Selumetinib

What it is and how it works

Mechanism of Action Selumetinib is an inhibitor of mitogen-activated protein kinase kinases 1 and 2 (MEK1/2). MEK1/2 proteins are upstream regulators of the extracellular signal-related kinase (ERK) pathway. Both MEK and ERK are critical components of the RAS-regulated RAF-MEK-ERK pathway, which is often activated in different types of cancers. In genetically modified mouse models of NF1 that generate neurofibromas that recapitulate the genotype and phenotype of human NF1, oral dosing of selumetinib inhibited ERK phosphorylation, and reduced neurofibroma numbers, volume, and proliferation.

Mechanism class: Mitogen-Activated Protein Kinase Kinase 1 Inhibitors · Mitogen-Activated Protein Kinase Kinase 2 Inhibitors

Indications

is indicated for the treatment of adult and pediatric patients 1 year of age and older with neurofibromatosis type 1 (NF1) who have symptomatic, inoperable plexiform neurofibromas (PN) . KOSELUGO is a kinase inhibitor indicated for the treatment of adult and pediatric patients 1 year of age and older with neurofibromatosis type 1 (NF1) who have symptomatic, inoperable plexiform neurofibromas (PN).

Dosage and administration (summary)

• KOSELUGO capsules: The recommended dosage is 25 mg/m 2 , swallowed whole, taken orally twice daily with or without food (see Table 1) . (2.1 , 2.2 ) • KOSELUGO oral granules: The recommended dosage is equivalent to 25 mg/m 2 , sprinkled onto or mixed with soft food and taken orally twice daily (see Table 2). ( 2.1 , 2.2 ) • Moderate hepatic impairment (Child-Pugh B): The recommended dosage is 20 mg/m 2 orally twice daily (see Tables 6 and 7) . ( 2.2 , 2.4 ) • Severe hepatic impairment (Child-Pugh C): The recommended dosage has not been established.

Contraindications

None. None.

Warnings and precautions

• Left Ventricular Dysfunction : Assess ejection fraction prior to initiating treatment, every 3 months during the first year, then every 6 months thereafter and as clinically indicated. Withhold, reduce the dose, or permanently discontinue KOSELUGO based on severity of adverse reaction. ( 2.3 , 5.1 ) • Ocular Toxicity : Conduct ophthalmic assessments prior to initiating KOSELUGO, at regular intervals during treatment and for new or worsening visual changes. Permanently discontinue KOSELUGO for retinal vein occlusion (RVO).

Pregnancy

Pregnancy Risk Summary Based on findings from animal studies and its mechanism of action , KOSELUGO can cause fetal harm when administered to a pregnant woman. There are no available data on the use of KOSELUGO in pregnant women to evaluate drug-associated risk.

Storage and supply

How Supplied Selumetinib Capsules Strength Description Capsules per Bottle NDC Number 10 mg White to off-white, opaque, hard capsule sealed with a clear band and marked with “SEL 10” in black ink. 60 0310-0610-60 28 0310-0610-28 25 mg Blue, opaque, hard capsule sealed with a clear band and marked with “SEL 25” in black ink.

Source: Selumetinib (Koselugo) — US FDA prescribing information, 2026-05-26, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.