Lumakras (Sotorasib): What It Is and What to Expect

KRAS is a switch protein that tells cells to grow. It sits at the top of a chain of signals, and it was considered undruggable for decades because its surface has nowhere obvious for a drug to grip.

One particular fault changes that. In KRAS G12C, a single building block of the protein is swapped for cysteine. Cysteine is chemically reactive, and it gives a drug something to bond to.

Sotorasib grips that cysteine and holds the switch in its off position. It only works on cancers with that exact change. Lumakras is the brand name; sotorasib is the generic name.

A laboratory test on tumor tissue or blood has to find KRAS G12C first. Other KRAS faults, such as G12D or G12V, are not treated by this drug.

If your report says KRAS mutated but does not say which one, ask. The difference decides whether this drug is an option.

Sotorasib has two approved uses.

For non-small cell lung cancer with KRAS G12C that is locally advanced or has spread, it is taken on its own, after at least one earlier treatment.

For metastatic colorectal cancer with KRAS G12C, it is combined with panitumumab, an antibody given by drip, after chemotherapy that included a fluoropyrimidine, oxaliplatin and irinotecan.

The lung cancer use holds an accelerated approval. That is a real FDA approval, granted early on the strength of how many tumors shrank and for how long.

It comes with a condition. The company has to run further trials showing patients actually live longer or better. If those trials do not deliver, the approval can be withdrawn. Some cancer approvals have been.

This is worth knowing because it explains why your team may talk about the evidence as still developing.

The dose is 960 mg once daily, at about the same time each day, with or without food. It is the same total whether you take sotorasib alone for lung cancer or with panitumumab for bowel cancer. That is the label amount. Your own prescription is the one to follow, and your team may lower it if side effects build.

That total can arrive as three 320 mg tablets, four 240 mg tablets, or eight 120 mg tablets. So the number of tablets in your hand depends on the strength dispensed, not on your dose being different.

Go by the label on your own box, not by the figure above. It is the standard starting amount from the manufacturer's label, printed here so the timing and the tablet count make sense to you. Oncology teams often reduce it when side effects appear, and yours may already have.

Swallow them whole. Do not chew, crush or split them. People who cannot swallow tablets can ask about the label's method of dispersing them in plain water. If you miss a dose by more than 6 hours, skip it and take the next one as normal. Never take two at once.

Sotorasib needs stomach acid to dissolve properly. Medicines that reduce acid cut how much drug reaches your blood.

The label says to avoid proton pump inhibitors, such as omeprazole, and H2 blockers, such as famotidine. If an antacid cannot be avoided, sotorasib is taken 4 hours before it or 10 hours after it.

Many people are already on one of these for reflux and never think of it as a real medicine. Say it out loud at your appointment.

Liver trouble is the most common serious effect. In the lung cancer group, 27% of people had it, and 16% had it at a severe grade. It usually appears in the first couple of months.

You will have blood tests before starting and then roughly every few weeks at first. Most people have no symptoms when the numbers move, which is the point of testing.

Call the same day for yellow skin or eyes, dark urine, pain under the right ribs, or unusual tiredness with nausea.

Inflammation of the lung tissue occurred in about 2 in 100 people, and one case was fatal. It came on around two months into treatment on average.

New breathlessness, a new cough, or a fever should be reported at once. Treatment is held while it is checked.

Diarrhea, muscle and joint aches, nausea and tiredness are the everyday effects. They are usually manageable, but tell your team early rather than pushing through.

• Call 911 or go to an emergency department if you are struggling for air while sitting still, or a cough comes with chest tightness and you cannot finish a sentence.
• Call your care team the same day if you notice a new cough, breathing that is worse than it was, or a temperature of 100.4°F (38°C) or higher. The tablet is usually held while your lungs are checked. Ring the same day too for yellow skin or eyes, dark urine, pain under the right ribs, or heavy tiredness with nausea.
• If chemotherapy has been given recently, the fever rule is stricter. CDC treats it as a medical emergency. Call the team the moment you record 100.4°F (38°C), day or night, and go to an emergency department if the call is not picked up.
• Call your care team within a day or two if diarrhea keeps you close to a bathroom, muscle and joint aches stop you moving normally, or you have started an antacid or reflux medicine, which can block how much sotorasib you absorb.

• https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c80a362c-7ac3-4894-a076-0691e68ef8c1
• https://www.cancer.gov/about-cancer/treatment/drugs/sotorasib
• https://www.fda.gov/drugs/resources-information-approved-drugs/withdrawn-cancer-accelerated-approvals