Tarlatamab (Imdelltra / Imdylltra)

Tarlatamab at a glance

Tarlatamab is an immunotherapy given through a drip into a vein for certain adults with extensive-stage small cell lung cancer after platinum-based chemotherapy. Brand names include Imdelltra and Imdylltra in different markets.

The first dose is smaller than later doses. Early visits require planned observation, and you will need a caregiver and arrangements to stay near suitable emergency care. This is part of treatment, not an optional extra. Keep your treatment alert card and urgent oncology number with you.

How tarlatamab works

Tarlatamab is a bispecific T-cell engager: one part attaches to a protein called DLL3 on cancer cells, while another attaches to CD3 on immune T cells. Bringing them together helps the immune cells attack the cancer.

It is different from PD-1 or PD-L1 checkpoint inhibitors. Strong immune activation can cause cytokine release syndrome (CRS), and treatment can also affect the brain and nervous system. These risks explain the smaller first dose, preventive medicines and observation plan.

How your team decides whether it is suitable

Tarlatamab is used for extensive-stage small cell lung cancer that has progressed during or after platinum-based chemotherapy. It is not automatically a treatment for non-small cell lung cancer or every tumour that has DLL3.

Your oncologist considers previous treatment, current symptoms, other illnesses, organ function and whether the monitoring and emergency-care arrangements can be met. Discuss any brain metastases, neurological symptoms, infection or previous severe treatment reaction.

The product indications reviewed do not require a routine positive PD-L1, MSI or TMB result, or a specified DLL3 test result, before treatment. Your team may still request tests to clarify the diagnosis or other treatment options.

Before treatment starts

Your team will review medicines, allergies, previous treatment, infections and any neurological problems. Tell them about pregnancy, breastfeeding and any possibility of pregnancy. Bring all prescribed, over-the-counter and herbal medicines to the medication review.

Blood tests check blood-cell counts, liver function and other measures such as electrolytes. The team may assess your usual memory, speech, movement and alertness so changes can be recognised. A caregiver who knows you well can help notice subtle differences.

Before the first dose, agree the observation schedule, transport, where you will stay and who will be with you. Ask which hospital can assess CRS or neurological symptoms at any hour. If these arrangements are difficult, tell the team before treatment rather than trying to manage alone.

How treatment is given

A smaller first dose

The usual schedule starts with 1 mg on day 1, followed by 10 mg on days 8 and 15, then 10 mg every two weeks. Each dose is infused over about one hour. The smaller starting dose helps reduce the risk of CRS.

Preventive treatment around the first two doses includes a corticosteroid and intravenous fluids according to the prescribing protocol. Your team adjusts fluid arrangements to your health. These medicines do not remove the need for observation.

Observation and staying near care

Current US and European instructions reviewed call for monitoring in a healthcare setting for 6–8 hours from the start of the day 1 and day 8 infusions. Longer observation or hospital admission may be needed if symptoms occur.

The instructions after leaving the unit differ. The US label recommends staying within one hour of appropriate healthcare for a total of 48 hours from the start of each of those two infusions, with a caregiver, and an assessment including vital signs the following day. The European label specifies staying near a healthcare facility with a caregiver for 24 hours from each of those infusions. Your team must give you the plan for the product and protocol being used; do not choose the shorter period yourself.

Later visits also need a monitoring plan. Its duration depends on the product instructions and any earlier CRS or neurological reaction. Do not assume that a one-hour infusion means a one-hour appointment or that tolerating the first doses removes all risk.

If a dose is delayed

Contact the unit if you miss treatment. After a longer interruption, a smaller restart dose, preventive medicines or extra monitoring may be required. The team must calculate the restart plan; do not simply resume your previous schedule elsewhere.

Monitoring and checking whether treatment is working

Staff check symptoms and vital signs and look for early CRS, infection and neurological changes. Blood tests monitor blood counts, liver function and other results that may change during treatment. Current US instructions check blood counts, liver enzymes and bilirubin before every dose through cycle five, then before day one of each cycle from cycle six; your team may check more often. Tests remain necessary even when you feel well.

Tell the team about subtle changes in speech, handwriting, memory, walking or alertness. Caregivers should report changes rather than waiting for the patient to recognise them.

Scans and clinical review assess the cancer response. Side-effect intensity does not show whether treatment is working. Treatment may be withheld or stopped for a serious reaction; the team balances cancer control with recovery and the risk of another reaction.

Common side effects and how to manage them

Commonly reported effects include CRS, tiredness, reduced appetite, altered taste, fever, constipation, muscle or bone pain and nausea. Low blood counts and changes in blood salts or liver tests can also occur. Common does not mean harmless: fever or a change in alertness always needs attention.

Appetite and taste changes

Try small meals and foods that remain appealing, and ask for dietetic help if weight is falling. Use prescribed anti-sickness medicines. Contact the team if you cannot keep fluids down.

Tiredness and discomfort

Pace activities and accept help around treatment days. Gentle activity may help when you are well, but new marked weakness or dizziness needs assessment. Ask which pain relief is safe with your medicines.

Constipation

Discuss constipation early. Fluids, suitable activity and a prescribed laxative may help. Severe pain, persistent vomiting or a swollen abdomen needs urgent advice.

Less common but important side effects

Cytokine release syndrome (CRS)

CRS is an inflammatory reaction caused by activated immune cells releasing signalling proteins. It can cause fever, chills, a fast heartbeat, dizziness, low blood pressure and breathing difficulty. Severe reactions can be life-threatening. It is more likely around early doses but can occur later.

Report symptoms immediately, including after leaving the unit. Do not assume fever is an expected effect that can be managed at home. Infection can look similar and also needs assessment. Treatment may include oxygen, fluids, corticosteroids, a medicine such as tocilizumab and hospital care.

Brain and nervous-system effects

A reaction called immune effector cell-associated neurotoxicity syndrome (ICANS) can cause confusion, difficulty speaking or writing, unusual sleepiness, altered behaviour or seizures. Other neurological problems can include weakness, poor balance or numbness. These may occur with CRS or separately, and may start after the initial observation period.

A caregiver may notice changes first. Seek urgent help and tell staff that you are receiving a T-cell-engaging medicine. Severe confusion, a seizure, reduced consciousness or new major weakness is an emergency.

Infection and low blood counts

Low white blood cells can increase infection risk. Anaemia may cause fatigue or breathlessness; low platelets can cause bruising or bleeding. Report fever, chills, unusual bleeding, painful urination or a new cough promptly. Do not wait for a high temperature if you feel seriously unwell.

Liver problems and allergic reactions

Liver irritation may first appear on blood tests. Report yellow skin or eyes, dark urine or upper abdominal pain. During the infusion, tell staff immediately about rash, swelling, wheezing or faintness. Severe allergy needs emergency treatment.

Other medicines, supplements and vaccinations

Have all medicines checked by your oncology pharmacist. The temporary inflammation caused by tarlatamab can change how the body handles some other drugs, especially around the first doses or during CRS. Medicines with a narrow safe dose range may need additional monitoring.

Do not start herbal products, supplements or leftover steroids without advice. Preventive steroids and steroids used to treat a reaction are part of safe care when prescribed; do not omit them because this is immunotherapy.

Ask the team about vaccinations and timing. Your blood counts, previous treatments and any immune-suppressing medicines affect the advice. Do not arrange a live vaccine without specialist approval.

Everyday life during treatment

Plan transport and caregiver support for the early treatment period. Keep a charged phone, the treatment alert card and the urgent contact number available. Avoid travel away from the agreed healthcare area during the required observation period.

Do not drive, operate machinery or undertake hazardous activities if you have any neurological symptoms. Wait until symptoms have resolved and discuss a safe return with your team. Arrange someone else to drive you home from treatment.

Eat regularly, drink according to your team’s advice and balance rest with gentle activity. Report weight loss or persistent difficulty eating. Wash hands and avoid close contact with people who are unwell; your team can advise on additional precautions if blood counts are low.

Work and family routines may need adjustment because observation and follow-up take time. Ask for practical help before treatment starts rather than trying to fit a full working day around an early infusion.

Fertility, contraception, pregnancy and breastfeeding

Tarlatamab may harm a developing baby. Pregnancy status should be checked before treatment when relevant. If you could become pregnant, use effective contraception during treatment and for 2 months after the last dose. Tell the team promptly about pregnancy, suspected pregnancy or contraceptive failure.

Do not breastfeed during treatment or for at least 2 months after the final dose. The effects on future fertility are not known; discuss fertility preservation before treatment if relevant. Previous or accompanying medicines may require different precautions.

After treatment finishes

Keep attending the planned follow-up and blood tests. Continue to report new neurological symptoms, infection symptoms or other concerns after treatment stops, and tell other clinicians that you have received tarlatamab.

Your team will explain when extra caregiver or travel restrictions can end. Continue pregnancy and breastfeeding precautions for the stated period after the final dose. If treatment restarts after an interruption, the restart dose and observation arrangements must be reassessed.

Frequently asked questions