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Abstract Details

Achieving an optimal profile for immunotherapy of alpha-synucleinopathies: Rational generation of monoclonal antibodies selective for pathogenic forms of alpha-synuclein
Movement Disorders
P10 - Poster Session 10 (5:30 PM-6:30 PM)
3-005

Generate antibodies that can selectively target pathogenic forms of alpha-synuclein (A-syn) for optimal safety and efficacy.

A-syn oligomers and soluble protofibrils have been implicated in the neurotoxicity and cell-to-cell propagation of pathogenic A-syn in synucleinopathies, including Parkinson’s disease, dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). We therefore sought to generate antibodies against epitopes selectively exposed on these toxic species of A-syn. The advantage of this approach, as opposed to pan-A-syn reactivity, lies in preserving normal A-syn function and minimizing the diversion of active antibody from the target by the more abundant non-toxic forms of the protein in the blood and CNS.
We used a computational modeling approach (Collective Coordinates) to identify conformational epitopes predicted to be exposed on A-syn oligomers, and to a lesser extent fibril fragments/protofibrils, but not on large insoluble fibrils, physiological tetramers, or A-syn monomers. Cyclic peptide scaffolds that best reproduced the conformational epitopes were used to immunize mice and generate monoclonal antibodies that were then screened for the desired binding profile and biological activity in vitro.

Antibodies that selectively bind toxic A-syn oligomers and soluble sonicated fibrils, while avoiding monomers and physiologic tetramers, were identified using surface plasmon resonance (SPR).  These antibodies also avoided non-productive binding to Lewy bodies as determined by immunohistochemistry.  Recognition of native, toxic A-syn aggregates in brain extracts from DLB and MSA patients was confirmed by SPR and dot blot.  In vitro, the antibodies inhibited the seeding activity of sonicated pre-formed fibrils (PFFs) in a thioflavin-T fluorescence-based aggregation assay.  In neuronal cultures, the antibodies protected primary rat dopaminergic neurons from toxic A-syn oligomers, reduced the uptake of PFFs, and inhibited the induction of pathogenic phosphorylated aggregates of A-syn.

Rational computational modeling based on A-syn biology allowed for epitope prediction and generation of antibodies selective for pathogenic A-syn.
Authors/Disclosures
Johanne M. Kaplan, PhD (ProMIS Neurosciences)
PRESENTER 		Dr. Kaplan has received personal compensation for serving as an employee of ProMIS Neurosciences. Dr. Kaplan has stock in ProMIS Neurosciences. Dr. Kaplan has received intellectual property interests from a discovery or technology relating to health care.
Ebrima Gibbs, Bsc, BMLSc, MSc (University of British Columbia) Dr. Gibbs has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Promis Neurosciences.
Beibei Zhao Beibei Zhao has received intellectual property interests from a discovery or technology relating to health care.
No disclosure on file
No disclosure on file
No disclosure on file
Neil Cashman, MD (University of British Columbia) Dr. Cashman has received personal compensation for serving as an employee of ProMIS Neurosciences. Dr. Cashman has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for IONIS. Dr. Cashman has stock in ProMIS Neurosciences. The institution of Dr. Cashman has received research support from ProMIS Neurosciences. Dr. Cashman has received intellectual property interests from a discovery or technology relating to health care.