KOSELUGO

Indications and Usage ( 1 ) 11/2025 Dosage and Administration ( 2.1 ) 11/2025 Warnings and Precautions ( 5.2 ) 05/2026 Warnings and Precautions ( 5.4 , 5.5 , 5.7 ) 11/2025

1 INDICATIONS AND USAGE KOSELUGO 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) [see Dosage and Administration (2) ]. 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). ( 1 )

2 DOSAGE AND ADMINISTRATION • 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. ( 2.4 , 8.6 ) • Strong or Moderate CYP3A4 Inhibitors or Fluconazole: If coadministration with strong or moderate CYP3A4 inhibitors or fluconazole cannot be avoided, reduce the dose of KOSELUGO (see Tables 8 and 9) . ( 2.5 ) 2.1 Recommended Dosage The recommended dosage of KOSELUGO capsules ( see Table 1 ) and KOSELUGO oral granules ( see Table 2 ) for adult and pediatric patients 1 year of age and older, based on body surface area, is 25 mg/m 2 orally twice daily, until disease progression or unacceptable toxicity [see Dosage and Administration (2.2)]. Table 1 Recommended Dosage: KOSELUGO Capsules Body Surface Area The recommended dosage of KOSELUGO capsules for patients with a BSA less than 0.55 m 2 has not been established. KOSELUGO Capsules 0.55 – 0.69 m 2 20 mg in the morning and 10 mg in the evening 0.70 – 0.89 m 2 20 mg twice daily 0.90 – 1.09 m 2 25 mg twice daily 1.10 – 1.29 m 2 30 mg twice daily 1.30 – 1.49 m 2 35 mg twice daily 1.50 – 1.69 m 2 40 mg twice daily 1.70 – 1.89 m 2 45 mg twice daily ≥ 1.90 m 2 50 mg twice daily Table 2 Recommended Dosage: KOSELUGO Oral Granules Body Surface Area The recommended dosage of KOSELUGO oral granules for patients with a BSA less than 0.40 m 2 has not been established. KOSELUGO Oral Granules 0.40 – 0.59 m 2 12.5 mg twice daily 0.60 – 0.69 m 2 15 mg twice daily 0.70 – 0.89 m 2 20 mg twice daily 0.90 – 1.09 m 2 25 mg twice daily 1.10 – 1.29 m 2 30 mg twice daily 1.30 – 1.49 m 2 35 mg twice daily 1.50 – 1.69 m 2 40 mg twice daily 1.70 – 1.89 m 2 45 mg twice daily ≥ 1.90 m 2 50 mg twice daily 2.2 Administration KOSELUGO is available in two dosage forms: KOSELUGO capsules and KOSELUGO oral granules. Prescribe KOSELUGO oral granules for patients who have difficulty swallowing whole capsules. KOSELUGO Capsules • Administer KOSELUGO capsules to patients who can swallow a whole capsule. • Swallow KOSELUGO capsules whole. Do not open, chew or crush KOSELUGO capsules. • KOSELUGO capsules may be administered with or without food. KOSELUGO Oral Granules Administer KOSELUGO oral granules to patients who have difficulty swallowing a whole capsule. Sprinkle KOSELUGO oral granules on or mix with a small amount (about 1 to 3 teaspoons) of smooth yogurt, or fruit puree containing the following fruits: apple, banana, pear, or strawberry and consume within 30 minutes of preparation. If not consumed within 30 minutes of preparation, discard and prepare a new dose. If a dose has been partially consumed within 30 minutes of preparation, discard the remainder of the dose and do not prepare a new dose, aim to complete dosing within 30 minutes next time. The KOSELUGO oral granules should be free-flowing. Do NOT use if the oral granules are clumped or stuck inside the capsule shell. Instruct the patient or caregiver to contact their pharmacy if this happens. Discard the empty capsule shells after use. Do NOT swallow, chew, or dissolve the capsule shells of KOSELUGO oral granules. Do NOT chew or crush the KOSELUGO oral granules. Do NOT add oral granules to liquids. Do NOT mix KOSELUGO oral granules in grapefruit or any juice, fruit puree or jam containing Seville orange. Missed Dose If a dose of KOSELUGO capsules or KOSELUGO oral granules is missed, make up that dose unless the next dose is due within 6 hours. Vomiting If vomiting occurs after taking a dose of KOSELUGO capsules or KOSELUGO oral granules, do not take an additional dose …

3 DOSAGE FORMS AND STRENGTHS Capsules: • 10 mg selumetinib: white to off-white, opaque, hard capsule sealed with a clear band and marked with “SEL 10” in black ink. • 25 mg selumetinib: blue, opaque, hard capsule sealed with a clear band and marked with “SEL 25” in black ink. Oral Granules: • 5 mg selumetinib: off-white to light-yellow free-flowing oral granules contained within capsules. The capsules have a yellow cap and white body. The cap is printed with “sel 5” in black ink, and body is printed with a sprinkle capsule image indicating opening. • 7.5 mg selumetinib: off-white to light-yellow free-flowing oral granules contained within capsules. The capsules have a pink cap and white body. The cap is printed with “sel 7.5” in black ink, and body is printed with a sprinkle capsule image indicating opening. • Capsules: 10 mg and 25 mg of selumetinib. ( 3 ) • Oral Granules: 5 mg and 7.5 mg of selumetinib. ( 3 )

4 CONTRAINDICATIONS None. None. ( 4 )

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: • Left Ventricular Dysfunction [see Warnings and Precautions (5.1) ] • Ocular Toxicity [see Warnings and Precautions (5.2) ] • Gastrointestinal Toxicity [see Warnings and Precautions (5.3) ] • Skin Toxicity [see Warnings and Precautions (5.4) ] • Increased Creatine Phosphokinase [see Warnings and Precautions (5.5) ] Most common adverse reactions in pediatric patients (≥ 40%) are: vomiting, diarrhea, increased creatine phosphokinase, dry skin, paronychia, nausea, dermatitis acneiform, and pyrexia. ( 6.1 ) Most common adverse reactions in adult patients (≥ 40%) are rash (all), dermatitis acneiform, and diarrhea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact AstraZeneca 1-800-236-9933 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The NF1 PN pediatric safety pool described in the WARNINGS AND PRECAUTIONS reflects exposure to KOSELUGO at the recommended dosage in 134 pediatric patients in SPRINKLE (N = 36) (NCT05309668), SPRINT Phase I (N = 24) (NCT01362803), SPRINT Phase II Stratum 1 (N = 50) [see Clinical Studies (14.1) ] , and Phase I Food Effect Study (N = 24) (NCT05101148). Among pediatric patients, the duration of KOSELUGO exposure was 12 months or longer (80%), more than 2 years (44%), or more than 3 years (37%). The most common adverse reactions in pediatric patients (≥ 40%) are vomiting, diarrhea, increased creatine phosphokinase, dry skin, paronychia, nausea, dermatitis acneiform, and pyrexia. In the KOMET adult NF1 PN study, 71 adult patients received KOSELUGO at the recommended dosage [see Clinical Studies (14.1) ] . Among adult patients, the duration of KOSELUGO exposure in the randomized period was 6 months or longer (92%), and 11 months or longer (66%). The most common adverse reactions in adult patients (≥ 40%) are rash (all), dermatitis acneiform, and diarrhea. Neurofibromatosis Type 1 (NF1) with Inoperable Plexiform Neurofibromas (PN) Pediatrics 2-18 years of Age (SPRINT Phase II Stratum 1) The safety of KOSELUGO was evaluated in SPRINT Phase II Stratum 1 [see Clinical Studies (14.1) ] . Eligible patients were 2-18 years of age with neurofibromatosis type 1 (NF1) who had inoperable plexiform neurofibromas (PN) that was causing significant morbidity. Patients were excluded for abnormal LVEF, uncontrolled hypertension (blood pressure ≥ the 95th percentile for age, height, and sex), any current or past history of RVO or RPED, intraocular pressure > 21 mmHg (or upper limit of normal adjusted by age), uncontrolled glaucoma, and inability to swallow whole capsules. Patients received KOSELUGO 25 mg/m 2 orally twice daily (N = 50). Among these patients, 88% were exposed for 12 months or longer and 66% were exposed for greater than 2 years. Serious adverse reactions occurred in 24% of patients who received KOSELUGO. Serious adverse reactions that occurred in 2 or more patients were anemia, hypoxia and diarrhea. Permanent discontinuation due to an adverse reaction occurred in 12% of patients who received KOSELUGO. Adverse reactions resulting in permanent discontinuation of KOSELUGO included increased blood creatinine, increased weight, diarrhea, paronychia, malignant peripheral nerve sheath tumor, acute kidney injury, and skin ulcer. Dosage interruptions and dose reductions due to adverse reactions occurred in 80% and 24% of patients who received KOSELUGO, respectively. Adverse reactions requiring a dosage interruption or reduction in ≥ 5% of patients were vomiting, paronychia, diarrhea, nausea, abdominal pain, rash, skin infection, influenza-like illness, pyrexia and weight gain. The most common adverse rea …

7 DRUG INTERACTIONS • Strong or Moderate CYP3A4 Inhibitors or Fluconazole : Avoid coadministration of strong or moderate CYP3A4 inhibitors or fluconazole with KOSELUGO. If coadministration cannot be avoided, reduce the dose of KOSELUGO. ( 2.5 , 7.1 ) • Strong or Moderate CYP3A4 Inducers : Avoid concomitant use of strong and moderate CYP3A4 inducers. ( 7.1 ) 7.1 Effect of Other Drugs on KOSELUGO Strong or Moderate CYP3A4 Inhibitors or Fluconazole Management • Avoid concomitant use of strong or moderate CYP3A4 inhibitors or fluconazole with KOSELUGO. If coadministration with strong or moderate CYP3A4 inhibitors or fluconazole cannot be avoided, reduce KOSELUGO dosage [see Dosage Modifications for Drug Interactions (2.5) ]. Clinical Impact • Concomitant use of KOSELUGO with a strong or moderate CYP3A4 inhibitor or fluconazole increased selumetinib plasma concentrations [see Clinical Pharmacology (12.3) ] , which may increase the risk of adverse reactions. Strong or Moderate CYP3A4 Inducers Management • Avoid concomitant use of strong or moderate CYP3A4 inducers with KOSELUGO. Clinical Impact • Concomitant use of KOSELUGO with a strong or moderate CYP3A4 inducer decreased selumetinib plasma concentrations [see Clinical Pharmacology (12.3) ] , which may reduce KOSELUGO efficacy. Vitamin E Management • Supplemental vitamin E is not recommended if daily vitamin E intake (including the amount of vitamin E in KOSELUGO capsules and supplement) will exceed the recommended or safe limits. • Monitor for bleeding in patients administered a vitamin‐K antagonist or an anti‐platelet agent with KOSELUGO capsules. Increase INR monitoring, as appropriate, in patients taking a vitamin‐K antagonist [see Warnings and Precautions (5.3) ] . Clinical Impact • KOSELUGO capsules contain vitamin E and daily vitamin E intake that exceeds the recommended or safe limits may increase the risk of bleeding. An increased risk of bleeding may occur in patients taking a vitamin‐K antagonist or an anti‐platelet agent with KOSELUGO capsules.

8 USE IN SPECIFIC POPULATIONS • Lactation: Advise not to breastfeed. (8.2) 8.1 Pregnancy Risk Summary Based on findings from animal studies and its mechanism of action [see Clinical Pharmacology (12.1) ] , 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. In animal reproduction studies, administration of selumetinib to mice during organogenesis caused reduced fetal weight, adverse structural defects, and effects on embryofetal survival at exposures approximately > 5 times the human exposure at the clinical dose of 25 mg/m 2 twice daily ( see Data ). Advise pregnant women of the potential risk to the fetus. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Human Data In KOMET, a first trimester spontaneous abortion was reported in a patient receiving KOSELUGO. Animal Data In embryo-fetal development studies in mice at doses > 2.5 mg/kg twice daily (~5-times the human exposure based on area under the curve [AUC] at the clinical dose of 25 mg/m 2 twice daily), selumetinib caused increases in post-implantation loss, a reduction in mean fetal and litter weights, and an increased occurrence of open eye and cleft palate, but did not induce significant maternal toxicity. Administration of selumetinib to pregnant mice from gestation Day 6 through lactation Day 20 resulted in reduced pup body weights and fewer pups met the pupil constriction criterion on day 21 post-partum. The incidence of malformations (e.g., prematurely open eye(s) and cleft palate) was increased even at the lowest dose of 0.5 mg/kg twice daily (maternal maximal concentration [C max ] of ~0.6 times the human C max at the clinical dose of 25 mg/m 2 twice daily). 8.2 Lactation Risk Summary There are no data on the presence of selumetinib or its active metabolite in human milk or their effects on the breastfed child or milk production. Selumetinib and its active metabolite were present in the milk of lactating mice ( see Data ). Due to the potential for adverse reactions in a breastfed child, advise women not to breastfeed during treatment with KOSELUGO and for 1 week after the last dose. Data Animal Data Selumetinib and its active metabolite were present in milk from mice dosed with selumetinib throughout gestation and lactation, with a mean plasma/milk ratio of 1.5 in lactating dams dosed at 5 mg/kg twice daily. Administration of selumetinib to dams during gestation and early lactation was associated with adverse events in pups, including reduced growth rates and incidence of malformations [see Use in Specific Populations (8.1) ]. 8.3 Females and Males of Reproductive Potential KOSELUGO can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1) ] . Pregnancy Testing Verify the pregnancy status of females of reproductive potential prior to initiating KOSELUGO [see Use in Specific Populations (8.1) ] . Contraception Females Advise females of reproductive potential to use effective contraception during treatment and for 1 week after the last dose. Males Advise male patients with female partners of reproductive potential to use effective contraception during treatment with KOSELUGO and for 1 week after the last dose. 8.4 Pediatric Use The safety and effectiveness have been established in pediatric patients 1 year of age and older with NF1 who have inoperable PN and the information on this use is discussed throughout the labeling. The safety and effectiveness of KOSELUGO have not been established in pediatric patients younger than 1 year of age. Animal Toxicity Data In 3-month general toxicology studies, male rats receiving selumetinib at doses ≥ 10 mg/kg daily (~60-times the human exposure based on AUC at the clinical dose of 25 mg/m 2 twice daily) showed growth plate dysplasia. 8. …

12.1 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.

11 DESCRIPTION KOSELUGO contains selumetinib sulfate, a kinase inhibitor. The chemical name is 5-[(4-bromo-2-chlorophenyl)amino]-4-fluoro-6-[(2-hydroxyethoxy)carbamoyl]-1-methyl-1 H -benzimidazol-3-ium hydrogen sulfate. The molecular formula for selumetinib sulfate is C 17 H 17 BrClFN 4 O 7 S and the relative molecular mass is 555.76 g/mol. Selumetinib sulfate has the following structural formula: Selumetinib sulfate is a white to yellow monomorphic crystalline powder that exhibits a pH dependent solubility. Selumetinib sulfate is freely soluble at pH 3. Selumetinib sulfate has two ionizable functions with pKa values of 2.8 and 8.4. KOSELUGO (selumetinib) 10 mg capsules for oral use, contain 10 mg selumetinib (equivalent to 12.1 mg selumetinib sulfate) and the excipient, vitamin E polyethylene glycol succinate. The capsule shell contains carnauba wax, carrageenan, hypromellose, potassium chloride, purified water, and titanium dioxide. The capsule is imprinted with black ink that contains ammonium hydroxide, iron oxide black, propylene glycol, and shellac. KOSELUGO (selumetinib) 25 mg capsules for oral use, contain 25 mg selumetinib (equivalent to 30.25 mg selumetinib sulfate) and the excipient, vitamin E polyethylene glycol succinate. The capsule shell contains carnauba wax and/or cornstarch, carrageenan, FD&C blue 2, ferric oxide yellow, hypromellose, potassium chloride, purified water, and titanium dioxide. The capsule is imprinted with black ink that contains carnauba wax, FD&C Blue 2 aluminum lake, ferric oxide red, ferric oxide yellow, glyceryl monooleate, and shellac. KOSELUGO (selumetinib) 5 mg oral granules contain 5 mg selumetinib (equivalent to 6.05 mg selumetinib sulfate). The uncoated cores contain selumetinib sulfate, glyceryl dibehenate, and stearoyl polyoxylglycerides. The granule coating contains acetone, hypromellose acetate succinate, and stearic acid. The capsule shell contains ferric oxide yellow, hypromellose, and titanium dioxide. The capsule shell is imprinted with black ink that contains butyl alcohol, dehydrated alcohol, ferric oxide black, isopropyl alcohol, potassium hydroxide, propylene glycol, purified water, shellac, and strong ammonia solution. KOSELUGO (selumetinib) 7.5 mg oral granules contain 7.5 mg selumetinib (equivalent to 9.08 mg selumetinib sulfate). The uncoated cores contain selumetinib sulfate, glyceryl dibehenate, and stearoyl polyoxylglycerides. The granule coating contains acetone, hypromellose acetate succinate, and stearic acid. The capsule shell contains ferric oxide red, hypromellose, and titanium dioxide. The capsule shell is imprinted with black ink that contains butyl alcohol, dehydrated alcohol, ferric oxide black, isopropyl alcohol, potassium hydroxide, propylene glycol, purified water, shellac, and strong ammonia solution. structure

10 OVERDOSAGE Dialysis is not effective as KOSELUGO is highly protein bound and is extensively metabolized.

16 HOW SUPPLIED/STORAGE AND HANDLING 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. 60 0310-0625-60 28 0310-0625-28 Selumetinib Oral Granules Strength Description Capsules per Bottle NDC Number 5 mg Off‐white to light‐yellow free‐flowing oral granules contained within capsules. The capsules have a yellow cap and white body. The cap is printed with “sel 5” in black ink, and body is printed with a sprinkle capsule image indicating opening. 60 0310‐0635‐60 7.5 mg Off‐white to light‐yellow free‐flowing oral granules contained within capsules. The capsules have a pink cap and white body where the cap is printed with “sel 7.5” in black ink, and body is printed with a sprinkle capsule image indicating opening. 60 0310‐0640‐60 Storage KOSELUGO Capsules Store KOSELUGO capsules at 20°C to 25°C (68°F to 77°F) with excursions permitted to 15°C to 30°C (59°F to 86°F) [see USP Controlled Room Temperature]. Dispense and store in the original bottle to protect from light and moisture. Do not remove desiccant. Keep the bottle tightly closed after first opening. KOSELUGO Oral Granules Store and transport KOSELUGO oral granules refrigerated at 2°C to 8°C (36°F to 46°F). After receipt, patients may store at room temperature 20°C to 25°C (68°F to 77°F). Do NOT exceed 30°C (86°F). KOSELUGO oral granules may clump together or stick to the capsule shell if exposed to high temperatures, which may lead to underdose. Dispense and store in the original bottle to protect from light and moisture. Do not remove desiccant. Keep the bottle tightly closed after first opening.