes be life threatening. You should contact your advice line urgently if you think you have an infection. 

Liver changes

You might have liver changes that are usually mild and unlikely to cause symptoms. There isn't enough information to work out if this treatment can cause long term liver damage.

You have regular blood tests throughout your treatment so your doctor can check this.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.

It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.

Constipation

Constipation is easier to sort out if you treat it early. Drink plenty and eat as much fresh fruit and vegetables as you can. Try to take gentle exercise, such as walking. Tell your healthcare team if you think you are constipated. They can give you a laxative if needed.

Diarrhoea

Contact your advice line if you have diarrhoea. For example, in one day you have 2 or more loose bowel movements than usual. If you have a stoma , you might have more output than normal. Your doctor may give you anti diarrhoea medicine to take home with you after treatment.

Try to eat small meals and snacks regularly. It’s best to try to have a healthy balanced diet if you can. You don’t necessarily need to stop eating foods that contain fibre. But if your diet is normally very high in fibre, it might help to cut back on high fibre foods such as beans, nuts, seeds, dried fruit, bran and raw vegetables. 

Drink plenty to try and replace the fluid lost. Aim for 8 to 10 glasses per day.

Tiredness

You might feel very tired and as though you lack energy.

Various things can help you to reduce tiredness and cope with it, for example exercise. Some research has shown that taking gentle exercise can give you more energy. It is important to balance exercise with resting.

Dizziness

This drug might make you feel dizzy. Tell your healthcare team straight away if you get this. Don’t drive or operate machinery if you feel dizzy.

Weight gain

You may gain weight while having this treatment. You may be able to control it with diet and exercise. Tell your healthcare team if you are finding it difficult to control your weight. 

Muscle pain

You might have muscle pain during treatment. Let your treatment team know so they can advise you on how to reduce it.

Occasional side effects

• bruising, bleeding gums or nosebleeds due to a drop in the number of platelets in your blood. You may also have lots of tiny red spots or bruises on your arms or legs (petechiae)
• changes to the way you walk (your gait). Tell your healthcare team straightaway if you're finding it difficult to walk
• numbness or tingling in fingers or toes is often temporary and can improve after you finish treatment. Tell your healthcare team if you're finding it difficult to walk or complete fiddly tasks such as doing up buttons
• taste changes may make you go off certain foods and drinks. You may also find that some foods taste different from usual or that you prefer to eat spicier foods. Your taste gradually returns to normal a few weeks after your treatment finishes
• muscle weakness (myasthenia) in different parts of the body

Possible rare and long term side effects

This is a new drug in cancer treatment. So there is limited information available at the moment about possible rare and longer term effects that it may cause. Tell your doctor if you notice anything that is not normal for you.

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 medicines, herbal products, and some food and drinks. We are unable to list all the possible interactions that may happen. An example is grapefruit or grapefruit juice which can increase the side effects of certain drugs.

Tell your healthcare team about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies. Also let them know about any other medical conditions or allergies you may have.

Loss of fertility

It is not known whether this treatment affects fertility in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

Pregnancy and contraception

This drug may harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you are having treatment with this drug and for at least a month afterwards.

Doctors don’t know if larotrectinib stops the contraceptive pill, injection or implant working properly. If you are using one of these, you should also use a barrier method of contraception like condoms during sex.

Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner become pregnant while having treatment.

Breastfeeding

Don’t breastfeed during this treatment and for 3 days after your last dose. This is because the drug may come through into your breast milk.

Other conditions

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.

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, and yellow fever.

You can usually have:

• other vaccines, but they might not give you as much protection as usual
• the flu vaccine (as an injection)
• the coronavirus (COVID-19) vaccine

Talk to your doctor or pharmacist about the best time to have a vaccine in relation to your cancer treatment.

Contact with others who have had immunisations 

You can be in contact with other people who have had live vaccines as injections. If someone has had a live vaccine by mouth or nasal spray there may be a small risk the vaccine virus can be passed onto you if your immune system is weakened.

Your healthcare team will let you know if you need to take any precautions if you are in close contact with someone who has had a live vaccine.

More information about this treatment

For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.

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