To develop small molecules which inhibit the key molecular mechanisms responsible for the generation of toxic alpha-synuclein oligomers in Parkinson’s Disease (PD) and other synucleinopathies with precision, from in vitro to in vivo systems.

Oligomeric forms of alpha-synuclein have been shown to have wide-ranging neurotoxicity and underlie the onset and progression of PD. They bind to membranes, receptors and organelles, disrupt metabolic and neuronal functional pathways and ultimately cause neuronal death, but are challenging to target with conventional drug discovery approaches. Using the framework of “chemical kinetics”, we mapped the mechanisms of oligomer generation: primary, lipid-induced nucleation (where lipid membranes catalyse the formation of oligomers by several monomers) and secondary nucleation (where oligomer formation is catalysed by larger alpha-synuclein aggregates).

Compounds were initially characterized in in vitro protein aggregation assays starting from monomeric recombinant human alpha-synuclein. Compounds were then optimised for potency, oral pharmacokinetics and brain penetration. Following this optimisation, compounds were tested in a range of cellular and in vivo systems, including iPSC-derived cortical and dopaminergic neurons, and the Line-61 transgenic mouse model.

Our compounds were able to inhibit both of the key processes generating alpha-synuclein oligomers by >96% in vitro, and retained potency when reactions were seeded with human PD brain tissue. Efficacy was also demonstrated in iPSC derived cells treated with compound, reducing oligomers and pS129 aggregates and improving functional markers. In the Line 61 mouse model, the same compound substantially reduced pS129 aggregate levels (-44% vs vehicle) with on-target reduction of oligomers (-25% vs. vehicle) after dosing at 15 mg/kg for 10 weeks.

Our small molecule inhibitors of alpha-synuclein oligomer generation show a robust effect across systems from in vitro, to cellular and in vivo models, demonstrating both target engagement and functional benefit in translational models.