Mirdametinib

Brand name: Gomekli
Dosage form: tablets (1mg), capsules (1mg, 2mg)
Drug class: Multikinase inhibitors

Medically reviewed by Melisa Puckey, BPharm. Last updated on Feb 23, 2025.

What is Mirdametinib?

Mirdametinib (Gomekli) is an FDA-approved medication used to treat neurofibromatosis type 1 (NF1) with plexiform neurofibromas causing symptoms, that cannot be surgically removed. Mirdametinib helps to reduce tumor size, relieve symptoms, and improve quality of life. Mirdametinib can be used by adults and patients 2 years and older. Neurofibromatosis type 1 with plexiform neurofibromas is often shortened to NF1-PN.

Mirdametinib's brand name is Gomekli by SpringWorks Therapeutics. Mirdametinib is from the drug class MEK inhibitors. 

Mirdametinib mechanism of action is by inhibiting proteins MEK1 and MEK2 which are part of the messenger system that controls cell growth and division.  Inhibiting MEK proteins controls cell division and helps slow cancer growth.

Mirdametinib FDA approval was received for treatment of neurofibromatosis type 1 (NF1) in adults and pediatric patients (2 years and older) who have symptomatic plexiform neurofibromas (PN) that are not able to be completely removed by surgery. Mirdametinib FDA approval was granted to SpringWorks Therapeutics on February 11, 2025, after positive results from the Phase 2b ReNeu trial (NCT03962543).

Mirdametinib (Gomekli) tablets (1mg) are taken twice daily, they can be swallowed whole or maybe dispersed in drinking water and taken orally as a liquid. 

What is Neurofibromatosis Type 1?

Neurofibromatosis Type 1 (NF1) is a rare genetic disorder due to a mutation in the NF1 gene. The NF1 gene has a role in signaling cells cell growth and survival, and when there is a mutation this causes excessive cell growth which results in tumors. 

NF1 patients have tumors called plexiform neurofibromas (PN), that grow along the peripheral nerve sheath and can cause severe disfigurement, pain, and functional impairment. Often the plexiform neurofibromas are unable to be surgically removed due to the infiltrative tumor growth pattern along nerves. These plexiform neurofibromas have the potential to become malignant peripheral nerve sheath tumors, which can be aggressive and potentially fatal.

How well does Mirdametinib work?

In the clinical trial ReNeu (Phase 2b ReNeu trial) Mirdametinib ’s efficacy was determined by its confirmed overall response rate (ORR), measured by a blinded independent central review using volumetric MRI analysis. The results from the ReNeu trial demonstrated that mirdametinib had:

• 41% overall response rate* in adults 
• 52% overall response rate* in pediatric patients 
• Tumor volume reductions were deep and durable, with a median best percentage change of -41% in adults and -42% in children
• 88% of adults and 90% of children who achieved a confirmed response maintained that response for at least 12 months
• 50% of adults and 48% of children had a response lasting 24 months or longer

Additionally, patients experienced early and sustained improvements in pain and quality of life, as assessed across multiple patient-reported outcome tools.

*Overall response rate (ORR) is the percentage of patients who achieve either a complete response (disappearance of the target tumor) or a partial response (a 20% or greater reduction in tumor size). 

Mirdametinib side effects

Common mirdametinib side effects

Common adult mirdametinib side effects included:

• Rash (90%)
• Diarrhea (59%)
• Nausea (52%)
• Muscle and joint pain (41%)
• Vomiting (38%)
• Tiredness or fatigue (29%)
• COVID-19 (22%)
• Peripheral neuropathy (21%)

The most common laboratory abnormalities in Grade 3 or 4 (>2%) were decreased neutrophil count and increased creatine phosphokinase.

Common pediatric mirdametinib side effects included:

• Rash (73%)
• Diarrhea (55%)
• Muscle and joint pain (41%)
• Abdominal pain (39%) 
• Vomiting (39%)
• Headache (34%)
• Paronychia (32%)
• Left ventricular dysfunction (27%),
• Nausea (27%).
• Mouth ulcers (20%)
• Fever (20%)
• COVID 19 (10%)
• Upper respiratory tract infection - URTI (23%)

The most common Grade 3 or 4 laboratory abnormalities (>2%) were decreased neutrophil count and increased creatine phosphokinase.

These side effects occurred in patients in the Phase 2b ReNeu clinical trial.

Serious side effects and warnings

Mirdametinib carries significant safety warnings, including:

• Ocular Toxicity: May cause retinal vein occlusion (RVO), retinal pigment epithelium detachment (RPED), and blurred vision. Ophthalmic assessments are required before and during treatment.
• Left Ventricular Dysfunction: Gomekli can lead to decreased ejection fraction, with echocardiography recommended for starting treatment, every 3 months for the first year and then as often as directed. 
• Dermatologic Adverse Reactions: Rash and other skin-related issues were common, requiring supportive care and potential dose adjustments, or stopping of treatment.
• Embryo-Fetal Toxicity: Gomekli may cause fetal harm; pregnancy status must be verified before starting treatment. Effective contraception is recommended for patients of reproductive potential.

These are not all of the possible side effects of GOMEKLI. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088

Related/similar drugs

Before taking this medicine.

Tell your healthcare provider about all of your medical conditions, including if you:

• have eye problems
• have heart problems
• are pregnant or plan to become pregnant as Gomekli can harm your unborn baby.

Pregnancy

Females who are able to become pregnant:

• You should have a pregnancy test to confirm you are not pregnant before starting treatment with this medicine.
• Use effective birth control (contraception) during treatment and for 6 weeks after your last dose.
• Tell your healthcare provider right away if you become pregnant or think you may be pregnant during treatment

Males with female partners who are able to become pregnant:

• Use effective birth control (contraception) during treatment with Gomekli and for 3 months after your last dose.
• Tell your healthcare provider right away if your female partner becomes pregnant or thinks she may be pregnant during treatment or within the 3 months after stopping treatment with this medicine.

Breastfeeding

• Tell your healthcare provider if you are breastfeeding or plan to breastfeed, as it is not known if Gomekli passes into your breastmilk.
• Do not breastfeed during treatment with GOMEKLI and for 1 week after your last dose.
• Talk to your healthcare provider about the best way to feed your baby during this time.

How should I take mirdametinib?

• Gomekli is taken twice a day, about 12 hours apart, for 21 days, followed by 7 days off treatment, to complete a 28-day treatment cycle. Your healthcare provider will decide how many treatment cycles are right for you.
• Gomekli can be taken with or without food.
• Gomekli is available as capsules and tablets for oral suspension.

How to take mirdametinib capsules:

• Swallow each capsule whole with drinking water. If more than 1 capsule is required, swallow 1 capsule at a time
• You should not open, break, or chew the capsules

How to take mirdametinib tablets

• You can swallow each tablet for oral suspension whole with drinking water. If more than 1 tablet is required, swallow 1 tablet at a time.
• You can disperse the tablets for oral suspension in drinking water to make a liquid (suspension) that you swallow. See full directions on how to prepare and take Gomekli as an oral suspension.

 Take mirdametinib exactly as your healthcare provider tells you to take it. Your healthcare provider may change your dose, temporarily stop, or permanently stop treatment with mirdametinib if you develop certain side effects.

Your healthcare provider will decide how many treatment cycles are right for you.

Mirdametinib dosing information 

Mirdametinib recommended dosage is 2 mg/m2 orally twice daily (approximately every 12 hours) with or without food for the first 21 days of each 28-day cycle.

• The dose may be reduced due to adverse reactions.
• The maximum dose is 4 mg twice daily. 

Gomekli SpringWorks CareConnections

SpringWorks Therapeutics has established SpringWorks CareConnections™, a support program for  NF1-PN patients prescribed Gomekli (mirdametinib), offering assistance with insurance coverage, financial support, and educational resources. Gomekli is expected to be available in the United States through a specialty pharmacy and distributor network.

What happens if I miss a dose?

If you miss a dose of your tablets or capsules, skip the missed dose and take your next dose at your regularly scheduled time.

If you vomit at any time after taking your dose, do not take an additional dose. Take your next dose at your regularly scheduled time.

What other drugs will affect this medicine?

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. This list of interactions is not complete. 

Mirdametinib Package Insert

Review the Mirdametinib Package Insert (Gomekli) for more detailed information about this medicine. The Gomekli Package Insert contains more comprehensive information on Indications and Usage, Dosage and Administration, Clinical Pharmacology, Clinical Studies, Drug Interaction, and more. Discuss any medical questions you have with your doctor or other health care provider. This is not all the information you need to know about this medicine for safe and effective use, and it does not take the place of talking to your doctor about your treatment.

The Package Insert is sometimes called Mirdametinib Prescribing Information (PI) or the FDA label.

Ingredients 

Active ingredient 

• mirdametinib

Inactive ingredients 

Gomekli Capsules (1 mg and 2 mg) gelatin capsule

• Croscarmellose sodium, magnesium stearate, and microcrystalline cellulose. 
• The gelatin capsule shell contains FD&C blue #1, gelatin, titanium dioxide, and yellow iron oxide. The capsule is imprinted with white ink that contains butyl alcohol, dehydrated alcohol, isopropyl alcohol, potassium hydroxide, propylene glycol, purified water, shellac, strong ammonia solution, and titanium dioxide.

Gomekli Tablets 1 mg tablets for oral suspension 

• Croscarmellose sodium, magnesium stearate, microcrystalline cellulose, grape flavor, and sucralose. The grape flavor includes corn syrup solids, modified corn starch, and triacetin. 

Company 

Govmekli  SpringWorks Therapeutics, Inc. 

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer