Lazertinib (Lazcluze; Leclaza)

Lazertinib at a glance

Lazertinib blocks abnormal epidermal growth factor receptor, or EGFR, signalling. Lazcluze is the brand in the reviewed US and European prescribing information; Leclaza is another verified brand name. Brand recognition does not mean that a different product's prescription or treatment plan can be substituted automatically.

Lazcluze comes in 80 mg and 240 mg tablets. The usual starting amount is 240 mg once daily, with or without food. The reviewed Lazcluze treatment plan combines it with amivantamab, an antibody medicine given by a healthcare professional.

Important concerns with this combination include blood clots, lung inflammation, skin and nail problems, liver injury and eye problems. Some common difficulties are diarrhoea, mouth soreness, tiredness, swelling, muscle or joint pain and tingling. The risk and management depend on the whole treatment, not only the tablets.

What lazertinib is and how it works

EGFR is a protein that helps regulate cell growth. Certain changes in its gene can keep growth signals switched on. Lazertinib is a tyrosine kinase inhibitor, or TKI: it blocks the signalling part of susceptible abnormal EGFR inside the cell. This can help slow or stop the growth of cancer that relies on those signals.

Amivantamab works differently. It attaches to EGFR and MET proteins on the outside of cells and can recruit immune mechanisms against cancer cells. The two medicines therefore act in complementary ways, but they also require coordinated monitoring and supportive treatment. Lazertinib itself is not an antibody or a checkpoint immunotherapy.

A targeted mechanism does not guarantee benefit or mean treatment will be mild. Your team checks whether treatment is helping through symptoms, examinations and appropriate imaging.

How the team decides whether it is suitable

The specialist checks the precise EGFR result, rather than relying simply on the phrase “EGFR positive”. The Lazcluze combination described in the reviewed labels requires an EGFR exon 19 deletion or exon 21 L858R substitution. These are particular gene changes, not just the presence of EGFR on cells.

Testing can use tumour tissue or a blood sample looking for tumour DNA in plasma. A negative plasma test may miss a mutation, so tissue testing should follow when suitable material is available. The team also considers the diagnosis, previous treatment, general health, organ function and applicable prescribing information.

Tell the specialist about previous lung inflammation, radiation-related breathing problems, blood clots, bleeding, liver disease, kidney disease or significant eye problems. These may change the safety assessment and support needed. Evidence is limited in some severe organ impairments, and paediatric safety and effectiveness are not established in the US label.

Before treatment starts

Baseline blood tests usually include a full blood count, kidney function, liver tests, albumin and electrolytes. Albumin is a blood protein; low levels can contribute to swelling. The April 2026 US Lazcluze information specifically requires liver-function testing before treatment and during treatment as clinically indicated.

Bring a list of every medicine, supplement and herbal product, including occasional painkillers and any existing blood thinner. Your team will assess clotting and bleeding risk and arrange preventive anticoagulation when starting the combination. Never add aspirin or another blood thinner on your own.

Have the skin-prevention plan ready before the first dose. Ask which antibiotic, moisturiser, hand-and-foot wash and sunscreen to use, and what to do if a product irritates your skin. Mention antibiotic or antiseptic allergies. Preventing rash is easier than waiting until it has become painful or infected.

Discuss pregnancy testing, contraception, breastfeeding and fertility preservation before treatment. Tell the team about existing cough, breathlessness or visual symptoms so changes can be recognised. Check how to contact your treating hospital's urgent advice service outside normal hours.

How treatment is taken

Tablets and daily routine

The usual starting dose is 240 mg once daily. A specialist may reduce this to 160 mg or 80 mg daily because of adverse effects. The 160 mg dose uses two 80 mg tablets; do not split a 240 mg tablet to make a lower dose. Take only the strength and number on your current prescription.

Take lazertinib at about the same time each day, with or without food, and swallow tablets whole with water. Do not crush, split or chew them. When lazertinib and amivantamab are due on the same day, take lazertinib before the infusion or injection, following the clinic's timing instructions.

Keep taking the tablets on days without an amivantamab appointment unless the team has instructed a pause. Treatment generally continues while it helps and remains tolerable. If a clinic dose is delayed, ask whether your tablets and supportive medicines should continue; do not assume all components stop together.

Missed or vomited doses

If you remember a missed dose within 12 hours of its usual time, take it. If more than 12 hours have passed, skip it and take the next dose at its scheduled time. Do not take an extra dose to catch up. Ask the pharmacist if you are unsure about the timing.

If you vomit at any time after swallowing lazertinib, do not take replacement tablets. Take the next dose at the usual scheduled time. Contact the team if vomiting persists or you cannot keep fluids down, because dehydration may require treatment. Seek urgent advice if you accidentally take more than prescribed.

Swallowing, storage and disposal

There is no commercially supplied Lazcluze liquid. Administration instructions differ by region: US information says to swallow tablets whole, while current European information includes a specified water-dispersion method and nasogastric-tube administration. Tell the specialist pharmacist if swallowing is difficult or you use a tube so they can check your exact product and give the applicable instructions. Do not crush, split or chew tablets or improvise a preparation method.

Keep tablets secure and out of children's reach. US instructions specify 20–25°C (68–77°F), allowing brief excursions to 15–30°C (59–86°F); European information requires no special storage conditions. Follow your supplied pack, and ask about protection during hot-weather travel. Return unwanted medicine to the pharmacy.

Understanding the amivantamab appointment

Amivantamab may be given into a vein or through a separate formulation under the skin. The subcutaneous product contains hyaluronidase to help delivery into the tissue; its US brand is Rybrevant Faspro. The products have different doses and preparation instructions and are not interchangeable milligram for milligram. Tell the team about any hyaluronidase allergy before subcutaneous treatment.

With intravenous treatment, the first dose is split across two consecutive days and the initial visits can take several hours. The initial weekly phase is followed by less frequent visits. Subcutaneous treatment starts with weekly doses for four weeks; current US information includes every-two-week or every-four-week schedules from week five, using different doses. Each injection takes approximately five minutes, but the whole appointment takes longer.

Premedication and observation depend on the exact formulation. The current US intravenous plan includes steroid tablets before the first treatment day as well as medicines at the clinic. Subcutaneous premedication has its own schedule. Make sure you have the instructions in advance; a shorter injection does not remove the possibility of an allergic or administration reaction.

Monitoring and checking whether treatment is working

Blood tests assess blood counts, liver and kidney function, albumin and electrolytes. Liver abnormalities may appear before symptoms. The team chooses the frequency according to results, symptoms and the complete regimen; there is no single weekly testing rule suitable for every patient.

At visits, report changes in breathing, swelling, skin, nails, eyes, sensation, appetite or bowel habit. The team also checks adherence and whether the preventive anticoagulant and skin treatments are practical and tolerable.

Scans and clinical assessments show whether the cancer is responding or remaining controlled. The schedule depends on your situation. A rash is not proof that treatment is working, and having little rash does not mean it is failing. Do not use side effects as a substitute for the planned assessment.

Different adverse effects may require holding or reducing one medicine before the other. Sometimes amivantamab is stopped while lazertinib continues, under specialist supervision. Suspected lung inflammation is different: both medicines should be withheld during investigation and permanently stopped if interstitial lung disease or pneumonitis is confirmed.

Common side effects and practical management

Rash and dry or itchy skin

An acne-like rash often affects the face, scalp or upper body, but it is not ordinary teenage acne. Harsh acne treatments and drying products may worsen irritation. Use the prescribed prevention plan, gentle cleansing and a moisturiser that does not clog pores. Tell the team early if the rash becomes painful, spreads or disrupts sleep.

Current prevention guidance includes a prescribed oral antibiotic, such as doxycycline or minocycline, for the first 12 weeks, followed by an antibiotic scalp lotion for the next nine months. Moisturiser is used on the face and body, excluding the scalp. A daily hand-and-foot wash is also recommended; the US label specifies 4% chlorhexidine. These are clinician-directed treatments, not a reason to buy and start antibiotics independently.

The team should explain each product's use and alternatives for allergy or intolerance. Keep antiseptic out of the eyes and use it only on the instructed areas. Limit sun exposure, wear protective clothing and use broad-spectrum UVA/UVB sunscreen during treatment and for two months afterwards.

Nail-fold inflammation

Skin around fingernails or toenails can become red, tender, swollen or infected. Keep nails tidy, avoid cutting cuticles or picking the surrounding skin, and protect hands during wet work. Report pain, discharge or difficulty using fingers or walking. Early treatment can prevent a small sore area becoming a persistent problem.

Mouth soreness and digestive effects

Use a soft toothbrush and gentle mouth care. Avoid foods that sting if your mouth is sore, and contact the team if ulcers interfere with eating or drinking. Prescribed mouth treatments may help. Nausea and reduced appetite can be managed with small meals, regular sips and the recommended anti-sickness medicine.

Diarrhoea needs early attention. Follow the supplied anti-diarrhoea plan and replace fluids within any heart or kidney restriction. Persistent loose stools, dizziness, very little urine, fever, blood in the stool or inability to drink needs urgent advice. Constipation can also occur; ask for a suitable bowel plan rather than alternating unapproved laxatives and anti-diarrhoea medicines.

Swelling, tiredness, aches and altered sensation

Swollen ankles or hands may relate to treatment or low albumin. Report new or worsening swelling, especially if only one limb is affected. Do not assume a painful swollen leg is routine fluid retention. A blood clot must be excluded promptly.

Balance rest with gentle activity when safe. Tell the team about pain that limits daily life, persistent tingling or numbness, or unusual weakness. It may be possible to improve symptoms with supportive treatment or a dose adjustment. Before using painkillers, check whether your anticoagulant or other medicines make bleeding more likely.

Important risks and serious side effects

Blood clots and their prevention

The lazertinib–amivantamab combination can cause serious or fatal clots in veins, including a clot travelling to the lungs. This is called venous thromboembolism, or VTE. Risk is particularly important early in treatment, but it does not disappear after the first few months.

US instructions require preventive anticoagulation for the first four months. European Lazcluze information recommends preventive anticoagulation when treatment starts, with a suitable direct-acting oral anticoagulant or low-molecular-weight heparin. Vitamin K antagonists such as warfarin are not recommended for this prevention approach. The team must select a medicine that fits your bleeding risk, kidney function and other prescriptions.

Do not stop prevention automatically at four months. The clinician reassesses whether to continue it. Report one-sided leg or arm swelling, pain or tenderness immediately. Sudden breathlessness, chest pain, coughing blood or collapse needs emergency assessment even if you are taking the preventive medicine.

If a clot occurs, anticoagulant treatment and cancer-drug changes depend on severity. Recurrent clots despite therapeutic anticoagulation can require permanent stopping of amivantamab while lazertinib may continue at the clinician's discretion. Do not make that decision yourself.

Bleeding while taking an anticoagulant

A preventive blood thinner reduces clot risk but can increase bleeding. Tell the team about unusual bruising, persistent nosebleeds, red urine, black stools or bleeding gums. Uncontrolled bleeding, vomiting blood, collapse or a severe new headache after a fall requires urgent emergency assessment. Do not add aspirin or anti-inflammatory painkillers without checking.

Lung inflammation

Interstitial lung disease, also called pneumonitis in this context, is inflammation that can interfere with oxygen transfer. New or worsening cough, breathlessness or fever needs immediate assessment. Infection, a clot and cancer-related changes can cause similar symptoms, so do not try to distinguish them at home.

The team should withhold lazertinib and amivantamab while suspected lung inflammation is investigated. Confirmed ILD or pneumonitis requires permanent discontinuation of both under the reviewed labels. Severe breathing difficulty is an emergency; do not wait for the next appointment.

Liver injury

The combination can cause significant liver injury. Blood tests check enzymes called ALT and AST and bilirubin before and during treatment. Report yellow skin or eyes, dark urine, pain in the upper right abdomen, unusual loss of appetite or marked tiredness. These symptoms need assessment rather than assuming they are ordinary treatment fatigue.

Severe abnormalities may require withholding both medicines, followed by a lower dose, continuation of lazertinib alone or permanent stopping, depending on recovery. Avoid starting herbal “liver support” remedies; they may introduce further interactions or liver injury.

Eye problems and severe skin reactions

Red or painful eyes, light sensitivity, blurred vision or a change in sight needs prompt assessment by an eye specialist. Keratitis means inflammation of the cornea, the clear front of the eye. Stop wearing contact lenses until symptoms have been assessed, and do not use leftover steroid eye drops. Sudden loss of vision requires urgent emergency assessment.

A painful, widespread rash with blisters, peeling or sores needs immediate help. Severe skin reactions can require stopping amivantamab and withholding or reducing lazertinib; the exact action is specialist-led and differs from management of a mild rash. Fever or signs of infection in damaged skin also need prompt treatment.

Other medicines, supplements and vaccinations

Inducers of the CYP3A4 enzyme can lower lazertinib exposure. US guidance avoids both strong and moderate inducers; European information avoids strong inducers and advises caution with moderate ones. Examples include carbamazepine, phenytoin, rifampicin, St John's wort and certain other medicines. Have alternatives arranged by the prescriber; never abruptly stop an epilepsy medicine yourself.

Lazertinib can increase exposure to medicines processed by CYP3A4 or transported by BCRP. Medicines with a narrow safety margin, and some cholesterol-lowering medicines such as rosuvastatin, need individual checking. Tell every prescriber about lazertinib, amivantamab, the anticoagulant and the skin-prevention antibiotics.

Do not copy interaction restrictions from another EGFR tablet. European Lazcluze information does not require a dose adjustment solely because of a CYP3A4 inhibitor, although the full combination of medicines still needs review. Spacing tablets by a few hours does not reliably solve enzyme interactions. Ask before using supplements, concentrated herbal products or non-prescription treatments.

Discuss vaccination timing with your team. Live vaccines may be unsuitable when immunity is weakened; non-live vaccines may be offered but can be less effective. The full treatment and immune recovery determine advice, not a fixed class-wide waiting period after lazertinib.

Everyday life during treatment

A written daily plan can help separate the cancer tablet, anticoagulant, skin antibiotic and clinic premedication. Mark any missed doses and bring the record to appointments.

Gentle regular movement is helpful when you feel able, but does not replace anticoagulation. Plan travel with the team, especially long journeys or trips far from medical care. Keep monitoring appointments, carry medicines in labelled packaging and have a plan for access to urgent treatment.

Do not drive or use machinery if fatigue, dizziness, visual symptoms or numbness affects concentration or safe control. Sedating amivantamab premedication can also affect the journey home. Discuss flexible work and help with daily tasks during the initial treatment period.

Tell dentists and surgeons about both cancer medicines and your blood thinner before procedures. Changes to anticoagulation or treatment must be coordinated. Use hand hygiene, safe food handling and sensible infection precautions, and ask for support with anxiety, sleep or changes in appearance.

Fertility, contraception, pregnancy and breastfeeding

Lazertinib can harm a developing baby. A pregnancy test is needed before treatment for patients who could become pregnant. Use effective contraception during lazertinib and for three weeks after the final dose; this also applies to male patients with partners who could become pregnant. European information additionally advises men not to donate or store semen during treatment and for three weeks afterwards.

The amivantamab component requires a longer precaution for patients who could become pregnant: contraception during treatment and for three months after its last dose. Therefore the three-week lazertinib interval must not shorten the full-regimen plan. Contact the team immediately about a suspected pregnancy in you or your partner.

Do not breastfeed during treatment. Lazertinib alone requires a three-week interval afterwards, but the reviewed US amivantamab products require three months after their last dose. Confirm the safe date using both medicines. Animal findings suggest lazertinib may affect male and female fertility; discuss preservation before starting because the effect in humans is uncertain.

After treatment finishes

Continue follow-up for the cancer and any treatment-related problems. Ask when blood tests should be repeated and which skin treatments or anticoagulants should continue. There is no automatic stop date for these medicines based only on the last tablet.

Continue sun protection for two months after treatment and reproductive precautions for the agreed longer interval. Report new breathing symptoms, clot symptoms, bleeding or eye problems even after treatment has stopped. Return unused tablets and restart only with an explicit specialist instruction.

Frequently asked questions