Sotorasib (Lumakras and Lumykras)

Medicine at a glance

Sotorasib is a targeted cancer treatment taken by mouth once a day. Verified brands include Lumakras and Lumykras. It blocks a particular changed protein called KRAS G12C. A test must show that this specific change is present before the team considers treatment; the words “KRAS mutation” alone are not enough.

You may receive sotorasib by itself or, in a particular treatment plan, with the antibody medicine panitumumab. Food is optional, but the prescribed dose and medicine-interaction instructions matter. The principal serious concerns are liver injury and lung inflammation. Diarrhoea, nausea, fatigue and muscle or joint discomfort also deserve early attention.

This guide concerns adult treatment; safety and effectiveness in children have not been established.

This guide supports discussions with your treating team. Your prescription, product leaflet and individual care plan determine exactly how you take treatment.

What sotorasib is and how it works

KRAS is part of a signalling system inside cells. The G12C change can keep growth signals active when they should be switched off. Sotorasib binds to this altered protein and holds it in an inactive state, helping interrupt signals that support cancer growth. It does not target every possible KRAS change.

Sotorasib is a small-molecule targeted medicine, rather than conventional chemotherapy or an immune-checkpoint treatment. “Targeted” does not mean that it affects only cancer cells or cannot cause serious side effects. Response varies, and a cancer can become resistant over time. Scans and clinical assessment are needed to understand whether it is helping you.

Panitumumab, when prescribed alongside it, blocks another growth-signal protein called EGFR. This is a specifically selected combination. Do not add, omit or substitute an accompanying cancer medicine yourself. Its skin, eye, electrolyte and infusion precautions are additional to sotorasib's precautions.

How the team decides whether it is suitable

The oncologist considers your diagnosis, KRAS G12C result, previous medicines, general health and current prescribing guidance. Depending on the clinical setting, testing may use tumour tissue or blood containing DNA released by the cancer. A negative blood test does not always exclude the mutation: the US label requires tumour testing after a negative plasma result in the setting where plasma testing is used.

The team also weighs liver disease, previous lung inflammation, kidney function and medicines you already need. Give the dates of your last immunotherapy treatment and any earlier immune-related liver or lung problem. Recent immunotherapy can materially affect safety planning.

Regional liver guidance differs. The US label does not require an initial dose change for mild or moderate liver impairment, but advises closer monitoring. European guidance does not recommend treatment in moderate or severe liver impairment. Severe kidney impairment also has limited evidence. These decisions belong to your oncologist; an internet dosing example cannot resolve them.

Before treatment starts

Bring a complete list of prescriptions, over-the-counter medicines, supplements and herbal products. Include acid-reflux remedies even if you take them only occasionally. Tell the team about allergies, liver or kidney disease, breathing problems, previous radiotherapy, pregnancy possibility and breastfeeding. The tablets contain lactose; tell the team about a diagnosed inherited sugar-absorption disorder. European guidance says people with rare hereditary galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take this product. These are distinct from ordinary dietary lactose intolerance.

Baseline blood tests check liver enzymes and bilirubin, kidney function, blood counts and relevant salts. The team records your usual bowel pattern, appetite, weight and breathing symptoms so changes are easier to recognise. If panitumumab accompanies treatment, magnesium, calcium and potassium monitoring and a preventive skin-care plan are particularly important.

Before leaving, understand your daily dose, tablet strength, missed-dose rule and which symptoms need an urgent call. Obtain your hospital's own urgent contact arrangements. Check how to get repeat prescriptions and blood tests before your supply runs out.

How to take sotorasib

Dose, food and tablet strengths

A usual adult starting dose is 960 mg once daily, at approximately the same time each day, with or without food. This is an example, not an instruction to change your prescription. Side effects may require a pause or reduction to 480 mg and then 240 mg daily. Do not break tablets to invent a reduced dose.

US Lumakras tablets come in 120 mg, 240 mg and 320 mg strengths. The current European Lumykras information lists 120 mg and 240 mg tablets. Thus, 960 mg can mean eight 120 mg tablets, four 240 mg tablets or, for the US product, three 320 mg tablets. Check the strength and written number after every refill. Swallow tablets whole; do not chew, crush or split them.

If swallowing is difficult

There is a verified water-dispersion method. Ask the pharmacist to demonstrate it using your prescribed product. Put the whole prescribed tablets in 120 mL of still, room-temperature water without crushing. Use no other liquid. Stir until small pieces form; the tablets do not completely dissolve. The US instructions specify stirring or swirling for about three minutes. Drink the mixture without chewing the pieces, then rinse the container with another 120 mL of water and drink that too.

Prepare it for immediate use. If delayed, stir again and use within two hours; discard a dispersion kept longer. Tell the team if you have a fluid restriction. Do not use cola as the mixing liquid, even if a clinician has separately prescribed an acidic beverage for an interaction plan. European instructions also support the dispersion through a nasogastric or PEG feeding tube with appropriate rinses and flushes. The US label describes oral dispersion but does not give that tube method. Tube administration needs pharmacy-led, product-specific instructions.

Missed doses, vomiting and storage

If you remember less than six hours after the scheduled time, take the missed dose. If more than six hours have passed, skip it and take the next dose at the usual time the next day. Never double up. At the exact six-hour boundary, follow your own leaflet or pharmacist's instruction: US patient wording permits taking it unless more than six hours have passed, while European wording leaves that exact boundary unstated.

If you vomit after taking sotorasib, do not take a replacement dose. Resume at the usual time the next day and report repeated vomiting. For an accidental extra dose, contact the team promptly with the strength, number and time taken.

Keep tablets in their original packaging, away from children and pets, and follow the storage label. US storage is normally 20–25°C (68–77°F), with permitted short excursions to 15–30°C (59–86°F). Avoid a hot car or damp bathroom. Return unused tablets through the pharmacy rather than household waste or drains.

When panitumumab is also prescribed

Panitumumab is given through a vein, usually every two weeks in this combination. The first sotorasib dose is taken before the first panitumumab infusion; follow the treatment unit's instructions. If sotorasib is withheld or stopped, the team also withholds or stops panitumumab under the US combination instructions. The reverse decision can differ: a clinician may continue sotorasib after panitumumab is permanently stopped. Never make that decision yourself.

Monitoring and checking whether treatment is working

Liver blood tests are required before treatment, every three weeks for the first three months, then monthly or as clinically indicated. More frequent testing may be needed for abnormal results, liver disease or recent immunotherapy. Tests can detect injury before you notice symptoms, so feeling well is not a reason to skip them.

Other blood tests follow kidney function, blood counts and salts. With panitumumab, magnesium and calcium are checked before treatment, periodically during it and for up to eight weeks after completion; potassium may also need replacement. Low salts can sometimes cause muscle cramps, weakness, confusion or an abnormal heartbeat.

Scans are planned at intervals suited to your cancer and treatment. The team also considers symptoms, weight, activity and side effects. Keeping a short diary of tablets, bowel changes, breathing and new medicines helps appointments. A dose reduction is a safety decision and does not by itself prove treatment has failed.

Common side effects and practical management

Diarrhoea and dehydration

Record how often you pass loose stools compared with your normal pattern. Tell the team early, particularly if diarrhoea continues, wakes you at night or increases stoma output. Use the anti-diarrhoea plan they provide. Frequent sips and suitable rehydration fluids may help; ask for an individual fluid target if you have heart or kidney disease.

Seek urgent advice for dizziness, little urine, fever, blood in the stool, severe pain or inability to keep fluids down. Severe diarrhoea can lead to dehydration and kidney injury. Do not keep escalating over-the-counter diarrhoea medicine while these warning signs are present.

Nausea, vomiting and appetite

Small, frequent meals and regular sips may be easier than a large meal. Take prescribed anti-sickness medicine as directed. Report repeated vomiting, falling weight or difficulty eating; the team can adjust supportive medicines and involve a dietitian. Remember that vomiting does not justify an extra sotorasib dose.

Tiredness, anaemia and pain

Pace activities and include gentle movement when you can. Low red blood cells, called anaemia, may contribute to fatigue, dizziness or breathlessness. New breathlessness still needs assessment rather than being assumed to be anaemia. Blood tests help separate possible causes.

Muscle, joint or back pain can occur. Ask which pain reliever is suitable before buying one, particularly if you have liver or kidney concerns. Report pain that is new, persistent, severe or limits walking; it may need assessment for causes other than treatment.

Constipation, mouth and skin symptoms

Constipation may improve with gentle activity, appropriate fluids and a recommended laxative. Severe abdominal pain, vomiting, a swollen abdomen or inability to pass stool or wind needs urgent assessment. Do not simply add more fibre when these symptoms suggest a possible blockage.

Skin rash, dryness, sore mouth and nail inflammation are especially relevant with panitumumab. Use gentle skin products and the prescribed prevention plan; avoid picking spots or cutting damaged cuticles. A soft toothbrush and non-irritating mouth care can help. Tell the team if eating is painful or skin becomes hot, swollen, weeping or infected.

Important risks that need medical assessment

Liver injury, including after immunotherapy

Sotorasib can cause drug-induced liver injury or hepatitis, meaning inflammation of the liver. Some changes are detected only on blood tests; others can be severe. Warning signs include yellow eyes or skin, dark urine, pale stools, appetite loss, unusual fatigue, nausea, right-sided upper abdominal pain or unexpected bruising. Contact the team immediately.

Current labels describe more liver toxicity when immunotherapy was given within the previous three months. This is a risk association, not a rule that treatment becomes risk-free after three months or must always wait that long. Give the team exact treatment dates. They may arrange closer tests, withhold sotorasib, reduce it, prescribe corticosteroids or stop it permanently. Do not start leftover steroids yourself.

Lung inflammation

Interstitial lung disease or pneumonitis is inflammation within the lungs and can be life-threatening. New or worsening breathlessness, cough or fever needs immediate assessment. Infection, cancer and inflammation can look similar, so do not try to distinguish them at home. The team withholds sotorasib when this problem is suspected and permanently stops it if treatment-related lung inflammation is confirmed without another cause.

The European information also identifies recent immunotherapy as a possible risk factor for lung inflammation. Tell clinicians about earlier immunotherapy and chest radiotherapy, even when those treatments have finished.

Additional risks with panitumumab

During an infusion, report chills, flushing, tight chest, wheezing, dizziness or swelling immediately. Staff can stop the infusion and treat a reaction. Severe reactions can occur and need emergency care. Panitumumab also adds risks of serious skin infection, blistering skin reactions and eye inflammation. Eye pain, sensitivity to light or a new change in vision requires urgent assessment.

Sun can worsen panitumumab-related skin problems. Use sun protection and limit strong sun during treatment and for two months after its last dose. Dehydration, kidney injury and low magnesium, potassium or calcium need particular attention with the combination. Do not start high-dose mineral supplements without blood-test guidance.

Other medicines, supplements and vaccines

Acid-reducing medicines can lower the amount of sotorasib absorbed. Tell the pharmacist about omeprazole and other proton-pump inhibitors, H2 blockers such as famotidine, and simple antacids. Do not stop a medically necessary stomach medicine without arranging an alternative plan.

The US label advises avoiding proton-pump inhibitors and H2 blockers. If an unavoidable acid remedy is a locally acting antacid, take sotorasib four hours before or ten hours after that antacid. This spacing rule is not a way to make a proton-pump inhibitor safe to combine.

Current European instructions differ: when an acid-reducing medicine such as a proton-pump inhibitor or H2 blocker is required, they describe taking sotorasib with an acidic beverage such as cola. They also note that exposure remains reduced and the clinical importance is unclear, so treatment effectiveness could still be reduced. This needs a deliberate prescribing plan; do not start cola as a home remedy or use it to disperse tablets. European guidance also gives the four-hours-before or ten-hours-after option for a local antacid.

Other interactions involve medicine-processing enzymes and transport proteins. Strong enzyme inducers such as rifampicin, carbamazepine, phenytoin and St John's wort can reduce sotorasib exposure and should be avoided with it. Sotorasib can raise digoxin or rosuvastatin levels, increasing toxicity, while lowering levels of some other medicines, including certain transplant medicines and hormonal contraceptives. Some combinations must be avoided because small changes could cause serious harm. Have every new prescription checked, including antibiotics, pain treatments and supplements. A familiar medicine may now need monitoring or replacement.

Discuss vaccinations with the oncology team. Timing and suitability depend on your overall treatment and immune function, especially if steroids or other cancer medicines are added. Do not assume that all vaccines are prohibited or that a live vaccine is automatically safe.

Everyday life during treatment

Many people continue parts of their normal routine, with adjustments for symptoms and appointments. Choose manageable activity and ask about help with work, travel costs or emotional strain. Persistent worry, low mood or sleep problems deserve support as much as physical symptoms.

Eat what you can tolerate and seek dietary help if weight is falling. Ask about alcohol because liver injury is an important concern. Avoid driving or operating machinery when dizzy, unusually tired, sleepy or visually impaired. Report these symptoms if they persist.

For travel, carry medicine in its labelled packaging with a current prescription and enough supply. Plan blood tests and access to urgent care before departure. Tell your dentist and other clinicians about treatment before procedures; the oncology team should coordinate any interruption. Keep routine hand hygiene and avoid close contact with people who have an active infection.

Pregnancy, contraception, fertility and breastfeeding

Tell the team before treatment if pregnancy is possible or planned, and report a possible pregnancy promptly. Human pregnancy data for sotorasib are limited. Discuss pregnancy testing and a contraception plan before the first dose.

The European label requires highly effective contraception for patients who can become pregnant during treatment and for at least seven days after the last dose. Because sotorasib may make hormonal contraception less effective, add a barrier method if using it. The US sotorasib label does not specify the same standalone contraception interval. Neither label provides a fixed male-partner contraception period; obtain individual advice rather than borrowing an interval from another targeted medicine.

If panitumumab accompanies treatment, its US label requires effective contraception during treatment and for two months after its last dose. The longer applicable partner precaution must be followed. Your team should give a clear final date and suitable methods.

Do not breastfeed during sotorasib. US guidance and the European patient leaflet extend this for one week after the last dose. Panitumumab requires no breastfeeding during treatment and for two months after its last dose. Fertility effects of sotorasib in people remain uncertain. Discuss preservation before treatment if future parenthood matters to you.

After a pause or when treatment finishes

Do not restart leftover tablets after a treatment break until the team confirms the dose and blood results. If you receive panitumumab, confirm both medicines' plans. A lower tablet count may reflect a changed strength, a reduced dose or both.

Continue reporting new breathing symptoms or liver warning signs after treatment ends. Keep arranged blood tests, contraception and breastfeeding precautions. Panitumumab-related electrolyte monitoring may continue for up to eight weeks. Return unwanted medicine safely and clarify the next appointment, scan and supportive-care plan.

Frequently asked questions