Lecanemab

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

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 within approximately one week prior to the 3 rd , 5 th , 7 th , and 14 th infusions. If radiographically observed ARIA occurs, treatment recommendations are based on type, severity, and presence of symptoms. ( 2.4 , 5.1 ) Recommended starting dosage: 10 mg/kg once every 2 weeks administered after dilution as an intravenous infusion over approximately one hour. ( 2.2 ) After 18 months, continue treatment once every 2 weeks 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 as an intravenous infusion using the starting dosage (see Table 1). After 18 months, the starting dosage may be continued or a transition to maintenance dosage regimen may be considered, which can be administered by either intravenous infusion or subcutaneous injection (see Table 1). If transitioning from starting dosage to a maintenance dosage regimen, administer the first maintenance dose two weeks after the last starting dose.

Amyloid Related Imaging Abnormalities (ARIA): Enhanced clinical vigilance for ARIA is recommended during the first 14 weeks of treatment with LEQEMBI. Risk of ARIA, including symptomatic ARIA, was increased in apolipoprotein E ε4 homozygotes compared to heterozygotes and noncarriers. The risk of ARIA-E and ARIA-H is increased in patients with pretreatment microhemorrhages and/or superficial siderosis. If a patient experiences symptoms suggestive of ARIA, clinical evaluation should be performed, including MRI scanning if indicated. ( 2.4 , 5.1 ) Infusion-Related Reactions: The infusion rate may be reduced, or the infusion may be discontinued, and appropriate therapy administered as clinically indicated. Consider pre-medication at subsequent dosing with antihistamines, non-steroidal anti-inflammatory drugs, or corticosteroids. ( 5.3 ) 5.1 Amyloid Related Imaging Abnormalities Monoclonal antibodies directed against aggregated forms of beta amyloid, including LEQEMBI, can cause amyloid related imaging abnormalities (ARIA), characterized as ARIA with edema (ARIA-E), which can be observed on MRI as brain edema or sulcal effusions, and ARIA with hemosiderin deposition (ARIA-H), which includes microhemorrhage and superficial siderosis. ARIA can occur spontaneously in patients with Alzheimer’s disease, particularly in patients with MRI findings suggestive of cerebral amyloid angiopathy, such as pretreatment microhemorrhage or superficial siderosis.

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. ( 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).

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.

Metabolism

Steady-state concentrations of lecanemab-irmb were reached after 6 weeks of 10 mg/kg administered every 2 weeks and systemic accumulation was 1.4-fold. The peak concentration (C max ) and area under the plasma concentration versus time curve (AUC) of lecanemab-irmb increased dose proportionally in the dose range of 0.3 to 15 mg/kg following single dose.

• Jan 6, 2023BLABLA761269Eisai Inc
• Aug 29, 2025BLABLA761375Eisai Inc

1. 1Headache46314%
2. 2Amyloid Related Imaging Abnormality-oedema/effusion44913%
3. 3Amyloid Related Imaging Abnormality-microhaemorrhages And Haemosiderin Deposits41412%
4. 4Infusion Related Reaction2838.5%
5. 5Chills2397.2%
6. 6Fatigue2136.4%
7. 7Pyrexia1715.1%
8. 8Dizziness1634.9%
9. 9Confusional State1624.8%
10. 10Nausea1424.3%
11. 11Cerebral Haemorrhage1063.2%
12. 12Fall993.0%
13. 13Amyloid Related Imaging Abnormalities942.8%
14. 14Vomiting872.6%
15. 15Tremor862.6%

The 10 most recently updated of 32 ClinicalTrials.gov registrations naming Lecanemab as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• InRAD Observational Study
  Recruiting · Observational · 50,000 enrolled · Stichting International Registry for Alzheimer's Disease and other Dementias Foundation
  NCT07213700updated 2026-06-08
• AHEAD 3-45 Study: A Study to Evaluate Efficacy and Safety of Treatment With Lecanemab in Participants With Preclinical Alzheimer's Disease and Elevated Amyloid and Also in Participants With Early Preclinical Alzheimer's Disease and Intermediate Amyloid
  Active not recruiting · Phase 3 · Interventional · 1,400 enrolled · Eisai Inc.
  NCT04468659updated 2026-06-04
• Evaluating the Efficacy and Safety of Lecanemab in Alzheimer's Disease Through Multi-omics Approachs
  Recruiting · Phase 4 · Interventional · 200 enrolled · First Affiliated Hospital of Wenzhou Medical University
  NCT07604896updated 2026-05-22
• Amyloid Monoclonal Antibody Treatment in PD Patients With Coexistent AD Pathology
  Not yet recruiting · Interventional · 60 enrolled · Yonsei University
  NCT07544953updated 2026-04-22
• Cognitive Neurology Unit Clinical Registry
  Recruiting · Observational · 500 enrolled · Beth Israel Deaconess Medical Center
  NCT05925621updated 2026-04-13
• A Study to Confirm Safety and Efficacy of Lecanemab in Participants With Early Alzheimer's Disease
  Active not recruiting · Phase 3 · Interventional · 1,906 enrolled · Eisai Inc.
  NCT03887455updated 2026-04-07
• Efficacy of Lecanemab at Different Therapeutic Doses for Alzheimer's Disease (AD) in Real-World Practice
  Not yet recruiting · Observational · 140 enrolled · Second Affiliated Hospital, School of Medicine, Zhejiang University
  NCT07505095updated 2026-04-01
• Georgia Memory Net Anti-Amyloid Monoclonal Antibody Registry
  Recruiting · Observational · 735 enrolled · Emory University
  NCT05999084updated 2026-03-11
• Making Antibody Treatments More Effective in Early Alzheimer's Disease Using 3Tesla Magnetica Resonance
  Not yet recruiting · Interventional · 50 enrolled · IRCCS San Raffaele
  NCT07456462updated 2026-03-06
• DIAN-TU Amyloid Removal Trial (ART) in Dominantly Inherited Alzheimer's Disease
  Active not recruiting · Phase 3 · Interventional · 40 enrolled · Washington University School of Medicine
  NCT06384573updated 2026-03-05

Frequently asked questions

How does Lecanemab work?

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.

What is Lecanemab used for?

According to FDA labeling, Lecanemab carries indications including: 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.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Lecanemab?

Lecanemab is classified as Other anti-dementia drugs, Amyloid Beta-directed Antibody, Amyloid Beta-directed Antibody Interactions.

What are the brand names for Lecanemab?

Lecanemab is marketed under brand names including Leqembi.

What are the contraindications for Lecanemab?

Lecanemab labeling lists contraindications including: LEQEMBI is contraindicated in patients with serious hypersensitivity to lecanemab-irmb or to any of the excipients of LEQEMBI or LEQEMBI IQLIK. Reactions have included angioedema and anaphylaxis [see Warnings and Precautions ( 5.2 )].. Always consult the full prescribing information and a clinician.