Structural and Functional Determinants of ARIA-H Risk in Anti-Amyloid Monoclonal Antibodies: A Comparative Mechanistic Framework for Alzheimer's Immunotherapy Development.

Introduction: Amyloid-beta-targeting monoclonal antibodies (mAbs) for Alzheimer's disease frequently induce amyloid-related imaging abnormalities with hemorrhage (ARIA-H), yet systematic comparisons of ARIA-H incidence across therapeutic agents remain limited. Post-approval research prioritizes dosing over mechanism, leaving unresolved whether ARIA-H variations originate from intrinsic mAb properties. We address two gaps: comparative ARIA-H risk stratification among clinically available/investigational mAbs, and elucidation of structural/functional features influencing ARIA-H susceptibility.

Methods: A systematic comparison of seven mAbs (donanemab, aducanumab, bapineuzumab, lecanemab, gantenerumab, crenezumab, solanezumab) was conducted, analyzing clinical trial data and molecular characteristics.

Results: ARIA-H incidence ranked as follows (highest to lowest): donanemab > aducanumab > bapineuzumab > lecanemab > gantenerumab > crenezumab > solanezumab. Five mAb-specific determinants emerged: (1) Types of Aβ Binding: Enhanced clearance of mature amyloid plaques correlated with elevated ARIA-H risk. (2) Polymer binding Affinity: Reduced small oligomer-binding capacity predicted higher ARIA-H incidence. (3) Epitope location: N-terminal-targeting mAbs showed greater ARIA-H incidence vs. mid/C-terminal binders. (4) Fc region structure: IgG4-based constructs showed higher ARIA-H incidence than IgG1 analogs. (5) Clearance kinetics: Rapid attainment of amyloid reduction thresholds amplified ARIA-H incidence.

Discussion: We identify a risk hierarchy for ARIA-H among anti-Aβ mAbs and link specific mAb biophysical properties-Aβ binding type, affinity for soluble oligomers, epitope specificity, Fc structure, and plaque clearance dynamics-directly to ARIA-H pathogenesis.

Conclusion: These findings establish a mechanistic framework for ARIA-H risk and provide concrete molecular predictors to guide antibody engineering strategies. Prioritizing mAbs with controlled amyloid clearance, C-terminal binding domains, and IgG1 frameworks may enhance therapeutic safety, advancing precision immunotherapy for Alzheimer's disease.