A Systematic Review of the Efficacy and Safety of Anti-amyloid Monoclonal Antibodies in Alzheimer's Disease.

Monoclonal antibody (mAb) therapies targeting amyloid-beta (Aβ) plaques have gained prominence over the past decade as potential disease-modifying treatments for Alzheimer's disease (AD), leading to major regulatory approvals and global debate. Nonetheless, the central question persists: does this emerging therapy have a justified role in the treatment protocol for AD? This systematic review evaluates the efficacy and safety of these agents across phase II and III clinical trials conducted in the past decade (2014-2024), aligning with the timeline when disease-modifying therapies gained momentum. A systematic search was performed across PubMed and the Cochrane Library to identify phase II and III randomized controlled trials (RCTs) conducted between January 2014 and December 2024. The inclusion criteria focused on studies that evaluated cognitive outcomes using scales such as the Clinical Dementia Rating-Sum of Boxes (CDR-SB), Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), and Mini-Mental State Examination (MMSE). Additionally, trials assessing biomarkers, including CSF measures and PET imaging, were included. Safety outcomes, particularly amyloid-related imaging abnormalities (ARIA), were also systematically analyzed. Due to heterogeneity in outcome measures, a narrative synthesis was conducted. Sixteen RCTs met the inclusion criteria. Lecanemab reduced amyloid burden with 81% of patients achieving amyloid-negative PET scans (Clarity AD trial) and showed a 27% reduction in cognitive decline on the ADCOMS scale. While statistically significant, the 27% ADCOMS (Alzheimer's Disease Composite Score) reduction warrants comparison to MCID (minimal clinically important difference) thresholds (e.g., ~0.5-1.0 points for CDR-SB in early AD) to assess real-world impact. Donanemab demonstrated 76% plaque clearance and a 35% slowing in cognitive decline in early AD patients. Aducanumab showed dose-dependent effects on plaque clearance but had inconsistent cognitive outcomes and higher ARIA rates. Recent mAb trials provide promising evidence for disease modification in early AD stages, particularly with lecanemab and donanemab. However, variability in cognitive outcomes and safety concerns warrant cautious interpretation and long-term validation.