Tebentafusp (Kimmtrak)

Tebentafusp is a type of immunotherapy. You pronounce it as teh-ben-tah-fusp. It is also called Kimmtrak.

It is a treatment for a type of eye cancer called uveal melanoma. You have this treatment if your cancer tests positive for the human leukocyte antigen (HLA) protein . This protein is called HLA-A*02:01 and is on the surface of some melanoma cells.

You may have it in one of the following situations. Your cancer:

• can’t be removed by surgery (unresectable)
• has spread to other parts of the body (metastatic)

How does tebentafusp work?

Tebentafusp is a type of immunotherapy called a bispecific T-cell engager (BiTE) .

Tebentafusp binds to a protein on the healthy T cells (immune cells that kill cancer cells) and a protein on the melanoma cells. This helps stimulate the body's immune system to kill the melanoma cells.

How do you have tebentafusp?

You have tebentafusp as a drip into your bloodstream (intravenously).

You might have treatment through a long plastic tube that goes into a large vein in your chest. The tube stays in place throughout the course of treatment. This can be a:

• central line
• PICC line
• portacath

If you don't have a central line

You might have treatment through a thin short tube (a cannula) that goes into a vein in your arm. You have a new cannula each time you have treatment.

How often do you have tebentafusp?

You have tebentafusp as cycles of treatment. This means that you have the drug and then a rest to allow your body to recover.

Each cycle of treatment lasts 21 days (3 weeks). You have it on days 1, 8 and 15 of each cycle. You have tebentafusp for as long as the treatment is working, and you are not experiencing too many side effects.

The dose of tebentafusp is gradually increased during your first cycle. This is to help reduce the risk of a side effect called cytokine release syndrome (CRS) .

CRS can cause a number of symptoms, one of which is a drop in blood pressure. You may have extra fluids through a drip before you start treatment. This helps to prevent low blood pressure.

You usually stay in hospital for the first 3 treatments of tebentafusp. This is so the team looking after you can check for side effects. After that, you have the rest of your treatment in a day unit or outpatient clinic.

You have tebentafusp in the following way:

Cycle 1

Cycle 2 onwards

You then start your next cycle of treatment.

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). 

You will have an ECG before and after the first 3 treatments. Thereafter, you may have it if needed.

What are the side effects of tebentafusp?

Side effects can vary from person to person. They also depend on what other treatment you are having. 

When to contact your team

Your doctor, pharmacist 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

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:

Cytokine release syndrome (CRS)

Cytokines are a group of proteins in the body that play an important part in boosting the immune system. This treatment stimulates the immune system to make large amounts of cytokines. This can cause symptoms which can be severe. Some of the symptoms include fever, chills, a headache, difficulty breathing, and dizziness.

Skin and hair changes

You might notice skin changes, such as dryness, itching and rashes similar to acne on your face, neck and chest. 

Other changes include skin or hair turning lighter or darker. This may include eyelashes and the inner, coloured layer of the eye (retina).

Tell your healthcare team if you have any rashes, itching or notice any colour changes to your skin. Don't go swimming if you have a rash because the chlorine in the water can make it worse.

If your skin gets dry or itchy, using unperfumed moisturising cream may help. Check with your doctor or nurse before using any creams or lotions. Wear a high factor sunblock if you’re going out in the sun.

High temperature or chills

High temperature (fever, shivering or chills) can happen with this drug. This is because it can affect your body’s ability to control temperature. Having a fever with this drug doesn’t always mean you have an infection. But you should call your advice line, as an infection can be serious if not treated quickly.

Tiredness and weakness

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.

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.

Pain in different body parts

You may have pain in your muscles, joints, back, arms or legs, or tummy.

Less commonly, you may have muscle spasms or pain in your mouth or throat.

Tell your healthcare team if you have this. They can prescribe painkillers.

 Swelling in different parts of the body

You may have swelling to different parts of the body, including your face, eyes, lips, back of the throat (pharynx), or your hands and feet. This is due to a build up of fluid (oedema).

Contact your hospital advice line, 999, or visit an Accident and Emergency (A&E) if you have difficulty breathing due to swelling in your throat.

Blood pressure changes

During treatment, your blood pressure may be lower or higher than usual. Your nurse will check this regularly. Your blood pressure usually goes back to normal either during treatment or when your treatment ends. 

Headaches

Tell your healthcare team if you keep getting headaches. They can give you painkillers to help.

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 weeing, 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. 

Loss of appetite

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

Changes to the levels of substances in the blood

You may have low levels of minerals or salts in your blood, such as low magnesium, sodium, calcium, potassium and phosphate. Or the levels of an enzyme , such as lipase, may go up.

Less commonly, the level of the enzyme amylase may go up.

You have regular blood tests during treatment to check this.

Sleeping problems (insomnia)

This treatment may cause difficulty falling asleep or staying asleep.

Dizziness

This drug might make you feel dizzy. Don’t drive or operate machinery if you have this.

Numbness or tingling in different body parts

Numbness or tingling in different parts of the body 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.

Changes to your heart rate

This treatment may cause a fast heart rate (tachycardia). You may have palpitations, chest pain, breathlessness, or feel faint or lightheaded.

Less commonly, you may have an irregular heartbeat. You will have tests, such as an ECG, to check this.

Skin flushing

The skin in your face, neck or upper chest may suddenly become red.

Cough or breathlessness

It is important to tell your doctor or nurse if you have a cough, or are breathless.

Diarrhoea or constipation

Tell your healthcare team if you have diarrhoea or constipation. They can give you medicine to help. 

Indigestion

This treatment may cause indigestion (dyspepsia). Indigestion is an upset stomach and can feel like:

• discomfort, burning or bloating in the upper tummy (abdomen)
• feeling full early during your meal
• feeling uncomfortably full after a meal

Tell your healthcare team if you feel like this. They can prescribe medications to help relieve the symptoms.

Flu-like symptoms

You might have flu-like symptoms such as fever, chills and muscle aches.

Contact your advice line if you have flu-like symptoms and check if you can take paracetamol.

Liver changes

The changes are usually very mild and unlikely to cause symptoms. They will almost certainly go back to normal when treatment is finished. 

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

Breathlessness and looking pale

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

Occasional side effects

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:

• feeling anxious – symptoms may include feeling nervous or tense, having a faster heartbeat, or feeling lightheaded and dizzy
• taste changes may make you go off certain foods and drinks. Speak to your healthcare team if you have this. They can refer you to a dietician
• low levels of oxygen in your blood and body tissues. Symptoms may include confusion, bluish skin, fingernails or lips, difficulty breathing or having a fast heart rate
• hair loss - you could lose all your hair or it may become thinner
• night sweats
• kidney changes – you will have regular blood tests to check how well they are working
• increased levels of white blood cells – you have regular blood tests to check this

Rare side effects

These side effects happen in fewer than 1 in 100 people (less than 1%). You might have one or more of them. They include:

• changes to the levels of chemicals in your blood due to the breakdown of tumour cells (tumour lysis syndrome) - you have regular blood tests to check for this

• chest pain or discomfort (angina). Tell your healthcare team if you have chest pains

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 you need to know

Other medicines, food 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 your womb. It is important not to become pregnant during treatment and for at least 1 week afterwards. Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you become pregnant while having treatment.

Breastfeeding

It is not known whether this drug comes through into the breast milk. Doctors usually advise that you don’t breastfeed during this treatment.

Treatment for 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.