Lecanemab-irmb is an anti-amyloid monoclonal antibody developed by Eisai and Biogen and marketed internationally as LEQEMBI. In China, it is approved for early Alzheimer’s disease, covering mild cognitive impairment due to Alzheimer’s disease and mild Alzheimer’s dementia in the population described by the local label.
This explainer expands the client-supplied medicine brief with current official prescribing information. It is intended to clarify the treatment pathway and the main differences between lecanemab and donanemab; it is not a substitute for an individual neurological assessment.
How lecanemab works
Lecanemab is an immunoglobulin G1 antibody directed against aggregated soluble and insoluble forms of amyloid beta. It binds soluble protofibrils as well as amyloid deposits, helping reduce amyloid pathology in the brain.
Who may be considered for treatment
Treatment is initiated in the early symptomatic stages studied in clinical trials: mild cognitive impairment or mild dementia due to Alzheimer’s disease. Amyloid pathology must be confirmed before treatment. The benefit-risk assessment is individual and should consider neurological status, MRI findings, medicines that affect bleeding risk and the patient’s ability to complete repeated infusions and monitoring.
Administration and safety monitoring
Initial treatment
The China and U.S. intravenous schedules start with 10 mg/kg once every two weeks. Maintenance options and approved formulations differ by market, so the current local label must always be checked.
Before treatment
Confirm amyloid pathology, obtain a recent baseline brain MRI and discuss apolipoprotein E ε4 testing because homozygous carriers have a higher incidence of symptomatic and severe amyloid-related imaging abnormalities.
During treatment
Serial MRI examinations and symptom review are required. Headache, confusion, visual changes, dizziness, nausea, gait difficulty, focal neurological deficits or seizures require prompt clinical assessment.
Lecanemab and donanemab: key differences
Developer
Lecanemab is developed by Eisai and Biogen. Donanemab, marketed as KISUNLA in the United States, is developed by Eli Lilly.
Amyloid target
Lecanemab binds aggregated soluble and insoluble amyloid beta, including protofibrils. Donanemab targets insoluble N-truncated pyroglutamate amyloid beta found in deposited plaque.
Starting population
Both are used in early symptomatic Alzheimer’s disease—the mild cognitive impairment or mild dementia stage—with confirmed amyloid pathology, according to the applicable approved label.
Infusion pattern
Intravenous lecanemab begins every two weeks. Donanemab is given every four weeks with stepwise dose escalation under the current U.S. label.
Treatment course
The current U.S. donanemab label allows clinicians to consider stopping after amyloid plaques are reduced to a minimal level on amyloid PET. Lecanemab follows its own continuing treatment and maintenance framework. Local approvals and labels may differ.
Important shared risks
Both treatments can cause amyloid-related imaging abnormalities, including brain swelling and small or larger areas of bleeding. Infusion-related reactions can also occur. These risks make specialist selection, MRI surveillance, apolipoprotein E ε4 risk discussion and careful review of anticoagulant or thrombolytic exposure essential.
Neither medicine reverses all established neurological damage, and they are not interchangeable products. The appropriate option—if either is suitable—depends on the approved local label, patient characteristics, treatment access and a specialist’s benefit-risk assessment.