Randomized Phase I Trial of the α-Synuclein Antibody Lu AF82422

Background: Immunotherapy targeting pathological alpha-synuclein (alpha-syn) species is a promising strategy for slowing disease progression in neurodegenerative synucleinopathies, including Parkinson's disease (PD). Objective: The aim was to evaluate the safety, tolerability, pharmacokinetics, and target engagement of ascending doses of Lu AF82422. Methods: In this first-in-human study (NCT03611569), healthy participants (18-55 years, cohort A) and patients with PD (40-80 years, Hoehn and Yahr stage <= 3, cohort B) were enrolled in ascending-dose cohorts and randomly assigned to receive single intravenous infusions of Lu AF82422 (cohorts A1-A6: 75, 225, 750, 2250 4500, and 9000 mg, respectively; cohorts B1 and B2: 2250 and 9000 mg, respectively) or placebo. Participants were monitored during a 12-week observational period. Results: Overall, single intravenous infusions of Lu AF82422 were safe and well tolerated, and no serious adverse events (AE) were observed; the most common AEs were related to the study on lumbar punctures, headache, and common infections. Lu AF82422 concentrations (in plasma and cerebrospinal fluid [CSF]) increased in a dose-proportional manner with no observable differences between cohorts; mean plasma half-life was 700 h. Plasma concentrations of Lu AF82422 had an immediate, concentration-dependent lowering effect on the plasma concentration of free alpha-syn and on the ratio of free to total alpha-syn in all cohorts and lowered the free-to-total alpha-syn ratio in CSF in the high-dose PD cohort. Conclusions: The safety and pharmacokinetic profile of Lu AF82422 were appropriate for further clinical development, and results indicated peripheral target engagement. The central target engagement observed in participants with PD indicates that the doses of Lu AF82422 tested may provide CSF concentrations sufficient to target aggregated forms of alpha-syn. (c) 2024 H. Lundbeck A/S. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.