LEQEMBI

Dosage and Administration ( 2.5 ) 8/2025 Dosage and Administration ( 2.2 , 2.3 , 2.4 , 2.6 , 2.7 ) 7/2026 Contraindications ( 4 ) 8/2025 Warnings and Precautions ( 5.1 ) 12/2025 Warnings and Precautions ( 5.2 , 5.3 ) 8/2025

1 INDICATIONS AND USAGE LEQEMBI is indicated for the treatment of Alzheimer’s disease. Treatment with LEQEMBI should be initiated in patients with mild cognitive impairment or mild dementia stage of disease, the population in which treatment was initiated in clinical trials. LEQEMBI is an amyloid beta-directed antibody indicated for the treatment of Alzheimer’s disease. Treatment with LEQEMBI should be initiated in patients with mild cognitive impairment or mild dementia stage of disease, the population in which treatment was initiated in clinical trials. ( 1 )

2 DOSAGE AND ADMINISTRATION Confirm the presence of amyloid beta pathology prior to initiating treatment. ( 2.1 ) Obtain a recent baseline brain MRI prior to initiating treatment. ( 2.4 , 5.1 ) Obtain an MRI after 1, 2, 3, and 6 months of treatment. If radiographically observed ARIA occurs, treatment recommendations are based on type, severity, and presence of symptoms. ( 2.4 , 5.1 ) Recommended starting dosage: Intravenous infusion: 10 mg/kg once every 2 weeks administered after dilution as an intravenous infusion over approximately one hour. ( 2.2 , 2.5 ) Subcutaneous injection: 500 mg administered once a week using the LEQEMBI IQLIK autoinjector. ( 2.2 , 2.6 ). After 18 months, continue treatment with the starting dosage or transition to an intravenous or subcutaneous maintenance dosage. (2.2) Recommended maintenance dosage: Intravenous infusion: 10 mg/kg once every 4 weeks ( 2.2 , 2.5 ) Subcutaneous injection: 360 mg administered once a week using the LEQEMBI IQLIK autoinjector ( 2.2 , 2.6 ). See Full Prescribing Information for preparation and administration instructions. ( 2.5 , 2.6 ) 2.1 Patient Selection Confirm the presence of amyloid beta pathology prior to initiating treatment [see Clinical Pharmacology ( 12.1 )] . 2.2 Recommended Dosage Initiate LEQEMBI using a starting dosage regimen (see Table 1 ). After 18 months, the starting dosage regimen may be continued or a transition to a maintenance dosage regimen may be considered (see Table 2 ). Both the starting and maintenance dosage regimens can be administered by either intravenous infusion or subcutaneous injection. The route of administration can be switched. When switching the route of administration and simultaneously transitioning from the starting dosage regimen to the maintenance dosage regimen, see Table 2. When switching the route of administration during the starting dosage regimen or during the maintenance dosage regimen, see Dosage and Administration ( 2.3 ). Table 1: Starting Dosage Regimen Route of Administration Dose Frequency Infusion Rate (if i ntravenous) Intravenous (LEQEMBI) 10 mg/kg Once every 2 weeks Over approximately one hour Subcutaneous (LEQEMBI IQLIK) 500 mg (two 250 mg injections) Once every week ------------------------ Table 2: Maintenance Dosage Regimen Route of Administration Dose Frequency Infusion Rate (if intravenous) Time Interval Between Last Starting Dose and First Maintenance Dose Intravenous (LEQEMBI) 10 mg/kg Once every 4 weeks Over approximately one hour If previously on intravenous starting dosage regimen: 2 weeks If previously on subcutaneous starting dosage regimen: minimum of 2 weeks, but no more than 3 weeks Subcutaneous (LEQEMBI IQLIK) 360 mg Once every week — 1 week (regardless of starting dosage regimen) For intravenous infusion, use LEQEMBI vials. LEQEMBI vials must be diluted before administration [see Dosage and Administration ( 2.5 )]. For subcutaneous administration, use LEQEMBI IQLIK [see Dosage and Administration ( 2.6 )]. 2.3 Switching Routes of Administration During the Starting Dosage Regimen or During the Maintenance Dosage Regimen During the starting dosage regimen and maintenance dosage regimen, the route of administration (intravenous with LEQEMBI vials or subcutaneous with LEQEMBI IQLIK) may be switched as described below. Thereafter follow the dosing schedule for the new route of administration. Switching Routes of Administration During the Starting Dosage Regimen • To switch from the intravenous to subcutaneous route of administration, administer the first subcutaneous dose 1 week after the last intravenous dose. • To switch from the subcutaneous to the intravenous route of administration, administer the first intravenous dose a minimum of 2 weeks, but no more than 3 weeks, after the last subcutaneous dose. Switching Routes of Administration During the Maintenance Dosage Regimen • To switch from the intravenous to subcutaneous route of administration, administer the first subcutaneous dose 1 week af …

3 DOSAGE FORMS AND STRENGTHS Lecanemab-irmb is a clear to very opalescent, colorless to pale yellow solution, available as: Intravenous Infusion Injection: 500 mg/5 mL (100 mg/mL) in a single-dose vial Injection: 200 mg/2 mL (100 mg/mL) in a single-dose vial Subcutaneous Injection Injection: 250 mg/1.25 mL (200 mg/mL) in a single-dose prefilled LEQEMBI IQLIK ® autoinjector Injection: 360 mg/1.8 mL (200 mg/mL) in a single-dose prefilled LEQEMBI IQLIK ® autoinjector Intravenous Infusion Injection: 500 mg/5 mL (100 mg/mL) in a single-dose vial ( 3 ) Injection: 200 mg/2 mL (100 mg/mL) in a single-dose vial ( 3 ) Subcutaneous Injection Injection: 250 mg/1.25 mL (200 mg/mL) in a single-dose prefilled LEQEMBI IQLIK ® autoinjector ( 3 ) Injection: 360 mg/1.8 mL (200 mg/mL) in a single-dose prefilled LEQEMBI IQLIK ® autoinjector ( 3 )

4 CONTRAINDICATIONS LEQEMBI is contraindicated in patients with serious hypersensitivity to lecanemab-irmb or to any of the excipients. Reactions have included angioedema and anaphylaxis [see Warnings and Precautions ( 5.2 )] . LEQEMBI is contraindicated in patients with serious hypersensitivity to lecanemab-irmb or to any of the excipients. ( 4 )

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: Amyloid Related Imaging Abnormalities [see Warnings and Precautions ( 5.1 )] Hypersensitivity Reactions [see Warnings and Precautions ( 5.2 )] Infusion-Related Reactions [see Warnings and Precautions ( 5.3 )] Most common adverse reactions (at approximately 10% and higher incidence compared to placebo): infusion-related reactions, amyloid related imaging abnormality-microhemorrhages, amyloid related imaging abnormality-edema/effusion, and headache. Additionally, injection-related reactions occurred in patients receiving subcutaneously administered LEQEMBI. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Eisai Inc. at 1-888-274-2378 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. Clinical Trials with Intravenous Administration The safety of LEQEMBI has been evaluated in 2090 patients who received at least one dose of LEQEMBI by intravenous infusion. In Studies 1 and 2 in patients with Alzheimer’s disease, 1059 patients received LEQEMBI 10 mg/kg every two weeks by intravenous infusion [see Clinical Studies ( 14 )] . Of these 1059 patients, 50% were female, 79% were White, 15% were Asian, 12% were of Hispanic or Latino ethnicity, and 2% were Black. The mean age at study entry was 72 years (range from 50 to 90 years). In the combined double-blind, placebo-controlled period and long-term extension period of Studies 1 and 2, 1604 patients received LEQEMBI for at least 6 months, 1261 patients for at least 12 months, and 965 patients for 18 months. In the double-blind, placebo-controlled period in Study 1, patients stopped study treatment because of an adverse reaction in 15% of patients treated with LEQEMBI, compared to 6% patients on placebo; in Study 2, patients stopped study treatment because of an adverse reaction in 7% of patients treated with LEQEMBI, compared to 3% patients on placebo. In Study 1, the most common adverse reaction leading to discontinuation of LEQEMBI was infusion-related reactions that led to discontinuation in 2% (4/161) of patients treated with LEQEMBI, compared to 1% (2/245) of patients on placebo. In Study 2, the most common adverse reaction leading to discontinuation of LEQEMBI was ARIA-H microhemorrhages that led to discontinuation in 2% (15/898) of patients treated with LEQEMBI, compared to <1% (1/897) of patients on placebo. Table 6 shows adverse reactions that were reported in at least 5% of patients treated with LEQEMBI and at least 2% more frequently than in patients on placebo in Study 1. Table 6: Adverse Reactions Reported in at Least 5% of Patients Treated with LEQEMBI 10 mg/kg Every Two Weeks and at least 2% Higher than Placebo in Study 1 Adverse Reaction LEQEMBI 10 mg/kg Every Two Weeks N= 161 % Placebo N= 245 % Infusion-related reactions 20 3 Headache 14 10 ARIA-E 10 1 Cough 9 5 Diarrhea 8 5 Table 7 shows adverse reactions that were reported in at least 5% of patients treated with LEQEMBI and at least 2% more frequently than in patients on placebo in Study 2. Table 7: Adverse Reactions Reported in at Least 5% of Patients Treated with LEQEMBI 10 mg/kg Every Two Weeks and at least 2% Higher than Placebo in Study 2 Adverse Reaction LEQEMBI 10 mg/kg Every Two Weeks N= 898 % Placebo N= 897 % Infusion-related reactions 26 7 ARIA-H 14 8 ARIA-E 13 2 Headache 11 8 Superficial siderosis of central nervous system 6 3 Rash 1 6 4 Nausea/Vomiting 6 4 1 Rash includes acne, erythema, infusion site rash, injection site rash, rash, rash erythematous, rash pruritic, skin reactions, and urticaria. Less Common Adverse Reactions Atrial fibrillation occurred in 3% of patients treated with LEQEMBI, compare …

8 USE IN SPECIFIC POPULATIONS 8.1 Pregnancy Risk Summary There are no adequate data on LEQEMBI use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. No animal studies have been conducted to assess the potential reproductive or developmental toxicity of LEQEMBI. In the US 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. The background risk of major birth defects and miscarriage for the indicated population is unknown. 8.2 Lactation Risk Summary There are no data on the presence of lecanemab-irmb in human milk, the effects on the breastfed infant, or the effects of the drug on milk production. Published data from other monoclonal antibodies generally indicate low passage of monoclonal antibodies into human milk and limited systemic exposure in the breastfed infant. The effects of this limited exposure are unknown. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for LEQEMBI and any potential adverse effects on the breastfed infant from LEQEMBI or from the underlying maternal condition. 8.4 Pediatric Use Safety and effectiveness of LEQEMBI in pediatric patients have not been established. 8.5 Geriatric Use In Studies 1 and 2, the age of patients exposed to LEQEMBI 10 mg/kg every two weeks (n=1059) ranged from 50 to 90 years, with a mean age of 72 years; 81% were 65 years and older, and 39% were 75 years and older. No overall differences in safety or effectiveness of LEQEMBI have been observed between patients 65 years of age and older and younger adult patients.

12.1 Mechanism of Action Lecanemab-irmb is a humanized immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble and insoluble forms of amyloid beta. The accumulation of amyloid beta plaques in the brain is a defining pathophysiological feature of Alzheimer’s disease. LEQEMBI reduces amyloid beta plaques, as evaluated in Study 1 and Study 2 [see Clinical Studies ( 14 )] .

11 DESCRIPTION Lecanemab-irmb is a recombinant humanized immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble and insoluble forms of amyloid beta, and is expressed in a Chinese hamster ovary cell line. Lecanemab-irmb has an approximate molecular weight of 150 kDa. LEQEMBI Injection for Intravenous Use LEQEMBI (lecanemab-irmb) injection is a sterile, preservative-free, clear to very opalescent and colorless to pale yellow solution for intravenous infusion after dilution. LEQEMBI contains lecanemab-irmb at a concentration of 100 mg/mL in either a 500 mg/5 mL or 200 mg/2 mL single-dose vial. Each mL of solution contains 100 mg of lecanemab-irmb and arginine hydrochloride (42.13 mg), histidine (0.18 mg), histidine hydrochloride monohydrate (4.99 mg), polysorbate 80 (0.50 mg), and Water for Injection at an approximate pH of 5.0. LEQEMBI IQLIK Injection for Subcutaneous Use LEQEMBI IQLIK (lecanemab-irmb) injection is a sterile, preservative-free, clear to very opalescent, colorless to pale yellow solution for subcutaneous use. LEQEMBI IQLIK contains lecanemab-irmb at a concentration of 200 mg/mL in either a 360 mg/1.8 mL or 250 mg/1.25 mL single-dose prefilled autoinjector with a 29-gauge fixed 1⁄2-inch needle. Each 360 mg/1.8 mL LEQEMBI IQLIK autoinjector contains 360 mg of lecanemab-irmb formulated in: arginine hydrochloride (75.83 mg), histidine (0.25 mg), histidine hydrochloride monohydrate (9.09 mg), polysorbate 80 (0.90 mg), and Water for Injection, USP. Each 250 mg/1.25 mL LEQEMBI IQLIK autoinjector contains 250 mg of lecanemab-irmb formulated in: arginine hydrochloride (52.66 mg), histidine (0.18 mg), histidine hydrochloride monohydrate (6.31 mg), polysorbate 80 (0.63 mg), and Water for Injection, USP.

16 HOW SUPPLIED/STORAGE AND HANDLING 16.1 How Supplied LEQEMBI single-dose vials and LEQEMBI IQLIK single-dose prefilled autoinjectors contain lecanemab-irmb as a sterile, preservative-free, clear to very opalescent, and colorless to pale yellow solution, available as described below. Intravenous Infusion Each LEQEMBI glass vial is closed with a stopper and flip cap and is available as follows: Strength Pack Size NDC Injection: 500 mg/5 mL (100 mg/mL) Carton of 1 single-dose vial 62856-215-01 Injection: 200 mg/2 mL (100 mg/mL) Carton of 1 single-dose vial 62856-212-01 Subcutaneous Injection Each LEQEMBI IQLIK prefilled autoinjector consists of a 2.25 mL syringe with a fixed 29-gauge 1⁄2-inch needle with needle guard and is available as follows: Strength Pack Size NDC Injection: 250 mg/1.25 mL (200 mg/mL) Carton of 2 single-dose prefilled autoinjectors 62856-222-02 Injection: 360 mg/1.8 mL (200 mg/mL) Carton of 1 single-dose prefilled autoinjector 62856-220-01 LEQEMBI IQLIK is not made with natural rubber latex. 16.2 Storage and Handling Intravenous Infusion Unopened Vial Store LEQEMBI vials in a refrigerator at 2°C to 8°C (36°F to 46°F). Store in the original carton to protect from light. Do not freeze or shake. Diluted Solution For storage of the diluted infusion solution, see Dosage and Administration ( 2.5 ) . Subcutaneous Injection Store LEQEMBI IQLIK autoinjectors in a refrigerator at 2°C to 8°C (36°F to 46°F). Store in original carton to protect from light. Do not freeze. If needed, the autoinjectors can be stored at room temperature up to 25°C (77°F) in the original carton for up to 14 days. Once the autoinjector has been stored at room temperature, do not return it to the refrigerator. Discard the autoinjector(s) if these conditions are exceeded.

16.1 How Supplied LEQEMBI single-dose vials and LEQEMBI IQLIK single-dose prefilled autoinjectors contain lecanemab-irmb as a sterile, preservative-free, clear to very opalescent, and colorless to pale yellow solution, available as described below. Intravenous Infusion Each LEQEMBI glass vial is closed with a stopper and flip cap and is available as follows: Strength Pack Size NDC Injection: 500 mg/5 mL (100 mg/mL) Carton of 1 single-dose vial 62856-215-01 Injection: 200 mg/2 mL (100 mg/mL) Carton of 1 single-dose vial 62856-212-01 Subcutaneous Injection Each LEQEMBI IQLIK prefilled autoinjector consists of a 2.25 mL syringe with a fixed 29-gauge 1⁄2-inch needle with needle guard and is available as follows: Strength Pack Size NDC Injection: 250 mg/1.25 mL (200 mg/mL) Carton of 2 single-dose prefilled autoinjectors 62856-222-02 Injection: 360 mg/1.8 mL (200 mg/mL) Carton of 1 single-dose prefilled autoinjector 62856-220-01 LEQEMBI IQLIK is not made with natural rubber latex.