Larotrectinib (Vitrakvi)

Larotrectinib at a glance

Vitrakvi is a verified brand of larotrectinib. It blocks proteins called TRK that can drive cancer growth when an NTRK gene becomes abnormally joined to another gene. This joining is called a gene fusion. The treatment decision depends on the precise molecular result and the wider clinical situation.

Larotrectinib is usually taken twice daily and can be taken with or without food. It is available as 25 mg and 100 mg capsules and a 20 mg/mL oral solution. Capsules and liquid can provide equivalent treatment when the pharmacist confirms the correct dose. They have different handling and storage instructions.

Important risks include effects on thinking, balance, mood and sleep; liver injury; and bone fractures. Digestive symptoms, tiredness and changes in blood counts also occur. Targeted treatment still needs regular monitoring, even when symptoms improve.

What larotrectinib is and how it works

The NTRK1, NTRK2 and NTRK3 genes normally help make TRK proteins involved in nerve-cell signalling. An NTRK fusion can produce an abnormal protein that sends persistent growth signals. Larotrectinib inhibits TRK activity and can reduce the growth and survival of cells relying on that signal.

You may hear this called a tumour-agnostic or histology-independent treatment. These terms mean that a particular molecular feature helps guide the choice across cancers arising in different places. They do not mean the medicine works for every cancer, or that the tumour's location and other characteristics no longer matter.

Larotrectinib is a tyrosine kinase inhibitor, not a checkpoint immunotherapy or conventional chemotherapy. TRK proteins also have normal roles in the body, which helps explain why a selective drug can still cause neurological effects. Benefits and adverse effects vary between individuals.

How the team decides whether it is suitable

The key result is an NTRK gene fusion. A report mentioning NTRK expression, a mutation or extra copies of a gene does not automatically establish the same finding. Ask the team to explain exactly what was detected and whether it supports treatment. The US label also specifies the absence of a known acquired resistance mutation.

European information requires confirmation using a validated tumour test. The US label allows specialists to consider exceptions to confirmation in a few characteristic tumour settings. This is a specialist decision, not a reason to assume that testing is unnecessary. The pathology and molecular reports should be interpreted together.

The team considers the likely benefit, other suitable options, previous treatment and your general health. A fusion result cannot guarantee a response or predict exactly how long benefit will last. If treatment stops helping, further molecular assessment may help explain resistance and guide the next discussion.

Tell the team about liver disease, balance or memory problems, previous fractures, falls, allergies and difficulty swallowing. Moderate or severe liver impairment usually requires a lower starting dose. Kidney impairment does not automatically require a dose reduction under the reviewed labels, but still matters to overall care.

Before treatment starts

You will usually have a full blood count and tests of liver and kidney function. Liver assessment includes enzymes such as ALT and AST, alkaline phosphatase and bilirubin. These provide a baseline for detecting treatment-related changes. Your team may also check blood salts and other tests according to your health and symptoms.

Explain any existing dizziness, falls, sleep problems, mood changes or difficulty concentrating. A caregiver's observations can be useful if memory or behaviour is affected. For a child, the team should know their usual activity, walking, feeding and development so that new changes can be recognised.

Discuss past bone injuries, osteoporosis or pain that limits movement. The team may investigate an existing concern before treatment; the labels do not set one universal bone-scan schedule for everyone. Pregnancy status should be checked in patients who could become pregnant.

Bring prescriptions, non-prescription medicines, supplements and herbal remedies to the medication review. Mention previous hepatitis or other important infections; any additional screening or prevention is individualised. Ask for a written dose, contact number, blood-test timetable and instructions for missed doses and illness.

How treatment is taken

Dose and daily routine

The usual adult dose is 100 mg twice daily. Children's doses depend on body surface area, which is calculated from height and weight, and on age and the applicable product information. Current European guidance has a lower starting dose for babies under three months. Never calculate an infant's dose from an adult capsule or another child's prescription.

Take each dose at the prescribed times, with or without food. An alarm or medicine diary can help. Treatment generally continues while it benefits you and adverse effects remain acceptable. There is no routine self-selected week off. A lower dose or temporary hold may be needed, with clear instructions about when to restart.

Capsules and oral solution

Swallow capsules whole with water. Do not open, chew or crush them. If swallowing is difficult, ask about the manufactured oral solution; do not make a homemade liquid by emptying capsules into food or a drink. Switching formulation requires confirmation of both milligrams and the liquid volume in millilitres.

The solution contains 20 mg in each mL. The pharmacist should demonstrate the correct oral syringe and bottle adapter. Use the prescribed volume, remove air bubbles and check the measurement at eye level. A kitchen teaspoon is not accurate enough. Give the liquid slowly towards the inside of the cheek, allowing time to swallow.

For a child, follow the demonstrated position and keep them upright for a few minutes after the dose. US instructions say not to give another dose if the child spits it up or you are unsure the whole amount was swallowed; wait until the next scheduled dose. Report repeated difficulty so the team can help.

Keep the adapter in the bottle and replace its cap. Clean and dry the syringe as the supplied instructions describe. US instructions use warm water, advise against boiling and replace the syringe after seven days or sooner if damaged or unreadable. Do not borrow another medicine's syringe-cleaning rules.

European information permits the solution through a suitable nasogastric tube. Feeding is paused and the tube flushed before and after the dose. The solution must not be mixed with feeding formula. Flush volumes need adjustment for newborns and fluid-restricted children, so obtain an individual tube plan rather than improvising.

Missed or vomited doses

Missed-dose guidance differs. European information says to skip the missed dose and take the next at its scheduled time. US information says to take it when remembered, unless the next dose is due within six hours; then skip it. Follow the written plan for your product; if timing is unclear, call the pharmacist. Never double up.

After vomiting, do not take a replacement dose. Take the next dose at the usual time unless the team advises a hold. Repeated vomiting or an inability to retain fluids needs prompt advice. If too much medicine is taken, contact the treating team or emergency service straight away.

Storage and opened bottles

Keep capsules in their original packaging at the temperature on the label. The oral solution needs refrigeration at 2°C–8°C (35.6–46.4°F) and must not be frozen. Write the opening date on each bottle and ask the pharmacist to write its discard date. Keep all medicine away from children.

Do not assume every Vitrakvi liquid has the same opened-bottle life. Current European information specifies ten days. The reviewed US label specifies 90 days for a 100 mL bottle and 31 days for a 50 mL bottle. Follow the exact dispensed product's instructions; check before using a bottle beyond its stated limit.

Monitoring and checking whether treatment is working

Liver tests need particular attention. US information advises testing before treatment, every two weeks for the first two months and monthly afterwards. European information advises every two weeks in the first month, monthly for the next six months and periodically afterwards. Abnormal results can require more frequent checks under either approach. Your team should provide your actual timetable.

Blood counts help identify anaemia and low infection-fighting cells. Kidney function and blood salts may also be checked. Tell the team about changes in balance, thinking, mood, sleep, appetite and movement at each visit. Monitoring cannot rely only on blood tests because some important effects are recognised through symptoms.

For children, weight and height affect dosing and should be reassessed as directed. Tell the team about reduced activity, unusual irritability, a new limp or altered feeding. Growth and developmental follow-up depend on age and the wider treatment plan; do not adjust the volume yourself when your child gains weight.

Response is assessed through symptoms, examination and appropriate scans. Feeling better is encouraging but does not replace planned assessments. Likewise, a treatment pause does not necessarily mean it has failed: the team may be allowing recovery before resuming at a safer dose.

Common side effects and practical management

Digestive symptoms

Nausea, vomiting, diarrhoea and constipation can occur. Use prescribed supportive medicines and report symptoms that interfere with eating, drinking or taking treatment. Small meals and regular sips may help. Follow any heart or kidney fluid restriction rather than forcing large amounts of water.

Keep a record of loose stools and urine output. Persistent diarrhoea, dizziness on standing or less urine can signal dehydration. Fever, blood in stools or severe abdominal pain makes assessment more urgent. Constipation with vomiting or marked abdominal swelling also needs prompt advice.

Tiredness and blood-count changes

Balance gentle activity with rest, and ask for help with demanding tasks. Increasing tiredness can reflect anaemia, infection, dehydration or disturbed sleep. Report breathlessness, marked weakness or paleness so the team can decide whether tests or supportive treatment are needed.

Lower white-cell counts can increase infection risk. Fever, chills, a new cough, painful urination or feeling suddenly unwell needs immediate contact with the team. Follow your hospital's temperature threshold; do not wait for a high temperature if you are deteriorating.

Muscle pain, skin and weight changes

Muscle aches and discomfort can occur, but persistent focal bone pain or a new limp should not simply be treated as an ordinary ache. Ask which painkillers are suitable, because interactions and liver function may affect the choice.

Use gentle skin care for rash and report worsening symptoms. Rapidly spreading rash, blistering, mouth sores or facial swelling needs urgent assessment. Report weight gain or swelling too, especially if rapid or accompanied by breathlessness. Weight changes may have several causes and deserve review.

Less common but important side effects

Effects on the brain, nerves and mood

Dizziness, tingling, changes in walking, confusion, memory or concentration problems, altered mood and disturbed sleep can occur. A family member may notice changes before you do. Tell the team rather than assuming these symptoms are an unavoidable part of cancer treatment.

Neurological effects often start early, but some can appear after many months. Do not assume the risk has passed after the first few weeks. The team may hold treatment, reduce the dose or stop it, depending on severity and recovery. Do not drive or use hazardous machinery while affected.

New marked confusion, hallucinations, inability to walk safely or unusual difficulty waking needs urgent assessment. A seizure, collapse, sudden one-sided weakness or speech difficulty is an emergency. Mood symptoms deserve attention too; thoughts of harming yourself require immediate support from emergency or mental-health services.

Liver injury

Liver enzymes can rise without symptoms, which is why scheduled tests matter. Yellow eyes or skin, dark urine, pain in the upper right abdomen, persistent nausea or unusually severe fatigue can indicate liver injury. Contact the team promptly and do not wait for the next blood-test appointment.

Mild abnormalities and serious injury are managed differently. Treatment may be paused, reduced or permanently stopped. Certain combinations of raised liver enzymes and bilirubin require permanent discontinuation under US guidance; European guidance also sets strict interruption and restart conditions. These decisions need specialist interpretation, not self-adjustment from a laboratory result.

Bone fractures

Fractures have occurred in adults and children receiving larotrectinib, sometimes after relatively minor injury. Some involved bones affected by cancer. New localised pain, swelling, a deformity, a limp or difficulty bearing weight should be assessed promptly. A young child may show this by refusing to use an arm or leg.

Avoid pushing through suspected fracture pain or relying on repeated painkillers to continue normal activity. The team may arrange imaging and appropriate treatment. It is not known exactly how larotrectinib affects healing of an existing fracture or future fracture risk, so ask for an individual activity and follow-up plan.

Other medicines, supplements and vaccinations

Larotrectinib is affected by the CYP3A enzyme system. Some antifungals, antibiotics, antiviral medicines and seizure treatments can substantially change its level. It can also affect other medicines. Check every new prescription, short course, supplement and non-prescription product with the oncology pharmacist.

Avoid grapefruit and grapefruit juice, and do not take St John's wort. Strong CYP3A inhibitors are generally avoided or require a specialist dose reduction. Moderate inhibitors can require closer monitoring. Never halve the dose yourself just because a medicine appears on an interaction list.

Strong enzyme inducers are avoided where possible. European information also advises avoiding moderate inducers; US information provides a clinician-managed dose increase when certain combinations are necessary. These are different prescribing approaches, not instructions to double your own dose. Adjustments when an interacting medicine stops also need supervision.

Larotrectinib may increase exposure to some sensitive medicines, including certain sedatives or transplant medicines. European information also notes possible interactions with other enzyme and transporter pathways. A complete medication review is more useful than relying on a short list of examples.

Discuss vaccinations with the team. Non-live vaccines may be appropriate, though their effectiveness can be reduced during cancer treatment. Avoid live vaccines unless the specialist has confirmed they are suitable. Timing after treatment depends on immune recovery and the overall plan rather than one universal waiting period.

Everyday life and planned procedures

Do not drive or operate machinery until you know how treatment affects you. Be cautious with ladders, cooking over open flames and other activities where dizziness could cause injury. Keep walkways clear and use support if unsteady. Report falls even if you believe they were minor, particularly when new pain follows.

Tell your dentist, surgeon and anaesthetist about larotrectinib and your recent blood results. There is no universal surgical stopping interval in the reviewed product information. Your clinicians should agree any pause according to the procedure, oral intake, interacting medicines and your clinical condition.

Plan travel around medicine supplies, appointments and refrigeration for the liquid. Ask the pharmacist what to do after a temperature excursion; do not freeze the bottle in an attempt to keep it cold. Carry the prescription and urgent contact details.

For school or work, consider adjustments if fatigue, concentration or balance is affected. A simple symptom and dose diary helps conversations with the team. Caregivers should know the prescribed volume and who is responsible for giving each dose to avoid accidental duplication.

Fertility, contraception, pregnancy and breastfeeding

Larotrectinib may harm a developing baby. Pregnancy should be avoided during treatment, and suspected pregnancy should be reported promptly. US guidance specifies effective contraception during treatment and for one week afterwards for patients who could become pregnant and males with partners who could become pregnant.

European guidance specifies highly effective contraception during treatment and for at least one month afterwards for both groups. It also advises an additional barrier method when systemic hormonal contraception is used, because reduced contraceptive effectiveness cannot be excluded. Obtain a written plan rather than choosing the shortest interval from different sources.

Do not breastfeed during treatment. US guidance continues the restriction for one week after the last dose; European guidance specifies three days. Confirm the applicable interval before restarting, including any longer requirement from another medicine.

Human fertility effects are uncertain. US information describes a possible reduction in female fertility based on animal findings; this does not mean infertility is inevitable. Discuss fertility preservation before starting if future parenthood matters to you or your child.

After treatment finishes

A temporary hold needs a clear review and restart plan. Continue symptom monitoring and any requested blood tests, especially after liver abnormalities or neurological effects. Do not restart leftover medicine at the old dose after a long interruption without checking with the team.

Continue contraception, breastfeeding restrictions and fracture follow-up for the agreed periods. If the cancer has stopped responding, ask what the next assessment will involve and whether further testing could inform the next treatment discussion. Return unused medicine through the pharmacy rather than sharing it with anyone else.

Frequently asked questions