Biogen(US:BIIB) Globenewswire·2025-12-03 23:10Core Insights - Long-term treatment with LEQEMBI may delay the progression of Alzheimer's disease from Mild Cognitive Impairment (MCI) to moderate Alzheimer's by up to 8.3 years in low-amyloid patients who start treatment early [1][5]. Group 1: Treatment Efficacy - LEQEMBI targets both protofibrils and amyloid plaques, which are key contributors to Alzheimer's disease progression [2]. - Early initiation of LEQEMBI treatment is associated with greater delays in disease progression, with each additional year on treatment further extending the delay [4]. - In untreated patients, the time to progress from MCI to mild Alzheimer's was 7.2 years, while LEQEMBI treatment extended this to 9.7 years, resulting in a time savings of 2.5 years [5]. - For low-amyloid patients, the time to progression from MCI to mild Alzheimer's was 13.2 years with LEQEMBI, indicating a time savings of 6.0 years [5]. Group 2: Safety and Administration - The subcutaneous formulation of LEQEMBI has shown bioequivalence to intravenous dosing, maintaining efficacy and safety [6][7]. - Systemic infusion reactions were significantly lower in patients receiving the subcutaneous formulation compared to those receiving intravenous treatment [8]. - The incidence of amyloid-related imaging abnormalities (ARIA) was comparable between subcutaneous and intravenous administration, with ARIA-E observed in 13% of LEQEMBI patients [17]. Group 3: Regulatory and Market Position - LEQEMBI has been approved in 51 countries, including Japan and the United States, and is under regulatory review in 9 additional countries [35]. - The U.S. FDA approved the subcutaneous maintenance dosing of LEQEMBI in August 2025, with a supplemental Biologics License Application for initiation treatment completed in November 2025 [1][35]. - Eisai leads the development and regulatory submissions for LEQEMBI globally, with Biogen co-commercializing the product [9][38].