Selumetinib
Koselugo (selumetinib) is a prescription MEK inhibitor used to treat pediatric patients with neurofibromatosis type 1 (NF1) who have symptomatic, inoperable plexiform neurofibromas. It is the first FDA-approved drug specifically for this rare genetic condition affecting nerve tissue tumors. The medication is taken orally in capsule form.
Koselugo is a targeted therapy for children with NF1-related inoperable plexiform neurofibromas, working by blocking MEK enzymes involved in tumor growth.
Key facts at a glance
- RxNorm
- 2289419
- Generic
- Koselugo
- Class
- brand-name
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Koselugo is indicated for pediatric patients 2 years and older with neurofibromatosis type 1 (NF1) who have symptomatic, inoperable plexiform neurofibromas. NF1 is a rare genetic disorder that causes tumors to form on nerve tissue throughout the body.
Koselugo is a selective MEK 1/2 inhibitor. It blocks the activity of MEK enzymes in the RAS/MAPK pathway, which plays a key role in cell growth and division. By inhibiting this pathway, the medication helps reduce tumor size and associated symptoms in patients with NF1-related plexiform neurofibromas.
Common side effects include skin rash, diarrhea, nausea, vomiting, and muscle pain. Patients should be monitored for cardiac events and ocular issues. Koselugo may cause fetal harm and should not be used during pregnancy. It is typically used under the supervision of specialists familiar with NF1 management.
Official drug label
WellAlly may earn a referral fee from linked resources at no extra cost to you. Editorial content is never influenced by commercial relationships.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy