Eisai and Biogen's Alzheimer's Drug Leqembi Secures European Approval After Regulatory Hurdles

In a significant development for the pharmaceutical industry, Eisai and Biogen's Alzheimer's disease medication Leqembi (lecanemab) has finally received marketing authorization from the European Commission (EC). This approval marks the end of a complex regulatory journey in Europe and opens up a new market for the drug, albeit with certain restrictions.

European Approval and Regulatory Journey

The EC's decision to approve Leqembi comes after months of regulatory back-and-forth. Initially rejected by the European Medicines Agency's (EMA) Committee for Medicinal Products for Human Use (CHMP) in July 2024, the drug underwent a reexamination process that ultimately led to a positive outcome. The final approval, however, comes with strict conditions and is limited to a specific patient population.

Leqembi is now authorized for the treatment of mild cognitive impairment in early-stage Alzheimer's patients in Europe. The eligible patient group is restricted to those with one or no copies of the ApoE4 gene and who have amyloid beta plaques in their brain. This limitation is due to the higher risk of amyloid-related imaging abnormalities (ARIA), including brain swelling or bleeding, in patients with two copies of the ApoE4 gene.

Market Implications and Global Reach

The European approval of Leqembi is a crucial milestone for Eisai and Biogen, as it expands the drug's global footprint. Prior to this decision, Leqembi had already gained approval in several countries, including the United States, Japan, China, Great Britain, and Mexico.

Despite its initial FDA approval in 2023, Leqembi's U.S. launch has been relatively slow. In the third quarter of Eisai's 2024 fiscal year, which ended March 31, the drug generated approximately 13.3 billion Japanese yen ($87 million) in worldwide sales. However, Eisai's chief operating and growth officer, Keisuke Naito, expressed optimism about the drug entering a "growth expansion phase," citing improvements in awareness, diagnostic guidelines, and a new dosing schedule recently approved in the U.S.

Competitive Landscape and Future Outlook

Leqembi's European approval sets it apart from its rival, Eli Lilly's Alzheimer's medication Kisunla, which was rejected by European regulators in March 2025 due to similar ARIA-related safety concerns. This development positions Leqembi as the first drug of its kind to receive approval in the European market.

As Eisai and Biogen prepare to launch Leqembi in Europe, the pharmaceutical industry will be closely watching its performance and impact on the Alzheimer's treatment landscape. The restricted patient population and required safety measures will likely influence the drug's uptake and market penetration in the region.