On April 16, 2025, Biogen and its partner Eisai celebrated a significant milestone in the fight against Alzheimer’s disease (AD) as the European Commission (EC) granted marketing authorization for their drug Leqembi (lecanemab). This approval marks a pivotal moment, making Leqembi the first therapy in the European Union (EU) designed to slow the progression of early Alzheimer’s disease.
The regulatory body has specifically approved Leqembi for use in adult patients diagnosed with mild cognitive impairment or mild dementia due to Alzheimer’s, provided they are apolipoprotein E ε4 (ApoE ε4) non-carriers or heterozygotes with confirmed amyloid pathology. This decision applies to all 27 EU member states, as well as Iceland, Liechtenstein, and Norway.
Gary Hendler, regional chairman and CEO at Eisai EMEA, expressed his enthusiasm for the approval, stating, “Today’s decision makes lecanemab the first treatment option in the European Union that can slow the progression of early Alzheimer’s disease and is a key step to making the medicine available to eligible patients.”
The journey to this approval was not without its challenges. The European Medicines Agency’s (EMA) Committee for Medicinal Products for Human Use (CHMP) initially issued a negative opinion regarding Leqembi’s marketing approval in July 2024. Their concerns centered around the drug's safety profile, particularly the risk of amyloid-related imaging abnormalities (ARIA), which can lead to brain swelling and bleeding.
Despite the initial setback, Eisai appealed the decision, and in November 2024, the CHMP reversed its stance, recommending marketing approval for the drug. This recommendation was based on phase 3 data from the Clarity AD trial, which demonstrated that Leqembi slowed disease progression compared to placebo over an 18-month period. Specifically, treatment with Leqembi reduced clinical decline on the global cognitive and functional scale, CDR-SB, by 31% compared to placebo.
However, the approval came with strict conditions. The EC stipulated that Leqembi could only be administered to patients who have one or no copies of the ApoE4 gene, as individuals with two copies face a heightened risk of ARIA. This limitation reflects the regulatory body's commitment to ensuring patient safety while still providing access to potentially life-altering treatment.
In January 2025, the EC requested the CHMP to reassess new safety data that emerged after the positive opinion. Following a thorough review, the CHMP reaffirmed its positive opinion in February, ultimately paving the way for the EC’s final decision.
Christopher Viehbacher, president and CEO at Biogen, highlighted the significance of this approval, stating, “The approval of Leqembi by the EC marks the thirteenth approval of this important medicine, which has already benefitted thousands of patients in the US, Japan, and other regions of the world. This is a landmark advancement in a field where there has been no or little innovation in the past 20 years.”
As for the commercial landscape, Leqembi is already approved in several countries outside Europe, including the United States, where it received full FDA approval in July 2023. The drug has also been endorsed in China, Japan, and Great Britain, among others. However, Biogen’s shares have taken a hit, plunging 23.5% year-to-date compared to a 6.5% decline in the industry.
Despite the financial challenges, the launch of Leqembi in Europe represents a crucial growth opportunity for both Biogen and Eisai. Keisuke Naito, Eisai’s chief operating and growth officer, indicated that improvements in awareness, diagnostic guidelines, and a new dosing schedule recently approved in the US should help bolster future growth.
The approval of Leqembi comes at a time when the need for effective Alzheimer’s treatments is more pressing than ever. Currently, an estimated 6.9 million people in Europe are affected by Alzheimer’s disease, while mild cognitive impairment due to AD impacts around 15.2 million individuals. With the aging population, these numbers are expected to rise, further underscoring the importance of innovative therapies.
The Clarity AD trial, which provided the data supporting Leqembi’s approval, was a landmark study that showcased the drug's potential to alter the course of the disease. The trial results indicated that Leqembi not only slowed cognitive decline but also improved activities of daily living, as evidenced by a 33% reduction in decline compared to placebo on the AD Cooperative Study-Activities of Daily Living Scale for Mild Cognitive Impairment.
However, the approval also brings to light the ongoing concerns regarding the drug's safety profile. The most common adverse events observed during the Clarity AD trial included infusion-related reactions, headaches, and cerebral edema. As Eisai moves forward, the company will work closely with reimbursement authorities to ensure that eligible patients have timely access to the treatment while also monitoring safety closely.
In summary, the approval of Leqembi by the European Commission is a significant step forward in the treatment landscape for Alzheimer’s disease. It not only provides hope for patients and their families but also represents a critical advancement in a field that has seen little innovation in recent years. As Biogen and Eisai prepare for the drug's launch in Europe, the focus will be on ensuring patient safety and maximizing the therapeutic potential of this groundbreaking medication.
