Epitope Sequence and Modification Fingerprints of Anti-Aβ Antibodies

A hallmark of Alzheimer’s disease (AD), the most common form of dementia, is the progressive accumulation of amyloid-beta (Aβ) peptides across distinct brain regions. Anti-Aβ antibodies (Aβ-Abs) that bind specific Aβ variants are essential research tools. Furthermore, the monoclonal Aβ-Abs Aducanumab, Lecanemab, and Donanemab have recently gained approval as the first disease-modifying therapeutics for early AD. In this study, we systematically determined on peptide microarrays the exact binding epitopes of 20 Aβ-Abs, including biosimilars of Aducanumab, Lecanemab and Donanemab. Precise Aβ-sequence and modification requirements were resolved through deep mutational scans and synthetically modified peptide libraries. To address the potential limitations of peptide microarrays employing short Aβ fragments, the observed monovalent Aβ-Ab reactivities were further studied using biochemical approaches, complementary in vitro analysis of Aβ-Ab binding to oligomeric and aggregated Aβ, as well as immunohistochemical staining of patient-derived AD brain samples. The data identifies Aβ-Abs that preferentially recognize critical truncation and modification variants as well as gain and loss of binding mutants in familial AD. Our work provides insights into the mode of binding of currently available Aβ-Ab biosimilars and further classifies the immunological tools for detecting and discriminating distinct Aβ truncations, mutational variants and post-transcriptionally modified derivatives. We expect that this comprehensive resource on Aβ-Ab sequence and modification selectivity will not only advance fundamental research on AD but potentially also support the development of improved diagnostic tools and therapeutic strategies.