Mekinist (trametinib)

Mekinist® (trametinib) is used to treat certain kinds of advanced melanoma. Mekinist can be used alone or in combination with a drug called Tafinlar® (dabrafenib).1 Mekinist is used to treat melanoma with BRAF V600E or V600K mutation. Your doctor will test for BRAF mutation. Mekinist is not used for melanoma with a normal BRAF gene. It also cannot be used to treat patients who already have been treated with a BRAF inhibitor.

Mekinist is used when the melanoma:1

  • Cannot be removed with surgery (unresectable) or
  • Has spread to distant parts of the body (metastasized)

Mekinist does not come in generic form. Mekinist is similar to Cotellic® (cobimetinib), another drug that is approved to treat unresectable or metastatic melanoma.

How does Mekinist work?

Mekinist is a type of medication called a kinase inhibitor. It works by blocking a protein called MEK that passes along signals for cell growth.

MEK is a protein in a pathway called MAPK (also called ERK). This pathway involves a chain of events that allow cells to grow and survive. Normally, there are mechanisms that turn each protein “on” and “off,” keeping the cell processes under control. However, between 10% and 50% of melanomas have mutations in the gene (instructions) for a protein called BRAF.2 These mutations cause BRAF to stay “on,” sending continuous signals resulting in uncontrolled cell growth.3

MEK comes after BRAF in this chain of events. Mekinist blocks MEK from working and stops the signal from continuing. Mekinist is called a targeted therapy because it targets one feature that makes cancer cells different from normal cells.

Tafinlar is a BRAF inhibitor. When Tafinlar and Mekinist are used together, they target the MAPK pathway at two points. This combination stops or slows the growth of melanomas with BRAF mutations better than either drug alone.1

How effective is Mekinist?

Mekinist was studied alone and together with Tafinlar. All of the patients in these trials had metastatic or unresectable melanoma with BRAF V600 mutations.

Mekinist Alone. Patients who had never been treated with chemotherapy or had only had one chemotherapy treatment were studied in a trial. People who had been treated with a BRAF inhibitor or MEK inhibitor were not allow to participate. Overall, 22% responded to treatment with Mekinist.1 “Response” has to do with whether the tumor shrinks or grows more slowly while on treatment. Response is only about tumor changes and it does not measure whether you—as a whole patient—have improved. Response is also different from survival. Response to treatment can be partial or complete. In this trial, 2% had a complete response and 20% had a partial response. The response lasted a median of 5.5 months.

Progression-free survival is how long a person survives after treatment without the cancer getting worse. The median progression-free survival in this study was 4.8 months.1

Mekinist plus Tafinlar. Another study compared Tafinlar plus Mekinist with dabrafeninb alone. Combination therapy resulted in:1

  • Greater response to treatment
  • Fewer deaths
  • Longer overall survival
  • Slightly fewer people with cancer progression
  • Slightly longer time until cancer progression

In this trial, 66% of people had a response to treatment with Tafinlar plus Mekinist. The median progression-free survival for patients receiving combination treatment was about 9 months. Median overall survival was 25 months.1

How do I take Mekinist?

Before taking Mekinist, read the Medication Guide that comes in the package. Follow your doctor’s instructions for taking Mekinist.

Mekinist comes as a tablet that is taken by mouth. Take Mekinist once per day at the same time each day. Take Mekinist at least 1 hour before or 2 hours after a meal.

You will continue taking Mekinist until the cancer progresses or the side effects are unacceptable.1

What are the side effects of Mekinist?

Taking Mekinist with Tafinlar can cause other cancers.1 This combination has been linked to other types of skin cancer such as squamous cell carcinoma, and basal cell carcinoma. Possible signs of new cancers include: new wart, skin sore, reddish bump, or mole that changes in size or color.

The most common side effects of Mekinist alone are diarrhea and swelling in the face, arms, or legs. Additional side effects when Mekinist is used with Tafinlar are:1

  • Nausea and vomiting
  • Chills
  • High blood pressure
  • Rash

Less common but serious side effects of Mekinist are:1

  • Bleeding problems in the brain or stomach
  • Blood clots
  • Heart problems
  • Eye problems
  • Fever
  • Severe skin reaction
  • Increased blood sugar

Mekinist may make it difficult to get pregnant. If this is a concern for you, discuss this with your doctor.

Who should not take Mekinist?

People who have previously been treated with a BRAF inhibitor for melanoma should not take Mekinist.1

Pregnant women should not take Mekinist.1 Women who could become pregnant should use birth control during treatment. Continue using birth control for at least 4 months after the last dose of Mekinist. Do not breastfeed while taking Mekinist. Do not breastfeed for 4 months after your last dose of Mekinist.

Tell your doctor about any medical conditions you have, especially:

  • Bleeding problems
  • Problems with blood clots
  • Heart problems
  • Eye problems
  • Lung or breathing problems
  • High blood pressure
  • Liver or kidney problems

What precautions are needed when taking Mekinist?

You will need regular skin exams while taking Mekinist with Tafinlar.1 Your doctor will do a skin exam before you start these medications. You will need skin exams every 2 months while taking these medications and for up to 6 months afterward. Your doctor will also look for non-skin cancers.

During treatment and for at least 4 months after the last dose of Mekinist:1

  • Women who can become pregnant should use birth control.
  • Women should not breastfeed.
Written by: Sarah O'Brien | Last reviewed: May 2017.
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