Mekinist (trametinib)

Mekinist® is a treatment used in combination with Tafinlar® (dabrafenib) for metastatic non-small cell lung cancer (NSCLC) with the BRAF V600E mutation. Mekinist is a kinase inhibitor and is also used in the treatment of melanoma with BRAF V600 E or V600K mutations and involvement of lymph nodes, and metastatic anaplastic thyroid cancer with BRAF V600E mutation with no locoregional treatment options.1

What are the ingredients in Mekinist?

The active ingredient in Mekinist is trametinib. Mekinist also contains the inactive ingredients colloidal silicon dioxide, croscarmellose sodium, hypromellose, magnesium stearate (vegetable source), mannitol, microcrystalline cellulose, sodium lauryl sulfate. The coating of the Mekinist tablet also contains hypromellose, iron oxide red (2-mg tablets), iron oxide yellow (0.5-mg tablets), polyethylene glycol, polysorbate 80 (2-mg tablets), titanium dioxide.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 the protein that is created from the BRAF V600E mutation. When used in combination with Tafinlar, 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 Mekinist inhibit the growth of the cancer.1,3

What are the possible side effects of Mekinist?

When used alone or with Tafinlar, Mekinist may cause skin cancers such as cutaneous squamous cell carcinoma or basal cell carcinoma.

Mekinist 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

Mekinist 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

Mekinist 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

Mekinist can cause heart problems, including heart failure. Your doctor should check your heart function before and during treatment with Mekinist. 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

Mekinist 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

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

  • Shortness of breath
  • Cough3

Mekinist 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 Mekinist.3

Mekinist 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, swelling, peeling, or tenderness of the hands or feet3

Mekinist can cause increased blood sugar (hyperglycemia). If you have diabetes, you will need to check your blood sugar levels closely, as Mekinist 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 patients in clinical trials taking Mekinist include:

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

Mekinist can cause or worsen high blood pressure (hypertension). People taking Mekinist 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

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

Things to know about Mekinist

Mekinist should only be used in people 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 Mekinist, every two months during treatment, and for up to six months after you stop taking Mekinist 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 Mekinist, 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. Mekinist may change how other medicines work, and certain combinations of medicine can cause side effects.3

Women who are able to become pregnant should use effective birth control during treatment with Mekinist and for at least four months after the last dose of Tafinlar and Mekinist.1,3

It isn’t known if Mekinist can pass into breast milk. Talk to your doctor if you are breastfeeding or plan to breastfeed. It is recommended that you do not breastfeed during treatment with Mekinist and for at least four months after the last dose of Tafinlar and Mekinist.1,3

Dosing information

Mekinist is available in 0.5 mg and 2 mg tablets. The recommended dose is 2 mg taken by mouth once daily (along with Tafinlar). The medication should be taken at least one hour before or two hours after a meal.1

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

Written by: Emily Downward | Last reviewed: October 2018.
View References
1. Mekinist prescribing information. Available at Accessed 10/3/17. 2. BRAF V600E mutation, National Cancer Institute. Available at Accessed 10/3/17. 3. Taflinlar + Mekinist medication brochure. Available at Accessed 10/3/17.