Sotorasib (Lumakras®)

Author: Christina Bach, MBE, LCSW, OSW-C
Content Contributor: Marisa Healy, BSN, RN and Deidre Yarosh, PharmD, MA, BCOP
Last Reviewed: July 12, 2023

Pronounce: SOE-toe-RAS-ib

Classification: KRAS Inhibitor

About: Sotorasib (Lumakras®)

Sotorasib works by targeting and blocking KRAS-G12C, a mutation found in some types of cancer. In some cancers, a mutation causes this protein to be overactive, causing cells to grow and divide too fast. By inhibiting KRAS-G12C, sotorasib prevents the uncontrolled growth of cells that contribute to tumor growth. Your oncology team will test your tumor for this mutation, which must be present in order to receive the medication.

How to Take Sotorasib

Sotorasib comes as a tablet that is taken by mouth once daily with or without food. If you miss a dose, take it as soon as you remember. However, if it is more than 6 hours since you were supposed to take the dose, skip the dose and restart the next day. If you vomit after taking a dose, do not take an extra dose. Take your next dose at your regularly scheduled time the next day. Do not take 2 doses at once to make up for a missed dose.

Try to take sotorasib at around the same time every day. Take the tablet whole, do not break, crush or chew. If you cannot swallow sotorasib tablets whole, you can place them in 4 ounces (120 mL) of non-carbonated, room-temperature water without crushing the tablets and stir until the tablets are in small pieces (they will not dissolve completely). Do not chew pieces of the tablet. You should drink the mixture right away or within 2 hours of mixing it, and add another 4 ounces of water to the glass and drink it to be sure you’ve gotten all the medication.

It is important to make sure you are taking the correct amount of medication every time. Before every dose, check that what you are taking matches what you have been prescribed.

The blood levels of this medication can be affected by certain foods and medications, so they should be avoided. These include grapefruit, grapefruit juice, ketoconazole, rifampin, phenytoin, St. John’s wort, and carbamazepine. Be sure to tell your healthcare provider about all medications and supplements you take. If you take warfarin (Coumadin), you should monitor your INR closely, as this medication can cause an increase in bleeding time. Let your provider know if you take digoxin.

The levels of this medication can also be affected by medications used to treat heartburn. Do not take proton pump inhibitors (for example, omeprazole (Prilosec®), esomeprazole (Nexium®), pantoprazole (Protonix®), lansoprazole (Prevacid®) or H2 receptor antagonists (for example, famotidine (Pepcid®) while on sotorasib. If taken with a locally acting antacid (for example, calcium carbonate (TUMS®), take sotorasib 4 hours before or 10 hours after a local antacid.

Storage and Handling

Store your medication in the original, labeled container at room temperature and in a dry location (unless otherwise directed by your healthcare provider or Pharmacist). This medication should not be stored in a pillbox. Keep containers out of reach of children and pets.

If a caregiver prepares your dose for you, they should consider wearing gloves or pour the pills directly from their container into the cap, a small cup, or directly into your hand. They should avoid touching the pills. They should always wash their hands before and after giving you the medication. Pregnant or nursing women should not prepare the dose for you. Ask your oncology team where to return any unused medication for disposal. Do not flush down the toilet or throw in the trash.

Where do I get this medication?

Certain cancer medications, including sotorasib, are only available through specialty pharmacies. If you need to get this medication through a specialty pharmacy, your provider will help you start this process. Where you can fill your prescriptions may also be influenced by your pharmaceutical insurance coverage. Ask your healthcare provider or pharmacist for assistance in identifying where you can get this medication.

Insurance Information

This medication may be covered under your prescription drug plan. Depending on your diagnosis and fund availability, co-pay assistance from private foundations may be available. Patient assistance may be available to qualifying individuals, depending on your prescription drug coverage. Co-pay cards, which reduce the patent co-pay responsibility for eligible commercially (non-government sponsored) insured patients may also be available. Your care team can help you find these resources if they are available.

Possible Side Effects of Sotorasib

There are a number of things you can do to manage the side effects of sotorasib. Talk to your care team about these recommendations. They can help you decide what will work best for you. These are some of the most common or important side effects:


Your oncology care team can recommend medications to relieve diarrhea. Also, try eating low-fiber, bland foods, such as white rice and boiled or baked chicken. Avoid raw fruits, vegetables, whole grain breads, cereals, and seeds. Soluble fiber is found in some foods and absorbs fluid, which can help relieve diarrhea. Foods high in soluble fiber include applesauce, bananas (ripe), canned fruit, orange sections, boiled potatoes, white rice, products made with white flour, oatmeal, cream of rice, cream of wheat, and farina. Drink 8-10 glasses of non-alcoholic, un-caffeinated fluid a day to prevent dehydration.

Electrolyte Abnormalities

This medication can affect the normal levels of electrolytes (sodium, calcium, etc.) in your body. Your levels will be monitored using blood tests. If your levels become too low, your care team may prescribe specific electrolytes to be given by IV or taken by mouth. Do not take any supplements without first consulting with your care team.

Muscle or Joint Pain/Aches

Your healthcare provider can recommend medications and other strategies to help relieve pain.


Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.

Nausea and/or Vomiting

Talk to your oncology care team so they can prescribe medications to help you manage nausea and vomiting. In addition, dietary changes may help. Avoid things that may worsen the symptoms, such as heavy or greasy/fatty, spicy or acidic foods (lemons, tomatoes, oranges). Try saltines, or ginger ale to lessen symptoms.

Call your oncology care team if you are unable to keep fluids down for more than 12 hours or if you feel lightheaded or dizzy at any time.

Liver Toxicity

This medication can cause liver toxicity, which your oncology care team may monitor for using blood tests called liver function tests. Notify your healthcare provider if you notice yellowing of the skin or eyes, your urine appears dark or brown, or you have pain in your abdomen, as these can be signs of liver toxicity.

Infection and Low White Blood Cell Count (Leukopenia or Neutropenia)

White blood cells (WBC) are important for fighting infection. While receiving treatment, your WBC count can drop, particularly your lymphocytes, putting you at a higher risk of getting an infection. You should let your doctor or nurse know right away if you have a fever (temperature greater than 100.4°F or 38°C), sore throat or cold, shortness of breath, cough, burning with urination, or a sore that doesn't heal.

Tips to preventing infection:

  • Washing hands, both yours and your visitors, is the best way to prevent the spread of infection.
  • Avoid large crowds and people who are sick (i.e.: those who have a cold, fever, or cough or live with someone with these symptoms).
  • When working in your yard, wear protective clothing including long pants and gloves.
  • Do not handle pet waste.
  • Keep all cuts or scratches clean.
  • Shower or bathe daily and perform frequent mouth care.
  • Do not cut cuticles or ingrown nails. You may wear nail polish, but not fake nails.
  • Ask your oncology care team before scheduling dental appointments or procedures.
  • Ask your oncology care team before you, or someone you live with has any vaccinations.

Low Red Blood Cell Count (Anemia)

Your red blood cells are responsible for carrying oxygen to the tissues in your body. When the red cell count is low, you may feel tired or weak. You should let your oncology care team know if you experience any shortness of breath, difficulty breathing, or pain in your chest. If the count gets too low, you may receive a blood transfusion.

Less common, but important side effects can include:

  • Pneumonitis/ Interstitial Lung Disease:Patients can develop an inflammation of the lungs (called pneumonitis) while taking this medication. Notify your oncology care team right away if you develop any new or worsening symptoms, including shortness of breath, trouble breathing, cough, or fever.

Reproductive Concerns

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive. You should not breastfeed while taking this medication and for 1 week after the final dose.