Clinical trial outcomes, 2016 – 2024
Nine Phase-II and Phase-III trials of anti-amyloid monoclonal antibodies (2016 – 2024) are clustered by target epitope and endpoint family. Two positive trials (lecanemab, donanemab) share a common plaque-reduction mechanism but diverge on cognitive endpoint strength. The review flags a gap in head-to-head comparison and a consistent under-powering for ApoE4 carriers.
The first generation of anti-amyloid mAbs targeted the central domain and consistently failed on cognitive endpoints despite measurable target engagement [al. 14] [al. 18] [al. 21].
Aducanumab's N-terminal-binding variant demonstrated the first robust, dose-dependent plaque reduction in vivo [al. 16], although the Phase-3 program produced conflicting readouts [al. 22] that complicate interpretation.
Selectivity for aggregated plaque produced the first unambiguous cognitive signals: 27% slowing in Clarity-AD [al. 23] and 35% functional preservation in TRAILBLAZER-ALZ 2 [al. 23], building on an earlier Phase-2 dose-finding [al. 21].
ARIA-H and ARIA-E remain the dose-limiting toxicity across this class [al. 11]. Every positive trial reports ARIA as the primary safety signal; future trial design will be constrained by ARIA-adjusted dosing.
Both were FDA-approved in 2023; no published trial compares them directly. The non-inferiority question is currently answered by meta-analysis only.
Every positive trial shows reduced effect in ApoE4 homozygotes; no trial is powered to detect this subgroup as primary. A prespecified ApoE4-carrier trial is the obvious next step.