Avutometinib and Defactinib: Uses, Side Effects, and Precautions

What Are Avutometinib and Defactinib?

Avutometinib and Defactinib are cancer medicines (called antineoplastics). They help stop cancer from growing.

Avutometinib:

• Avutometinib is a special medicine that works in a new and different way (a first-in-class approach).

• It is an oral RAF/MEK (rapidly accelerated fibrosarcoma and mitogen-activated protein kinase kinase) inhibitor.

• These RAF and MEK are the enzymes in the MAPK (mitogen-activated protein kinase) pathway.

• This MAPK pathway relays signals from outside the cell to the cancer cell’s control center, keeping it growing.

Defactinib:

• Defactinib works by slowing down two helpers (enzymes) in cancer cells called FAK (focal adhesion kinase) and Pyk2 (proline-rich tyrosine kinase 2).

• These enzymes tell cancer cells how to survive, form new blood vessels, and spread to other parts of the body (metastasize).

• Defactinib helps stop those messages, making it harder for cancer cells to grow and spread.

Avutometinib and Defactinib, when combined, are effective in treating a rare type of ovarian cancer called KRAS (Kirsten rat sarcoma viral oncogene homologue) - mutated low-grade serous ovarian cancer (LGSOC). This cancer can come back, does not always respond to regular treatments, and is often found in younger people. These medicines work by blocking key signaling pathways in cancer cells that tell them to grow and make more copies of themselves.

Are Avutometinib and Defactinib Approved by the FDA?

Yes! Avutometinib and Defactinib were approved by the FDA (Food and Drug Administration) on May 8, 2025.

How Does the Combination Work?

These two medicines work together by targeting two different pathways in cancer cells. Let’s learn how they do this, step by step!

Avutometinib:

• Avutometinib inhibits RAF/MEK enzymes. These helpers are part of the MAPK pathway that keeps telling cancer cells to grow. This medicine doesn’t just turn off MEK; it also prevents RAF from turning MEK back on.

• This medicine also stops the cancer cells from turning the RAF-MEK-ERK pathway back on after it has been turned off. That way, the cells can’t “bounce back” and start growing again.

Defactinib:

• Defactinib is a medicine that blocks a helper called FAK. This helper is present in abundance in many cancer cells and helps link the extracellular matrix to the intracellular environment.

• When Defactinib blocks FAK, it also quiets other growth pathways, such as the RAS-MEK-ERK (MAPK) and PI3K-Akt pathways.

• This makes it harder for cancer cells to survive, move, and spread to new places.

• Defactinib also helps clean up the area around the tumor by reducing stiff tissue and improving the body’s immune system's ability to fight the cancer.

Most of the time, cancer cells find sneaky ways to keep growing, even when you give them just one medicine. They switch to different pathways to stay alive. When Avutometinib (which blocks MEK) and Defactinib (which blocks FAK) are used together, they stop both the main growth messages and the sneaky backup pathways. This makes it much stronger at fighting cancer that comes back, like LGSOC.

What Are Avutometinib and Defactinib Used For?

This medicine team is used to treat adults with a type of ovarian cancer called KRAS-mutated low-grade serous ovarian cancer (LGSOC) that has come back after other treatments.

Scientists are also studying this medicine team to see if it can help with other cancers that use the same growth pathways, like

• Colon cancer.

• Pancreatic cancer.

• Lung cancer.

• Endometrial cancer.

What Is the Dosage of Avutometinib and Defactinib?

These medicines come as tablets and capsules that you take by mouth. The dosage for adults with ovarian cancer is:

• Avutometinib: It is given as 3.2 mg (four 0.8 mg capsules) by mouth two times a week, on day 1 and day 4, for 3 weeks. Then take 1 week off before starting again.

• Defactinib: It is given as 200 mg two times a day for 3 weeks, then take 1 week off.

If you miss a dose:

• Take it as soon as you remember.

• If it’s almost time for your next dose, skip the missed dose and resume your regular schedule.

Precautions:

• Don’t crush, chew, or split the pills.

• Don’t take medicine for your stomach acid at the same time as Defactinib.

• If you throw up after taking a pill, don’t take another one. Wait for your next dose.

What Are the Side Effects of Avutometinib and Defactinib?

Here are some side effects that might happen:

• Feeling sick to your tummy (nausea).

• Throwing up.

• Pooping too much (diarrhea) or not enough (constipation).

• Heartburn or tummy aches.

• Rashes or red spots on your skin.

• Dry skin.

• Hair might fall out a little.

• Itchy skin.

• Feeling very tired or weak.

• Swelling in your hands or feet.

• Achy joints or muscles.

• Not feeling hungry.

• Food might taste funny.

• Sores in your mouth.

• Feeling dizzy or getting headaches.

• Pain when peeing.

• Bleeding gums.

• Pee that is cloudy or has blood.

Serious things that can happen:

• Eyes: Blurry vision, seeing halos around lights, or problems with the retina.

• Liver: Pain on the right side of your belly, yellow skin or eyes (jaundice), or lab tests showing liver problems.

• Muscles: Very bad pain or weakness.

• Blood Problems: Your body might make fewer blood cells, which can cause easy bruising, bleeding, or infections.

• Blood Clots: These include deep vein thrombosis or pulmonary embolism.

What Precautions Should Be Taken While Taking Avutometinib and Defactinib?

• These medicines can cause birth defects, so pregnant women should not take them.

• Both men and women need to use birth control:

  • Women: During treatment and for 1 month after.

  • Men: During treatment and for 4 months after.

• These medicines might make it harder to have babies (infertility), so doctors will talk with you about it.

• Do not breastfeed for at least 2 weeks after your last dose, because the medicine can go into breast milk.

• These medicines can make your skin burn faster in the sun. Protect yourself by wearing sunscreen (SPF), hats, or protective clothing and avoiding too much sun.

• You will need regular check-ups, such as eye and skin exams and blood tests.

• Avoid grapefruit or grapefruit juice, and also alcohol unless your doctor says it’s okay, because it can change how the medicine works.

Conclusion:

Avutometinib and Defactinib are cancer medicines that are taken orally. They help treat a rare and tricky cancer called KRAS-mutated LGSOC, especially in people who have tried other treatments before. Avutometinib and Defactinib inhibit enzymes that slow or stop cancer cell growth.

Like all medicines, they can cause side effects; some are common, and some are serious. However, there is nothing to worry about. If you are taking these medicines and have side effects or need help, contact a cancer specialist.

Key Takeaways:

• Avutometinib and Defactinib are a team of medicines that work effectively in treating a rare cancer in adults called KRAS-mutated low-grade serous ovarian cancer.

• These medicines work by stopping the pathways that tell cancer cells to grow. They block the main path the cancer uses and other backup paths it tries to use. Because of this, the medicines work better.

• Avutometinib and Defactinib have helped about 44 out of 100 people get better and have shrunk tumors by blocking the KRAS-MAPK pathway that drives cancer cell growth.

• If you have very severe side effects, such as blurred vision, tummy pain, severe muscle pain, or bleeding, you should see the doctor right away.