Lecanemab
Anti-amyloid monoclonal antibodies
Anti-amyloid monoclonal antibodies
Monoclonal antibody against amyloid beta for early Alzheimer disease. It slows decline; its main risk is brain swelling and bleeding (ARIA).
Also called: Lecanemab-irmb
Quick facts
- Group
- Anti-amyloid monoclonal antibodies
- Target
- Aggregated amyloid beta (Aβ), cleaved from amyloid precursor protein
- Key effects
- Headache · Infusion-related reactions
- Monitor
- ApoE ε4 genotype before starting · MRI before starting
- ATC
- N06DX04
No doses: the clinician sets them by the current guideline.
Mechanism of action
Lecanemab is a monoclonal antibody directed against amyloid beta. It binds aggregated Aβ in the brain and lowers the amount of amyloid plaque, a defining feature of Alzheimer disease. In the confirmatory trial, starting it at the mild cognitive impairment or mild dementia stage slowed clinical decline compared with placebo. It treats the disease but does not cure it.
- The antibody reaches the brain and binds aggregated amyloid beta
- Amyloid plaque burden falls
- Clinical decline is slowed, without reversing damage already done
- Amyloid in vessel walls can react: oedema or microbleeds (ARIA)
Indications
- Alzheimer disease at the mild cognitive impairment or mild dementia stage, with confirmed amyloid beta pathology Alzheimer disease →
Adverse effects
Common
- Headache
- Infusion-related reactions (fever, chills, nausea, dizziness, fast heartbeat, breathlessness)
- Injection-site redness, swelling, pain or bruising
- Cough and diarrhoea
Contraindications
- Serious hypersensitivity to lecanemab or to any of its inactive ingredients
Key interactions
- Anticoagulants
- More intracerebral haemorrhages than with placebo; caution is advised.
- Aspirin and other drugs that may cause bleeding
- Listed as interacting; their use is reviewed with the treating team before and during treatment.
What is monitored
- ApoE ε4 genotype before starting (homozygotes have more, and more serious, ARIA)
- MRI before starting and at intervals during treatment
- New headache, confusion, visual change, gait disturbance or seizures (possible ARIA)
- Signs of infusion reaction during and shortly after the infusion
Administration and safety
- Intravenous infusions are given by a doctor or nurse in a health-care setting, with observation during and after the infusion.
- Inspect the solution: it should be clear to pale yellow; it is not used if cloudy, discoloured or with particles, and it is not shaken.
- The subcutaneous autoinjector is warmed to room temperature on its own, never with heat; the first injections are given in the office before home use.
- The patient carries identification stating that they receive lecanemab.
Pregnancy and breastfeeding
It is used in older adults with Alzheimer disease; pregnancy or breastfeeding is reported to the treating doctor before and during treatment.
Nursing care
- Before each infusion, check that the planned MRI was done and ask about anticoagulants, antiplatelets and new neurological symptoms.
- During and after the infusion, watch for fever, chills, dizziness, tachycardia and breathlessness.
- Teach patient and carers the warning signs of ARIA and to seek urgent care if they appear.
- Report hives, swelling of lips, tongue or throat, or difficulty breathing at once.
Pharmacokinetics
- Absorption
- Given by intravenous infusion in a health-care setting, or by subcutaneous injection with a prefilled autoinjector.
Test yourself
Think of the answer, then tap the question to see it.
What does lecanemab bind, and what is the result?
Aggregated amyloid beta in the brain; plaque burden falls and clinical decline is slowed, without a cure.
Which patients are at higher risk of ARIA with lecanemab?
ApoE ε4 homozygotes; ApoE status is tested before starting.
Why is caution needed in patients on anticoagulants?
Anticoagulants were associated with more intracerebral haemorrhages in patients taking lecanemab.
Which imaging test is done before and during treatment?
Brain MRI, to detect ARIA (oedema or microhaemorrhages).
Connections
← Back to the class: Anti-amyloid monoclonal antibodies
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Lecanemab-irmb Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); FDA Converts Novel Alzheimer’s Disease Treatment to Traditional Approval (U.S. Food and Drug Administration, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.