Novel Monoclonal Antibody Detects Small Aβ Oligomers More Sensitively Than Lecanemab in Alzheimer's Disease CSF, Serum and Culture Media

Whereas lecanemab is an effective plaque-clearing immunotherapy that robustly detects higher-order Aβ aggregates in AD brain, its preferred Aβ targets are present at very low levels in biofluids. Our results demonstrate that 71A1 detects low-n, diffusible Aβ oligomers that predominate in CSF, serum, and neuronal media that associate with AD-related pathology. Together, these findings indicate that Aβ oligomer populations distribute differently in brain tissue versus biofluids and inform the selection of assays for monitoring oligomers during AD progression and treatment. ANN NEUROL 2026.