Last reviewed 2026-05-27 · How we verify

LEQEMBI (LECANEMAB-IRMB)

LEQEMBI (generic name: LECANEMAB-IRMB) is a Amyloid Beta-directed Antibody [EPC] drug developed by EISAI INC. It is currently FDA-approved for Alzheimer's disease.

LEQEMBI is an antibody that targets the amyloid-beta A4 protein, classified as an inhibitor. It is being studied for the treatment of Alzheimer's Disease and Mild Cognitive Impairment due to Alzheimer's Disease.

At a glance

Approved indications

• Alzheimer's disease

Boxed warnings

• WARNING: 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) and ARIA with hemosiderin deposition (ARIA-H). Incidence and timing of ARIA vary among treatments. ARIA usually occurs early in treatment and is usually asymptomatic, although serious and life-threatening events can occur. ARIA can be fatal. Serious intracerebral hemorrhage s > 1 cm, some of which have been fatal, have been observed in patients treated with this class of medications. Because ARIA-E can cause focal neurologic deficits that can mimic an ischemic stroke, treating clinicians should consider whether such symptoms could be due to ARIA-E before giving thrombolytic therapy to a patient being treated with LEQEMBI [see Warnings and Precautions ( 5.1 ), Adverse Reactions ( 6.1 )]. ApoE ε4 Homozygotes Patients who are apolipoprotein E ε4 (ApoE ε4) homozygotes (approximately 15% of Alzheimer’s disease patients) treated with this class of medications, including LEQEMBI, have a higher incidence of ARIA, including symptomatic, serious, and severe radiographic ARIA, compared to heterozygotes and noncarriers. Testing for ApoE ε4 status should be performed prior to initiation of treatment to inform the risk of developing ARIA. Prior to testing, prescribers should discuss with patients the risk of ARIA across genotypes and the implications of genetic testing results. Prescribers should inform patients that if genotype testing is not performed they can still be treated with LEQEMBI; however, it cannot be determined if they are ApoE ε4 homozygotes and at higher risk for ARIA [see Warnings and Precautions ( 5.1 )]. Consider the benefit of LEQEMBI for the treatment of Alzheimer’s disease and potential risk of serious adverse events associated with ARIA when deciding to initiate treatment with LEQEMBI [see Warnings and Precautions ( 5.1 ) and Clinical Studies ( 14 )]. WARNING: AMYLOID RELATED IMAGING ABNORMALITIES See full prescribing information for complete boxed warning. Monoclonal antibodies directed against aggregated forms of beta amyloid, including LEQEMBI, can cause amyloid related imaging abnormalities (ARIA), as ARIA with edema (ARIA-E) and ARIA with hemosiderin deposition (ARIA-H). ARIA is usually asymptomatic, although serious and life-threatening events can occur. ARIA can be fatal. Serious intracerebral hemorrhages > 1 cm have occurred in patients treated with this class of medications. ARIA-E can cause focal neurologic deficits that can mimic ischemic stroke. ( 5.1 , 6.1 ) ApoE ε4 Homozygotes Patients treated with this class of medications, including LEQEMBI, who are ApoE ε4 homozygotes have a higher incidence of ARIA, including symptomatic and serious ARIA, compared to heterozygotes and noncarriers. Testing for ApoE ε4 status should be performed prior to initiation of treatment to inform the risk of developing ARIA. Prior to testing, the risk of ARIA across genotypes and implications of genetic testing results should be discussed with patients. ( 5.1 ) Consider the benefit for the treatment of Alzheimer’s disease and risk of ARIA when deciding to treat with LEQEMBI. ( 5.1 , 14 )

Common side effects

• Infusion-related reactions
• Amyloid related imaging abnormality-microhemorrhages
• Amyloid related imaging abnormality-edema/effusion
• Headache
• Atrial fibrillation
• Lymphopenia/decreased lymphocyte count
• Localized injection-related reactions (erythema, induration, swelling, heat, pain, pruritis, rash, ecchymosis, hematoma)
• Systemic injection-related reactions

Serious adverse events

• Infusion-related reactions (leading to discontinuation)
• ARIA-H microhemorrhages (leading to discontinuation)

Key clinical trials

• Assessment of Safety and Feasibility of Exablate Blood-Brain Barrier Disruption for the Treatment of Patients With With Mild Cognitive Impairment (MCI) or Mild Alzheimer's Disease (AD) Undergoing Stan (EARLY/Phase 1)
• A Phase 2, Placebo-Controlled, Double-Blind, Parallel-Group, Dose-Finding Study to Evaluate Safety, Tolerability, and Biomarker Efficacy of E2814 With Concurrent Lecanemab Treatment in Subjects With E (Phase 2)
• A 12-month Single-arm Real-world Study to Determine the Safety and Efficacy of Lecanemab in Patients With Early Alzheimer's Disease (Phase 4)
• Georgia Memory Net Center for Medicare and Medicaid Services Registry for Anti-Amyloid Monoclonal Antibody Coverage With Evidence Development (N/A)
• Proof of Concept of the Effect of LEQEMBI on Cerebral and Retinal Amyloid in Mild Cognitive Impairment Due to Alzheimer's Disease (N/A)

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• LEQEMBI CI brief — competitive landscape report
• LEQEMBI updates RSS · CI watch RSS
• EISAI INC portfolio CI

Frequently asked questions about LEQEMBI

Related

• Drug class: All Amyloid Beta-directed Antibody [EPC] drugs
• Target: All drugs targeting Amyloid beta A4 protein
• Manufacturer: EISAI INC — full pipeline
• Therapeutic area: All drugs in Neuroscience
• Indication: Drugs for Alzheimer's disease

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing