The European Commission has officially granted marketing authorization for Leqembi (lecanemab), marking a historic milestone in neurological care . This Leqembi EU approval introduces the first disease-modifying therapy in the region that targets an underlying cause of early Alzheimer’s disease to slow its progression . The decision applies to all 27 European Union member states, as well as Iceland, Liechtenstein, and Norway . By addressing the root mechanisms of cognitive decline, this breakthrough offers renewed hope for patients facing a devastating condition .
Developed collaboratively by Eisai and Biogen, the therapy represents a major shift in addressing memory loss and cognitive impairment . The Leqembi EU approval specifically authorizes the medication for adult patients diagnosed with mild cognitive impairment or mild dementia caused by Alzheimer’s disease . Eisai will serve as the marketing authorization holder across the region and will co-promote the medication alongside Biogen . In the Nordic countries, Eisai will partner with BioArctic, the company that originally developed the drug .
How Leqembi Targets Alzheimer’s Disease
Alzheimer’s disease is characterized by the toxic accumulation of a protein known as amyloid-beta in the brain . Over time, this protein clumps together to form soluble protofibrils and insoluble plaques, which drive neurodegeneration . Leqembi is an amyloid-beta monoclonal antibody designed to bind to these toxic formations and promote their clearance by the immune system . By preferentially targeting the highly neurotoxic protofibrils and the insoluble plaques, the treatment actively slows down the worsening of cognitive and functional symptoms .
Strict Eligibility and Patient Testing
The European Commission has established strict clinical conditions for the drug’s use . The treatment is exclusively indicated for patients who have confirmed amyloid pathology in the brain and who carry one or zero copies of the APOE4 (Apolipoprotein E ε4) gene variant . The APOE4 gene is recognized as the strongest genetic risk factor for Alzheimer’s . Patients with two copies of this gene variant face a significantly higher risk of experiencing severe side effects, which is why they are excluded from the current EU indication .
Administration and Clinical Evidence
Eligible patients will receive Leqembi through intravenous infusions . The standard dosing regimen is set at 10 milligrams per kilogram of body weight, administered once every two weeks . Regulators based this approval on comprehensive data gathered from the global Phase 3 Clarity AD clinical trial . This 18-month, placebo-controlled, double-blind study involved 1,795 patients with early Alzheimer’s disease . The trial successfully met its primary endpoint on the clinical dementia rating scale, demonstrating that the medication significantly slowed cognitive decline compared to a placebo .
Managing Potential Side Effects
Despite its proven benefits, the medication carries risks . The most common adverse reactions observed during the trial included infusion-related reactions, headaches, and a specific class of side effects known as amyloid-related imaging abnormalities (ARIA) . ARIA can manifest as brain swelling or microscopic brain bleeding . Because of these risks, regulators concluded that the benefits of the drug outweigh the dangers only when strictly applied to the indicated patient population and accompanied by robust risk minimization measures .
A Complex Regulatory Journey
The path to this authorization was not straightforward . The decision comes after a reaffirmed positive scientific assessment by the European Medicines Agency’s (EMA) committee . However, both the Standing Committee on Medicinal Products for Human Use and the European Commission’s Appeal Board were unable to reach a verdict, returning a “no opinion” result . Ultimately, the matter was referred directly to the European Commission, which finalized the authorization on April 15, 2025, setting clear risk mitigation requirements for healthcare providers .
Global Impact and Future Access
This European authorization marks the thirteenth global approval for Leqembi, which is already available in countries such as the U.S., Japan, China, Israel, and the U.K. . Biogen CEO Christopher A. Viehbacher described the approval as a landmark advancement in a field that has seen little innovation over the past 20 years . Meanwhile, Eisai CEO Haruo Naito emphasized the company’s commitment to making the drug accessible, stating they are working collaboratively with national reimbursement authorities across the EU .
Because national payers will now assess the treatment against their own criteria, the speed of rollout will vary by country . George Vradenburg, chair of UsAgainstAlzheimer’s, celebrated the news as a victory for patients, adding that it offers crucial hope and proves that global momentum is building to finally end Alzheimer’s disease .
