Quizartinib (Vanflyta)

Quizartinib at a glance

Quizartinib, also called Vanflyta, blocks a protein called FLT3 that can drive abnormal blood-cell growth. The relevant selection test looks for a particular change called FLT3-ITD. Not every FLT3 change has the same meaning, so the exact test report matters.

The tablets are taken once daily on the days specified in your treatment calendar, with or without food. During chemotherapy they are usually taken for two weeks of a cycle. During maintenance they are taken continuously, with an initial lower dose and an increase only when the heart-rhythm assessment allows it.

Quizartinib can change the heart's electrical recovery time, called the QT interval. This can sometimes cause a dangerous rhythm or cardiac arrest. ECGs and blood tests for potassium and magnesium are essential, even if you feel well. Interacting medicines and fluid loss from vomiting or diarrhoea can increase this risk.

What quizartinib is and how it works

FLT3 is a receptor protein involved in signals that help blood cells grow. An internal tandem duplication, or ITD, is an abnormal repeated stretch of genetic material within the FLT3 gene. This can leave growth signalling overactive. Quizartinib is a tyrosine kinase inhibitor that interferes with this signal.

It is a targeted treatment rather than conventional chemotherapy. However, it is commonly given alongside chemotherapy during the earlier phases of treatment. The medicines have different jobs and overlapping side effects. A problem such as a low blood count may reflect the disease, chemotherapy, quizartinib or several factors together.

Maintenance means continuing treatment after the earlier intensive phases to help maintain disease control. It does not mean that follow-up becomes optional or that tablets should be stopped when blood results look better. Your specialist decides the sequence, duration and any changes according to your response and tolerability.

How the team decides whether it is suitable

Your haematologist considers the diagnosis, a validated FLT3-ITD test, previous treatment, fitness for the planned chemotherapy, heart history and other illnesses. The test may be performed on blood or bone marrow. A result simply saying “FLT3 positive” may need clarification because ITD and other FLT3 changes are not interchangeable.

Heart-rhythm history is especially important. Tell the team about fainting, previous ventricular arrhythmias, torsades de pointes, congenital long QT syndrome, a family history of sudden unexplained death, heart failure or significant heart disease. Also mention water tablets, recurrent diarrhoea or any condition that can lower potassium or magnesium.

US information prohibits treatment in people with severe potassium or magnesium deficiency, long QT syndrome, or a history of ventricular arrhythmias or torsades de pointes. European information lists congenital long QT syndrome among its contraindications and requires particular caution with other significant cardiac risks.

Mild or moderate liver or kidney impairment does not routinely require a dose adjustment. Severe impairment has not been adequately studied; European guidance does not recommend use in that situation. Safety and effectiveness below age 18 are not established. Individual assessment remains essential.

Before treatment starts

An ECG records the heart's electrical activity. The team measures QTcF, a QT interval adjusted for heart rate using a standard calculation. Quizartinib should not be started when QTcF is above 450 milliseconds.

Blood tests check potassium, magnesium and other electrolytes, blood counts, kidney function and liver function. Low potassium or magnesium must be corrected before treatment. Bring a complete list of medicines, including anti-sickness tablets, antibiotics, antifungals, supplements and medicines obtained elsewhere.

Your team explains the chemotherapy plan, infection prevention and any supportive medicines. Some antifungals and anti-sickness medicines can interact with quizartinib, so their use needs deliberate coordination rather than automatic discontinuation. Ask which medicines must continue and whether your quizartinib dose has been adjusted for them.

Patients who could become pregnant need a pregnancy test within seven days before starting. Discuss contraception, breastfeeding and fertility preservation before treatment where feasible. Obtain the hospital's urgent advice details, written temperature instructions and a treatment calendar showing exactly when each dose starts and stops.

How treatment is taken

Understanding the three treatment phases

Induction is the early phase intended to bring the leukaemia under control. In the usual first induction schedule, quizartinib is 35.4 mg once daily on days 8–21. A particular second induction schedule starts it on day 6 and continues through day 19. The chemotherapy dates therefore matter when interpreting your tablet calendar.

Consolidation follows a response to induction and aims to strengthen disease control. Quizartinib is usually 35.4 mg once daily on days 6–19 of each consolidation cycle. The reviewed regimen allows up to two induction cycles and up to four consolidation cycles, but not everyone receives the maximum. Your team decides when blood-count recovery and clinical circumstances allow the next phase.

Maintenance begins at 26.5 mg once daily for the first 14 days. The usual increase is to 53 mg daily from day 15, only if QTcF is 450 milliseconds or less and the individual safety assessment permits it. A significant earlier QT problem can mean staying at the lower dose. Do not increase merely because day 15 has arrived.

Maintenance is taken every day without a routine break between 28-day cycles, for up to 36 cycles unless disease progression, side effects or another clinical decision changes the plan. Earlier two-week schedules must not be carried over into maintenance by mistake. Equally, maintenance instructions must not be used during an induction cycle.

Tablets, food and the decimal strengths

Take the prescribed dose at approximately the same time each day, with or without food. Swallow tablets whole; do not cut, crush or chew them. Available strengths are 17.7 mg and 26.5 mg. For example, 35.4 mg is two 17.7 mg tablets, while 53 mg is two 26.5 mg tablets. These strengths are not rounded to the nearest whole number.

Older research reports may describe doses using the salt form rather than the amount of quizartinib itself. Do not use those figures to recalculate your prescription. Confirm the tablet count whenever the treatment phase or another medicine changes. If swallowing is difficult or a feeding tube is needed, seek a pharmacy plan instead of preparing a homemade liquid.

Missed or vomited doses

If you forget a dose, take it as soon as possible on the same day and return to the usual time the following day. Do not take two doses on one day. If you only realise the next day, do not add yesterday's tablets.

If you vomit after taking the dose, do not take a replacement. Take the next scheduled dose at the usual time the following day. Repeated vomiting or diarrhoea needs prompt advice because it can lower potassium or magnesium and increase heart-rhythm risk.

If you take more tablets than prescribed, contact the treating hospital or emergency department immediately, even if you feel well. Bring the pack and the amount and time taken.

Keep tablets in their original labelled packaging, away from children, and follow the pack storage instructions. US guidance is 20–25°C (68–77°F) with permitted excursions to 15–30°C (59–86°F); European information requires no special storage conditions. Return unwanted tablets to the pharmacy.

Around a stem-cell transplant

Quizartinib should be stopped seven days before the transplant conditioning regimen begins. The transplant team must give you the exact date; conditioning is the preparatory treatment, not the transplant day itself.

Post-transplant instructions differ. US information does not include maintenance after an allogeneic transplant, because an overall-survival benefit in that setting has not been demonstrated. European information allows a specialist-directed restart in selected patients after blood-count recovery and assessment of graft-versus-host disease (a reaction in which donor immune cells attack body tissues) and its treatment. Do not assume that a pre-transplant prescription automatically resumes afterwards.

Monitoring during treatment

During induction and consolidation, ECGs are performed before treatment and at least weekly while taking quizartinib, with additional checks when needed. During maintenance, ECGs are checked before starting and weekly for the first month after starting and after dose escalation (at least a month in the US wording), then according to clinical need.

Extra ECGs may be needed with a QT-prolonging medicine, significant vomiting or diarrhoea, or another risk factor. Potassium and magnesium are monitored and maintained within the normal range. A severe fall can require quizartinib to be withheld while the problem is corrected; supplements alone are not always enough to make the next dose safe.

Blood counts show whether white cells, platelets and red cells are recovering. Persistent severe low counts after remission may require a lower dose and further bone marrow assessment. Liver tests, kidney tests and other blood chemistry help the team identify treatment effects and adjust supportive care.

Blood and bone marrow assessments also evaluate response. The timing depends on the treatment phase. Ask what your response results mean and when the next phase can begin. A delay for safety does not automatically mean that the medicine has stopped working.

Common side effects and practical care

Low blood counts and infection

The overall treatment programme can markedly reduce blood cells. Low neutrophils, a type of white cell, increase infection risk. Fever during a low count can be an emergency. Low red cells can cause tiredness and breathlessness, while low platelets can cause bruising, nosebleeds or bleeding gums.

Wash your hands regularly, follow the team's food and infection-prevention advice, and report symptoms early. Take prescribed preventive medicines as directed. Do not start an antibiotic left over at home: it may be unsuitable for the infection and may interact with quizartinib. Transfusions or other support may be needed according to blood results.

Nausea, vomiting and diarrhoea

Use the anti-sickness medicine selected by your team. Some familiar antiemetics can prolong QT, so adding an over-the-counter or previously prescribed medicine without checking is unsafe. Small meals and regular sips may help, within any fluid restriction.

Follow the written diarrhoea plan and record changes from your usual bowel pattern. Call promptly for persistent symptoms, dizziness, reduced urine, blood in the stool or difficulty drinking. Fluid and mineral replacement may need hospital treatment, particularly when heart-rhythm risk is increased.

Mouth soreness, appetite and abdominal discomfort

Mouth ulcers or inflammation can make eating painful. Use a soft toothbrush and gentle mouth care; ask which rinses and pain treatments are suitable. Report white patches, bleeding or pain that prevents drinking. A dietitian can help when appetite or weight falls.

Mild digestive discomfort can occur, but severe or persistent abdominal pain needs assessment. Do not assume it is an expected side effect when there is fever, vomiting, a swollen abdomen or blood in the stool. Your team must consider infection and other causes related to the complete regimen.

Headache, tiredness and sleep

Headache and sleep disturbance may occur, and the full treatment programme can be exhausting. Balance gentle movement with rest and accept help with practical tasks. Check pain medicines with the pharmacist because bleeding risk, liver function and interactions can affect the safest choice.

A sudden major change in energy, faintness, palpitations or breathlessness should not be dismissed as fatigue. These symptoms can reflect anaemia, infection, an electrolyte problem or a heart-rhythm disturbance. Contact the team promptly.

Important risks to understand

QT prolongation and dangerous heart rhythms

QT prolongation means that part of the heart's electrical recovery is taking longer than expected. You may have no warning symptoms, which is why ECG monitoring is necessary. A prolonged QT interval can sometimes lead to torsades de pointes, a dangerous rhythm that may cause collapse or cardiac arrest.

Seek emergency care for fainting, collapse, a seizure, or a racing or irregular heartbeat with dizziness, weakness, chest pain or breathlessness. Do not drive yourself. Tell clinicians you take quizartinib and show your medication list or patient safety card if available.

The team may reduce the dose, interrupt treatment or stop it permanently depending on ECG findings and symptoms. Life-threatening arrhythmia and recurrent severe QT prolongation despite correction of risk factors require permanent discontinuation under the prescribing guidance. Do not restart after a heart-related pause without explicit instructions.

Electrolyte disturbances

Potassium and magnesium help the heart and nerves function normally. Low levels may cause weakness, cramps or palpitations, but can also be silent. Vomiting, diarrhoea and some medicines increase the risk. Other minerals, including calcium and phosphate, can also fall during treatment.

Take supplements only as prescribed. Eating a particular food or drinking a sports drink does not reliably correct a severe deficiency. The team may arrange intravenous replacement, repeat blood tests and another ECG before deciding that treatment can resume.

Serious infection and bleeding

Sepsis is a serious whole-body response to infection and requires urgent treatment. Report fever, shaking chills, confusion, sudden weakness, a new cough, breathlessness or feeling very unwell, even without fever. European information highlights particular vigilance for severe infection in people older than 65 during induction.

Seek immediate help for uncontrolled bleeding, vomiting blood, black stools, or a severe headache after a fall. New bruising or smaller bleeds should also be reported because platelets may be low. Do not start aspirin or anti-inflammatory medicines without the team's advice.

Liver changes and unusual inflammatory reactions

Liver blood tests can become abnormal during the treatment programme. Report yellow skin or eyes, dark urine, marked nausea or right-sided upper abdominal pain. Keep monitoring appointments even without symptoms.

US information also records differentiation syndrome and an inflammatory skin condition called Sweet syndrome from other quizartinib studies in a different treatment setting. Their reported percentages should not be applied to the routine regimen described here. Fever with new breathing difficulty, rapid swelling or weight gain, or a painful raised rash needs urgent assessment; infection and other causes must also be considered.

Other medicines, supplements and vaccinations

Quizartinib is processed through an enzyme called CYP3A. Strong inhibitors, including some antifungals and antibiotics, can raise drug exposure and require a prescribed quizartinib dose reduction. Strong or moderate inducers, including rifampicin, some seizure medicines and St John's wort, can reduce exposure and should be avoided.

Medicines that prolong QT can add to the rhythm risk. These include some anti-sickness medicines, antibiotics, antifungals and transplant medicines. Sometimes an interacting treatment is necessary; the team may alter doses and increase ECG monitoring. Do not stop prescribed infection prevention or transplant medicines yourself.

The April 2026 US information also advises avoiding medicines transported by a protein called BCRP where possible, because quizartinib may increase their side effects. If unavoidable, closer monitoring and a reduction in the other medicine may be needed. European information advises caution and consideration of such reductions. Give the pharmacist your complete list, including cholesterol medicines and supplements, rather than trying to identify these interactions yourself.

Check heartburn medicines and food or herbal products with the pharmacist. A studied proton-pump inhibitor, lansoprazole, did not meaningfully change quizartinib exposure, so the fasting and acid-treatment rules for other TKIs should not be copied onto this medicine.

Ask the team about vaccination timing. Live vaccines should not be given while the immune system is significantly weakened unless the specialist confirms an appropriate plan. Non-live vaccines may still be useful, but response and timing depend on chemotherapy, blood counts and transplantation.

Everyday life during treatment

Use the current written calendar and check it after every treatment review. Mark both tablet days and planned breaks during chemotherapy. During maintenance, confirm that the dose increase has actually been authorised.

Work, exercise and travel depend on blood counts, symptoms and the need for frequent checks. Avoid driving if dizzy, weak, faint or otherwise unwell. Do not drive yourself for assessment of possible rhythm symptoms. Arrange travel only after discussing access to tests and urgent care.

Follow the team's advice about food safety, mouth care and contact with people who have infections. Tell your dentist about the treatment before any procedure. There is no single fluid target for everyone; ask for a plan if you have heart or kidney problems or a fluid restriction.

Tell the team if treatment affects your mood, relationships or sleep. Practical and emotional support is part of care.

Pregnancy, breastfeeding and fertility

Quizartinib can harm an unborn baby. Patients who could become pregnant should use effective contraception during treatment and for at least seven months after the last dose. Men with female partners who could become pregnant should use effective contraception during treatment and for at least four months afterwards.

Report pregnancy or a suspected pregnancy promptly. Ask the team which contraceptive method is suitable, and whether another medicine in the regimen requires longer precautions. A quizartinib interval must not shorten the precautions needed for chemotherapy or transplant treatment.

Do not breastfeed while taking quizartinib. US information specifies one month after the final dose; European information specifies at least five weeks. Agree the restart date with the team for your product and full treatment plan.

Animal studies suggest effects on male and female reproductive organs and fertility. This does not establish an individual's fertility outcome or guarantee recovery in people. Discuss fertility preservation before treatment where possible, particularly because accompanying chemotherapy can also affect fertility.

After treatment stops

Follow-up continues according to the reason treatment ended, your response and any next treatment. Blood counts, ECGs, electrolytes and organ tests may still be needed, especially if a side effect caused the stop. Follow the team's instructions rather than assuming every risk ends with the final tablet.

Continue the contraception and breastfeeding precautions for the full specified periods. Keep a record of a serious rhythm event or interacting medicine, and return unused tablets to the pharmacy.

Frequently asked questions