Takeda Pharmaceutical Company Ltd. / AC Immune SA

Alzheimer's disease (early and Down syndrome-associated)

6.9M US cases/yr · $13.0B Anti-amyloid MAb peak global sales analyst consensus (Leqembi + Kisunla class) · 2200 Takeda-AC Immune deal size (USD MM, $100M upfront + $2.1B milestones)

Disease Overview

Alzheimer's disease (AD) affects approximately 6.9 million Americans aged 65+ in 2024 and is projected to nearly double to 13.8 million by 2060 (Alzheimer's Association 2024 Facts and Figures). AD is the seventh leading cause of US death and the costliest chronic disease to Medicare/Medicaid, with total 2024 care costs estimated at $360 billion. The last three years have reshaped the category: Biogen/Eisai's Leqembi (lecanemab) received traditional FDA approval July 2023 and Lilly's Kisunla (donanemab) was approved July 2024 — both are anti-Abeta monoclonal antibodies requiring IV infusion, MRI monitoring for ARIA (amyloid-related imaging abnormalities), and restricted use in ApoE4 homozygotes. Neither has achieved expected commercial trajectory: 2024 Leqembi sales were ~$87M, with complex logistics, narrow eligible population, and modest clinical benefit (27% relative slowing of decline on CDR-SB) cited as gating factors. Active immunotherapies (vaccines) against Abeta offer a theoretical advantage of chronic, low-cost dosing — a self-boosting immune response versus monthly infusion — and potentially better ARIA risk profile. Down syndrome-associated AD affects essentially 100% of individuals with Down syndrome by age 40, representing ~200,000 US adults with a distinct regulatory pathway.

Competitive Landscape

The active anti-amyloid immunotherapy class sits parallel to passive monoclonals. Passive anti-Abeta MAbs (approved): Leqembi (lecanemab, Eisai/Biogen) — first traditional approval 2023, IV q2w; Kisunla (donanemab, Lilly) — approved July 2024, IV q4w with limited-duration dosing. Anti-Abeta MAb (discontinued): Aduhelm (aducanumab, Biogen) — withdrawn 2024. Active Abeta immunotherapies: ACI-24.060 (AC Immune / now Takeda optioned, Phase 1b/2 ABATE study); ABvac40 (Araclon Biotech, C-terminal Abeta40 vaccine, Phase 2). Anti-tau programs: E2814 (Eisai, intrathecal tau MAb Phase 2/3 DIAN-TU), JNJ-63733657 / posdinemab (J&J/Genentech collab, Phase 2); Bepranemab (UCB/Roche). Secretase and other mechanisms: semorinemab (Genentech, discontinued Phase 2); BIIB080 (tau ASO, Biogen/Ionis Phase 2). The active immunotherapy hypothesis is that a sustained, self-renewing antibody response could outperform passive MAb infusion economically and reduce ARIA if epitope specificity is narrowed to pyroglutamate or oligomeric Abeta, which is ACI-24.060's stated differentiation.