| Monoclonal antibody | |
|---|---|
| Type | Whole antibody |
| Source | Humanized |
| Target | Amyloid beta |
| Clinical data | |
| Trade names | Leqembi |
| Other names | BAN2401, lecanemab-irmb |
| AHFS/Drugs.com | Monograph |
| License data | |
| Routes of administration | Intravenous,subcutaneous |
| ATC code | |
| Legal status | |
| Legal status | |
| Identifiers | |
| CAS Number | |
| DrugBank | |
| ChemSpider |
|
| UNII | |
| KEGG | |
| Chemical and physical data | |
| Formula | C6544H10088N1744O2032S46 |
| Molar mass | 147181.62 g·mol−1 |
Lecanemab, sold under the brand nameLeqembi, is amonoclonal antibody medication used for the treatment ofAlzheimer's disease.[2][6] Lecanemab is anamyloid beta-directed antibody.[2] It is given viaintravenous infusion orsubcutaneous injection to people withmild cognitive impairment or mild dementia.[2] In clinical trials, it demonstrated modest efficacy in reducing relative cognitive decline compared to placebo.[7] The most common side effects of lecanemab include headache, infusion-related reactions, andamyloid-related imaging abnormalities, a side effect known to occur with the class of antibodies targeting amyloid.[8]
Lecanemab was jointly developed byEisai,Biogen, andBioArctic.[9] It was grantedaccelerated approval for medical use in the United States in January 2023,[10] and fully approved by the FDA in July 2023.[6][11]
Lecanemab was approved for medical use in South Korea in May 2024,[12] and in Mexico in December 2024.[13] In Canada, it was approved in October 2025, but was not covered by provincial insurance programs.[14]
Lecanemab isindicated for the treatment of Alzheimer's disease in people who have mild cognitive impairment or mild dementia, but not in people who already have moderate or severe dementia.[2][6][8]
In aphase III clinical trial of 1,795 participants aged 50 to 90 years old with early-stage Alzheimer's disease, lecanemab slowed clinical decline by 27% after 18 months of treatment compared with those who received a placebo.[15][16] The meanCDR-SOB score at baseline was approximately 3.2 among the study population, and the mean change from baseline after 18 months was +1.21 with lecanemab and +1.66 with placebo. (For the comparison, CDR-SOB score is 0 for theNormal level, 0.5–2.5 for Questionable impairment, 3.0–4.0 forVery mild dementia, 4.5–9.0 for Mild dementia, 9.5–15.5 for Moderate dementia, and 16.0–18.0for Severe dementia.)[17] The authors concluded "Lecanemab reduced markers of amyloid in early Alzheimer's disease and resulted in moderately less decline on measures of cognition and function than placebo at 18 months but was associated with adverse events."[16]
Lecanemab may causeamyloid-related imaging abnormalities (ARIA). ARIA is oftenasymptomatic, but serious and life-threatening events rarely may occur. ARIA most commonly presents as temporary swelling of the brain that usually resolves over time and may be accompanied by small spots of bleeding in or on the surface of the brain, though some people may have symptoms such as headache, confusion, dizziness, vision changes, nausea and seizure.[6][8] Compared to placebo, all doses of the drug caused accelerated brain shrinkage.[18]
Lecanemab is amonoclonal antibody consisting of thehumanized version[19] of a mouse antibody, mAb158, that recognizesprotofibrils and preventsamyloid beta deposition inanimal models of Alzheimer's disease.[20]
In July 2022, the USFood and Drug Administration (FDA) accepted an application foraccelerated approval for lecanemab.[21]
In September 2022,Biogen announced[21][22] positive results from an ongoingphase III clinical trial.[23][24]
In November 2022, it was announced that the drug was a success in clinical trials, and exceeded its goal in reaching primary endpoints.[25]
The efficacy of lecanemab was evaluated in a double-blind, placebo-controlled, parallel-group, dose-finding study of 856 participants with Alzheimer's disease.[6] Treatment was initiated in participants whose disease was in the stage of mildcognitive impairment or milddementia and who had confirmed presence of amyloid beta pathology.[6] Participants receiving the treatment showed significant dose- and time-dependent reduction of amyloid beta plaque: Those receiving the approved dose of lecanemab, 10 milligrams/kilogram every two weeks, had a statistically significant reduction in brain amyloid plaque from baseline to week 79 compared with those receiving a placebo, who had no reduction of amyloid beta plaque.[6]
The FDA approved lecanemab in January 2023, via theaccelerated approval pathway for the treatment of Alzheimer's disease.[6] The FDA granted the application for lecanemabfast track,priority review, andbreakthrough therapy designations.[6] The approval of Leqembi was granted toEisai R&D Management Co., Ltd.[6] In July 2023, the FDA converted lecanemab to traditional approval.[8]
Efficacy of lecanemab was evaluated using the results of Study 301 (CLARITY AD), a phase III randomized, controlled clinical trial.[8] Study 301 was a multicenter, randomized, double-blind, placebo-controlled, parallel-group study that enrolled 1,795 participants with Alzheimer's disease.[8] Treatment was initiated in participants with mild cognitive impairment or mild dementia stage of disease and confirmed presence of amyloid beta pathology.[8] Participants were randomized in a 1:1 ratio to receive placebo or lecanemab at a dose of 10 milligrams (mg)/kilograms (kg), once every two weeks.[8] Lecanemab demonstrated a reduction of decline from baseline to 18 months on the primary endpoint, theClinical Dementia Rating Scale Sum of Boxes score, compared to placebo.[8] Statistically significant differences between treatment groups were also demonstrated on all secondary endpoints, which included theAlzheimer's Disease Assessment Scale Cognitive Subscale 14, and theAlzheimer's Disease Cooperative Study–Activities of Daily Living Scale for Mild Cognitive Impairment.[8]
On 29 August 2025, the FDA approved a new subcutaneous auto-injector form called "Leqembi IQLIK". It can be given one weekly after 18 months of IV therapy every 2 weeks[26]
Lecanemab is approved in the US, Japan, China, South Korea, Hong Kong, Israel, United Arab Emirates, and Great Britain.[27]
In October 2024, the AustralianTherapeutic Goods Administration (TGA) decided not to register lecanemab.[28] In December 2024, Eisai requested reconsideration of the decision, and the TGA confirmed its decision to not register lecanemab in March 2025.[29][30]
In October 2025, lecanemab (named asLeqembi) was authorized in Canada for use by intravenous injection every two weeks during early stages of dementia when there is evidence of a person having mild cognitive impairment.[14] Due to its high cost (about US$26,000 per year), lecanemab was not included for coverage in the public health system.[14]
In July 2024, theCommittee for Medicinal Products for Human Use (CHMP) of theEuropean Medicines Agency (EMA) recommended the refusal of the marketing authorization for lecanemab. The manufacturer requested re-examination.[3]
In November 2024, after re-examining its initial opinion, the CHMP recommended granting a marketing authorization to lecanemab (Leqembi) for treating mild cognitive impairment (memory and thinking problems) or mild dementia due to Alzheimer's disease (early Alzheimer's disease) in people who have only one or no copy of ApoE4, a certain form of the gene for the protein apolipoprotein E.[3][31] Lecanemab was authorized for medical use in the European Union in April 2025.[3][4]
In August 2024, theMedicines and Healthcare products Regulatory Agency (MHRA) granted marketing authorization for England, Scotland, and Wales. It may not be used in people with two copies of theApoE4 allele. Statistically, these people develop Alzheimer's disease more frequently and earlier, but also have a particularly high incidence of ARIA when treated with lecanemab. According to the MHRA, the risk outweighs the benefit for these people and genetic testing is recommended before starting treatment.[32][33][34]
The English branch of theNational Health Service (NHS) announced it would not cover the costs of treatment, as according to draft guidance from theNational Institute for Health and Care Excellence (NICE), the small benefit does not justify the cost of treatment.[32][33][34]
Drugs in Northern Ireland are regulated by theEuropean Medicines Agency afterBrexit in accordance with theNorthern Ireland Protocol.[34]
In January 2023, the FDA granted accelerated approval for lecanemab.[6][35] In July 2023, the FDA converted lecanemab to traditional approval.[8]
In October 2023, lecanemab was designated as a Do Not Use drug byPublic Citizen's Health Research Group.[36] It had urged the FDA not to approve it, arguing that there were serious safety concerns and very small treatment benefits.[36]
Lecanemab pricing isUS$26,500 per year,[37] with a company-estimated "per-patient societal value" of $37,600.[38] However, cost-effectiveness analysis by theInstitute for Clinical and Economic Review (ICER) concluded that a broad range of $8,900 to $21,500 would be appropriate.[39] According to an estimate by the manufacturer, Eisai, about 85% of eligible people with early-Alzheimer's in the United States are covered byMedicare.[38]
After reviewing the clinical evidence and considering the treatments' other potential benefits, disadvantages, and contextual considerations noted above, the California Technology Assessment Forum unanimously concluded that lecanemab represents "low" long-term value of money.[39] At lecanemab's net price, approximately 5% of the 1.4 million people in the US eligible for Alzheimer's disease treatment that targets beta-amyloid could be treated within five years without crossing the ICER potential budget impact threshold of $777 million per year.[39] As a result, ICER issued an access and affordability alert for lecanemab in the management of Alzheimer's disease. This alert indicates that the health care costs of the treatment might stress the health system in the short term, resulting in the displacement of other services and a rapid increase in insurance costs.[39]
Lecanemab is theinternational nonproprietary name.[40]
Lecanemab was jointly developed by the companiesEisai,Biogen,BioArctic and is inclinical trials for the treatment ofAlzheimer's disease.[41]
It has shown statistically significant but minor effectiveness, with studies suggesting a modest decrease incognitive decline in Alzheimer's participants compared with acontrol group given aplacebo instead.[42]
According to a phase III clinical trial (n = 1795), lecanemab has been associated with both ARIA-E (cerebral edema) and ARIA-H (microhaemorrhages, or smallhaemorrhages, andhemosiderosis) sub-types.[16] Mild to moderate infusion-related reactions may also occur.[16]
This article incorporates text from this source, which is in thepublic domain. This article incorporates text from this source, which is in thepublic domain.
