Mekinist (trametinib)

Reviewed by: HU Medical Review Board | Last reviewed: July 2022 | Last updated: June 2023

Mekinist® is a treatment used in combination with Tafinlar® (dabrafenib) for metastatic (has spread to other parts of the body) non-small cell lung cancer (NSCLC) with the BRAF V600E mutation. Trametinib is a kinase inhibitor and is also used in the treatment of certain melanomas with BRAF V600E or V600K mutation, and locally advanced or metastatic anaplastic thyroid cancer with BRAF V600E mutation with no locoregional treatment options.1

How does Mekinist work?

The BRAF V600E mutation is a specific change in the BRAF gene that has been found in some types of cancer, including NSCLC, melanoma, and colorectal cancer. The BRAF gene normally makes a protein that is involved in cell growth, and the mutation may increase the growth and spread of cancer cells.2

Mekinist is an inhibitor of a protein that contributes to cancer growth along the same pathway as the BRAF V600E mutation. When used in combination with dabrafenib, the two medications block different proteins along the same pathway that leads to the growth of cancer cells. By blocking these proteins, the combination of Tafinlar and trametinib inhibit the growth of the cancer.1,3

What are the possible side effects of trametinib?

When used with dabrafenib, trametinib may cause skin cancers such as cutaneous squamous cell carcinoma, melanoma, keratoacanthoma or basal cell carcinoma.

Trametinib may cause serious bleeding issues, including brain or stomach bleeds, and this can lead to death. Seek immediate medical attention if you have any signs of bleeding, including:

  • Headaches
  • Dizziness
  • Feeling weak
  • Coughing up blood or blood clots
  • Vomiting blood (may look like coffee grinds)
  • Red or black stools (may look like tar)3

Trametinib may cause inflammation of the intestines, or a perforation (tear) in the stomach or intestines. This is serious and can lead to death. Seek immediate medical attention if you have any of the following symptoms:

  • Bleeding
  • Diarrhea or more frequent bowel movements than usual
  • Abdominal pain or tenderness
  • Fever
  • Nausea3

Trametinib can cause blood clots in the arms or legs. If blood clots travel to your lungs, they can lead to death. Seek immediate medical attention if you have any signs of blood clots, including:

  • Chest pain
  • Sudden shortness of breath or difficulty breathing
  • Swelling in the arms or legs
  • A cool, pale arm or leg3

Trametinib can cause heart problems, including heart failure. Your doctor should check your heart function before and during treatment with trametinib. Call your doctor if you have any signs of a heart problem, including:

  • Racing heartbeat
  • Shortness of breath
  • Swelling in the feet or ankles
  • Lightheadedness3

Trametinib can cause serious eye problems, and some can lead to blindness. Call your doctor if you have any signs of eye problems, including:

  • Blurry vision, loss of vision, or other changes
  • Seeing colored dots
  • Seeing a halo around objects
  • Eye pain, swelling, or redness3

Trametinib can cause problems with the lungs or breathing. Call your doctor if you have any signs of lung problems, including:

  • Shortness of breath
  • Cough3

Trametinib frequently causes a fever. Occasionally, a fever can be serious, if it causes dehydration, low blood pressure, dizziness, or kidney problems. Tell your doctor right away if you experience a fever with trametinib.3

Trametinib can cause serious skin reactions, like a rash. Call your doctor if you have any signs of skin reactions, including:

  • A rash or redness that bothers you or doesn’t go away
  • Acne
  • Redness, blistering or peeling of the skin3

Trametinib can cause increased blood sugar (hyperglycemia). If you have diabetes, you will need to check your blood sugar levels closely, as trametinib may worsen your diabetes. Call your doctor if you have any signs of severe high blood sugar, including:

  • Increased thirst
  • Urinating more frequently or urinating an increased amount of urine3

The most common side effects experienced by NSCLC patients in clinical trials taking trametinib in combination with dabrafenib include:

  • Fever
  • Fatigue
  • Nausea
  • Vomiting
  • Diarrhea
  • Dry skin
  • Decreased appetite
  • Rash
  • Swelling of face, arms, and legs
  • Chills
  • Bleeding
  • Cough
  • Shortness of breath3

Trametinib can cause or worsen high blood pressure (hypertension). People taking trametinib should have their blood pressure checked frequently during treatment. Call your doctor if you develop high blood pressure, if your blood pressure worsens, or if you have severe headache, lightheadedness, or feel dizzy.3

Trametinib can cause fertility problems in women, which may affect your ability to become pregnant.3

This is not an exhaustive list of all potential side effects of trametinib. Talk to your healthcare provider or pharmacist for further information.

Things to know about trametinib

Trametinib should only be used in NSCLC patients who have the BRAF V600E mutation. Your doctor will perform a test to see if your NSCLC has this mutation.3

Because of the increased risk of developing some kinds of skin cancer, you should have your skin checked by a doctor before starting treatment with trametinib, every two months during treatment, and for up to six months after you stop taking trametinib for any new skin cancers. In addition, you should check your skin regularly and contact your doctor if you see any skin changes, such as a new wart, a sore or reddish bump that bleeds or doesn’t heal, or a change in the size or color of a mole.1,3

Before starting treatment with trametinib, talk to your doctor about all your health conditions, including:

  • Bleeding problems
  • Heart (cardiovascular) problems
  • Stomach problems
  • Inflammation of the colon
  • Eye problems
  • Lung or breathing problems
  • High blood pressure (hypertension)
  • Liver or kidney problems
  • Pregnancy or planning to become pregnant
  • Breastfeeding or planning to breastfeed1,3

Talk to your doctor about all medications you are taking, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Trametinib may change how other medicines work, and certain combinations of medicine can cause side effects.3

If you are pregnant, plan to become pregnant, or are breastfeeding or plan to breastfeed, talk with your doctor. Trametinib can cause harm to a developing fetus and should not be taken by women who are pregnant. While taking trametinib, males with female partners who can become pregnant, and females who can become pregnant, should both use contraceptives during treatment and for a period of time after completing treatment (patients should discuss appropriate birth control methods, and how long they need to use them, with their doctor). Females should not breastfeed during trametinib treatment and for a period of time following the final dose (patients should discuss breastfeeding considerations with their doctor).1,3

Receiving trametinib

Trametinib comes in a tablet that is taken by mouth (in combination with dabrafenib for NSCLC). Patients should take their medication as prescribed by their doctor. Patients should talk to their doctor if they have any questions, or if they have questions regarding their trametinib (or dabrafenib) regimen.1

For more information, read the full prescribing information for trametinib.

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