Tebentafusp (Kimmtrak)

Tebentafusp at a glance

Tebentafusp is a T-cell-engaging immunotherapy given as an intravenous infusion. A blood test for HLA-A*02:01 is essential before treatment. The first three infusions require prolonged observation because cytokine release syndrome can occur after the drip has finished.

This guide helps you prepare, manage everyday problems and recognise urgent symptoms. Your centre’s written dosing, observation and discharge plan remains essential.

What is tebentafusp, and how does it work?

Tebentafusp brings immune T cells close to target cells by recognising a gp100 peptide displayed by HLA-A*02:01 and CD3 on T cells. This helps the T cells attack the cancer cells. It is different from a checkpoint inhibitor, conventional chemotherapy or a medicine made from your own modified cells.

The immune activation that helps attack cancer can also release inflammatory signals. Treatment is therefore introduced and monitored carefully. Not every targeted antibody works this way, so instructions for another antibody medicine cannot be substituted.

How your team decides whether it is suitable

Tebentafusp is used for adults with HLA-A*02:01-positive uveal melanoma, a melanoma arising inside the eye, that cannot be removed surgically or has spread. Your oncologist checks your test result, disease and overall health before recommending treatment.

You must have the appropriate HLA-A*02:01 result for this treatment. This is a marker involved in how cells display protein fragments to the immune system; it is not the same as a PD-L1 test. Your team also reviews liver tests, blood pressure, heart health, fluid balance and other medicines.

Before treatment starts

Before starting, the team confirms your HLA-A*02:01 result and checks liver function, blood pressure, heart health, kidney function and blood tests as appropriate. Tell them about heart rhythm problems, low blood pressure, adrenal insufficiency, current steroid treatment, allergies or a recent infection. Bring all prescriptions, non-prescription medicines and supplements.

Discuss transport, possible overnight stays and support at home before the first infusion. You need a working thermometer and clear instructions for contacting your hospital's urgent oncology service. Carry the treatment alert card and show it to other clinicians.

How treatment is given

The usual doses rise from 20 micrograms at the first weekly infusion to 30 micrograms at the second and 68 micrograms at the third. Later treatment is generally 68 micrograms once weekly. The drip runs over approximately 15 to 20 minutes. The units are micrograms, not milligrams.

The first three infusions are given with immediate access to treatment for severe reactions and at least 16 hours of monitoring after each infusion. This is a much longer visit than the drip itself. Later doses may be managed as outpatient visits if the earlier doses were tolerated appropriately, with observation according to the product information and your condition.

The team checks hydration and blood pressure and may adjust blood-pressure medicines for dose days. Do not stop these medicines on your own. A reaction can lead to delayed dosing and a revised monitoring plan.

Practical care during the course

Arrange overnight or extended-stay support for the first three weekly treatments. Bring an updated medicines list and tell staff about dizziness, fever, rash, chills or breathlessness even if the infusion has already ended. Have a clear discharge plan and a way to return promptly if symptoms develop later.

Skin reactions are particularly common because gp100 is also present in normal pigment-producing cells. Changes in skin colour can occur. Use gentle skin care and prescribed creams or antihistamines rather than trying several new products at once. Report painful, extensive or rapidly worsening reactions.

Monitoring and checking whether treatment is working

Observation checks include temperature, pulse, blood pressure, breathing and oxygen levels. Monitoring continues after the infusion because cytokine release syndrome can start later.

Blood tests check liver enzymes and bilirubin, alongside blood counts, kidney function and blood salts as needed. Heart rhythm also needs attention: European product information recommends an electrocardiogram (ECG) before and after treatment during the first three weeks, then when clinically indicated. Your team should explain the monitoring schedule for your product and health conditions.

Scans and clinical assessments help the team assess benefit. A fever or rash does not prove treatment is working. Side effects can require treatment to be delayed or stopped; let the team decide how to resume after an interruption.

Common side effects and how to manage them

Tebentafusp can cause the effects below. Not everyone experiences every effect, and your team can help you manage them.

Tiredness and reduced stamina

Plan short periods of activity with rests and accept help during the early treatment phase. Gradually increase activity as your team advises. Sudden or profound tiredness, especially with dizziness, fever or breathlessness, needs assessment rather than being attributed automatically to treatment.

Fever, chills and aching

These can occur with immune activation, but can also indicate infection. Check your temperature and contact the oncology service using your emergency plan. Do not repeatedly take paracetamol to hide a fever. Staff may recommend it as a premedicine or for a reaction, but home fever needs the agreed assessment first.

Nausea, appetite change and bowel symptoms

Use prescribed anti-sickness medicine and try small meals and regular drinks, within any fluid restriction. Report persistent vomiting or diarrhoea. Inability to keep fluids or important medicines down needs urgent advice. Constipation can follow reduced activity or other medicines; request a suitable plan before it becomes severe.

Skin and administration-site reactions

Rash, itching or soreness at an injection or line site can occur. Use gentle washing, avoid rubbing and show the area to staff. Increasing heat, spreading redness, discharge or fever may suggest infection. Widespread hives, facial swelling, wheezing or collapse needs immediate help.

Blood-test changes

Anaemia and a fall in lymphocyte count can occur. Blood tests also check liver function, kidney function and blood salts. Keep your appointments and report new breathlessness, marked fatigue or signs of infection.

Less common but important side effects

Cytokine release syndrome

Tebentafusp activates T cells, which release messenger proteins called cytokines. This can cause cytokine release syndrome (CRS), with fever, shaking, a fast heartbeat, low blood pressure or breathing problems. It is particularly important around the first three doses and needs prompt assessment. Starting with smaller doses and prolonged observation help the team manage the risk.

The team checks hydration and may give intravenous fluids before treatment. Steroids or other medicines may be needed to treat a reaction or before a later dose, depending on what happened previously. Do not diagnose a fever as “just CRS”: infection and other causes also need consideration.

Skin reactions

Rash, itching, redness and skin swelling are common, especially after early infusions. Report painful, extensive or worsening reactions. The team may prescribe antihistamines or steroid creams; more marked reactions can require additional treatment or a delay in the next infusion.

Liver and heart problems

Liver enzymes can rise, sometimes before symptoms develop, so blood tests matter even when you feel well. Report yellow skin or eyes, dark urine or new abdominal pain. Fast or irregular heartbeats and changes in the heart's electrical rhythm can also occur. New chest pain, fainting or severe breathlessness needs emergency assessment.

Rapid breakdown of cancer cells

Tumour lysis syndrome is listed as an uncommon reaction in European product information. It can disturb blood salts and affect the kidneys or heart. Report reduced urine, persistent vomiting, muscle cramps or an irregular heartbeat promptly. Severe confusion or a seizure requires emergency help.

New neurological symptoms or signs of infection need urgent assessment, whatever their cause. Do not assume that every side effect described for another T-cell-engaging medicine applies to tebentafusp.

Other medicines, supplements and vaccinations

Give the pharmacist a complete medicine list before starting and whenever something changes. Cytokine release can temporarily change how the body processes some medicines, especially in the first 24 hours after each of the first three doses. Medicines with a narrow safe dose range, such as warfarin or ciclosporin, may need additional checks. Do not adjust them yourself.

Use supportive medicines exactly as prescribed. Steroids, antihistamines or other preventive treatment depend on your own reactions and treatment plan; they should not be copied from another T-cell-engaging medicine's schedule. Check before adding herbal or “immune-boosting” products.

Discuss vaccinations with your team, taking account of your overall health, other medicines and previous cancer treatment. The vaccine plan should be individual rather than based on instructions for a different immunotherapy.

Everyday life during treatment

The first treatment phase can require more support than later treatment. Arrange help with transport, meals, children or other dependants before admission or prolonged observation. A caregiver should know the warning symptoms and where you must be assessed. Keep your treatment record accessible rather than only in an app that may be unavailable in an emergency.

Eat regularly and follow the fluid plan given by the team. Drinking large amounts is not safe for everyone with heart or kidney problems. Maintain hand hygiene, safe food preparation and distance from people with active infections. Ask your team about work and public transport if you are unwell or have additional infection risks.

Build activity gradually and avoid tasks in which sudden dizziness or loss of concentration could harm you or others. Discuss travel before booking, because proximity and observation requirements may limit plans. Tell dentists and other clinicians about the treatment before procedures. Sex can be possible if comfortable, but pregnancy prevention remains necessary, and bleeding risk or illness may require temporary adjustments.

Driving and hazardous activities

Do not drive if dizzy, faint, tired, confused or affected by a reaction or premedicine. Arrange transport after early infusions and prolonged observation. The centre should confirm when normal driving is appropriate; feeling well at the end of the short drip is not a reason to leave before observation finishes.

Fertility, contraception, pregnancy and breastfeeding

If you could become pregnant, use effective contraception during treatment and for at least one week after the last dose. US information advises against breastfeeding during treatment and for at least one week afterwards; EU information requires stopping breastfeeding during treatment. Agree a restart plan with the treating team. Pregnancy status should be checked before treatment.

Contact the team promptly if pregnancy occurs or contraception fails. Effects on future fertility are not fully known; discuss preservation options before starting, especially if other treatment can affect fertility. Restrictions for a person who can become pregnant should not automatically be applied as identical evidence-based rules for male partners. The complete regimen needs an individual plan.

After treatment finishes

Your team will arrange follow-up for any ongoing symptoms or abnormal blood tests, including liver changes. Do not stop prescribed medicines for a treatment reaction without advice. Keep a record of any significant reaction and how it was treated, and tell other clinicians that you have received tebentafusp.

Follow the agreed plan for scans, blood tests and contraception. Report persistent symptoms or new problems after treatment rather than assuming that they will settle on their own.

Frequently asked questions