FDA Approves Selumetinib for Neurofibromatosis Type 1 With Plexiform Neurofibromas
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Selumetinib Is Now Fully Approved for Adults With NF1
The FDA has approved treatment for adults with inoperable plexiform neurofibromas: Selumetinib (Koselugo) . In the KOMET study, the response rate was 4 times higher than with placebo .
On 19 November 2025, the US Food and Drug Administration (FDA) approved treatment for adults with neurofibromatosis type 1 (NF1) and symptomatic, inoperable plexiform neurofibromas (PN): selumetinib (KOSELUGO, AstraZeneca Pharmaceuticals LP) . The FDA had previously approved selumetinib capsules and granules for this indication in pediatric patients aged 1 year and older.
The Disease: Neurofibromatosis Type 1 and PN
Neurofibromatosis Type 1 (NF1) is a genetic disorder that causes tumors to grow throughout the nervous system. Occurring in approximately 30-50% of patients, plexiform neurofibromas (PN)are benign tumors that grow along nerve sheaths, causing pain and disfigurement and potentially compressing vital organs.
In adults, these tumors often cannot be completely removed surgically ("inoperable") because they may encase major nerves or blood vessels. When surgery posed a risk of serious permanent injury, patients were left without a treatment option.
🔬 Mechanism of Action: MEK Inhibition
In NF1, a mutation in the NF1 gene causes overactivation of the RAS/MAPK signaling pathway, leading to uncontrolled cell growth (tumors).
Selumetinibis an oral drug that blocks (inhibits) the MEK1 and MEK2 enzymes, critical components of this pathway. By inhibiting MEK, it interrupts the signal needed for tumor-cell growth, causing tumors to shrink.
The Study Behind the Approval: KOMET (NCT04924608)
The FDA approval is based on the results of the global, randomized, multicenter, double-blind, placebo-controlled KOMET trial. The study enrolled patients aged 18 years and olderwith symptomatic, inoperable PN: 145 patients were randomized 1:1 to selumetinib or placebo.
Key Efficacy Results (End of Cycle 16)
Confirmed response rate in the selumetinib arm (compared with only 5% in the placebo group).
Drug treatment showed statistically significant superiority over placebo.
In 86% of responding patients, the improvement lasted at least 6 months .
Safety and Administration
💊 Recommended Dosage
The recommended adult dose is calculated according to body surface area (BSA):
25 mg/m² (Orally, twice daily).
Treatment continues until disease progression or unacceptable toxicity.
⚠️ Adverse-Effect Management
Adverse effects observed in adults are consistent with the known selumetinib safety profile. Issues requiring attention include:
- Cardiac Effects (Left Ventricular Dysfunction)
- Ocular Toxicity (Blurred Vision)
- Skin Rashes (Dermatitis) and Diarrhea
- Increased bleeding risk and elevated CPK enzyme levels
- FDA. FDA approves selumetinib for adults with neurofibromatosis type 1 with symptomatic, inoperable plexiform neurofibromas. 19 November 2025. [FDA Announcement]
- ClinicalTrials.gov. A Study to Evaluate the Efficacy and Safety of Selumetinib in Adults With NF1 Related Plexiform Neurofibromas (KOMET). NCT04924608. [Clinical Trial Details]
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