Biogen(US:BIIB) Globenewswire·2025-12-02 21:40Core Insights - The latest data presented at the 18th Clinical Trials on Alzheimer's Disease Conference confirms the pharmacological effect of lecanemab (LEQEMBI) on Aβ protofibrils in cerebrospinal fluid, marking a significant advancement in understanding how lecanemab slows Alzheimer's disease progression [1][7]. Group 1: Clinical Study Findings - A large-scale clinical study demonstrated that lecanemab binds to Aβ protofibrils, which can now be measured in cerebrospinal fluid, providing insights into its mechanism of action [1][5]. - In a CSF sub-cohort of the Phase III Clarity AD study, the total PF concentration in the placebo group increased by 19% at 12 months and 29% at 18 months, while the lecanemab group showed a 59% increase at 12 months and a 45% increase at 18 months, with a statistically significant difference at 12 months (p=0.0126) [4][6]. - The increase in total CSF PF with lecanemab treatment suggests effective target engagement and mobilization of PF from the brain parenchyma into the CSF, indicating a pharmacodynamic effect [5]. Group 2: Mechanism of Action - Lecanemab is unique in its dual action of targeting both protofibrils and amyloid plaques, which may influence downstream tau pathology [2][7]. - The treatment with lecanemab resulted in a significant reduction in neurotoxicity, as evidenced by the disappearance of correlations between CSF PF changes and neurodegeneration biomarkers in the lecanemab group [6]. Group 3: Regulatory and Commercialization Aspects - Eisai leads the global development and regulatory submissions for lecanemab, with both Eisai and Biogen co-commercializing and co-promoting the product [7][36]. - Lecanemab has received approval in 51 countries and regions, including Japan, the United States, and Europe, and is under regulatory review in 9 additional countries [32].