Efficacy assessment of an active tau immunotherapy in Alzheimer's disease patients with amyloid and tau pathology: a post hoc analysis of the "ADAMANT" randomised, placebo-controlled, double-blind, multi-centre, phase 2 clinical trial.

Background: Tau pathology correlates with and predicts clinical decline in Alzheimer's disease. Approved tau-targeted therapies are not available.
Methods: ADAMANT, a 24-month randomised, placebo-controlled, parallel-group, double-blinded, multicenter, Phase 2 clinical trial (EudraCT2015-000630-30, NCT02579252) enrolled 196 participants with Alzheimer's disease; 119 are included in this post-hoc subgroup analysis. AADvac1, active immunotherapy against pathological tau protein. A machine learning model predicted likely Amyloid+Tau+ participants from baseline MRI.
Statistical Methods: MMRM for change from baseline in cognition, function, and neurodegeneration; linear regression for associations between antibody response and endpoints.
Results: The prediction model achieved PPV of 97.7% for amyloid, 96.2% for tau. 119 participants in the full analysis set (70 treatment and 49 placebo) were classified as A+T+. A trend for CDR-SB 104-week change (estimated marginal means [emm] = -0.99 points, 95% CI [-2.13, 0.13], p = 0.0825]) and ADCS-MCI-ADL (emm = 3.82 points, CI [-0.29, 7.92], p = 0.0679) in favour of the treatment group was seen. Reduction was seen in plasma NF-L (emm = -0.15 log pg/mL, CI [-0.27, -0.03], p = 0.0139). Higher antibody response to AADvac1 was related to slowing of decline on CDR-SB (rho = -0.10, CI [-0.21, 0.01], p = 0.0376) and ADL (rho = 0.15, CI [0.03, 0.27], p = 0.0201), and related to slower brain atrophy (rho = 0.18-0.35, p < 0.05 for temporal volume, whole cortex, and right and left hippocampus).
Conclusions: In the subgroup of ML imputed or CSF identified A+T+, AADvac1 slowed AD-related decline in an antibody-dependent manner. Larger anti-tau trials are warranted.
Funding: AXON Neuroscience SE.
Competing Interests: Declaration of interests Nick Cullen received personal fees from AXON Neuroscience SE. All authors affiliated with AXON NEUROSCIENCE SE or one of its subsidiaries received salary from their respective companies. Jozef Hanes, Eva Kontsekova, and Branislav Kovacech report patents with AXON Neuroscience R&D Services SE. Petr Novak received payments from F. Hoffmann-La Roche AG. The investigators’ institutions received reimbursement on a per-patient per-visit basis. Duygu Tosun’s institution received payments from AXON Neuroscience for image processing, and payments to the institution from Siemens Medical Solutions USA, Inc., Takeda Pharmaceutical Company Ltd., DOD WW81XWH-19-1-0669, NIH/NIA U19AG024904, NIH/NIA U01AG068057, NIH/NIA U24AG074855, NIH/NIA R01AG058676. Reinhold Schmidt has received personal fees and honoraria for image analyses from AXON NEUROSCIENCE. Stefan Ropele reports no conflict of interest. Bengt Winblad reports personal fees for taking part in Scientific Advisory Board meetings and Data Safety Management Board meetings from AXON NEUROSCIENCE, and from Alzinova DSMB and Artery TX SAB. Dr. Feldman reports a service agreement between Axon Neuroscience and UCSD for consulting and travel with all payments to UCSD and no personal funds received. Other activities to report include: grant funding from Annovis (QR Pharma), Vivoryon (Probiodrug), AC Immune, and LuMind; service agreements for consulting activities with LuMind, Genentech (DSMB), Roche/Banner (DMC), Tau Consortium (SAB), Samus Therapeutics, Biosplice Therapeutics, Novo Nordisk Inc., Janssen Research & Development LLC, and Arrowhead Pharmaceuticals with no personal funds received and all payments to UCSD. He also reports a philanthropic donation to UCSD from the Epstein Family Alzheimer's Disease Collaboration for therapeutic research in AD.
(Copyright © 2023 AXON NEUROSCIENCE SE. Published by Elsevier B.V. All rights reserved.)