Kinetic fingerprints differentiate the mechanisms of action of anti-Aβ antibodies

The effects of four antibodies on the aggregation pathway of A beta are examined via an in-depth kinetics approach, revealing the specific molecular steps affected by each antibody. The amyloid cascade hypothesis, according to which the self-assembly of amyloid-beta peptide (A beta) is a causative process in Alzheimer's disease, has driven many therapeutic efforts for the past 20 years. Failures of clinical trials investigating A beta-targeted therapies have been interpreted as evidence against this hypothesis, irrespective of the characteristics and mechanisms of action of the therapeutic agents, which are highly challenging to assess. Here, we combine kinetic analyses with quantitative binding measurements to address the mechanism of action of four clinical stage anti-A beta antibodies, aducanumab, gantenerumab, bapineuzumab and solanezumab. We quantify the influence of these antibodies on the aggregation kinetics and on the production of oligomeric aggregates and link these effects to the affinity and stoichiometry of each antibody for monomeric and fibrillar forms of A beta. Our results reveal that, uniquely among these four antibodies, aducanumab dramatically reduces the flux of A beta oligomers.