Functional activity of the muscarinic positive allosteric modulator VU319 during a Phase 1 Single Ascending Dose study

Introduction The development of neurotransmitter based cognitive enhancers for Alzheimer's disease have focused recently on allosteric modulation, as a way of reducing potential drug-limiting toxicities that have been the hallmark of earlier orthosteric compounds. VU319 is an investigational positive allosteric modulator of the M1 muscarinic acetylcholine receptor that has recently finished initial testing in healthy volunteers. Cognitive tasks and event-related potentials (ERPs) have been used during the randomized, double-blind, placebo controlled Single Ascending Dose (SAD) study of VU319. This presentation includes both data from the initial SAD study, and the Food Effect substudy. The main pharmacodynamic objectives of the SAD were to identify early markers of functional engagement. Following the ascending dose cohorts, a Food Effect substudy was conducted to assess whether there was any change in the cognitive performance if VU319 was dosed with food compared to in a fasted state. Methods VU319 was given orally to 52 healthy volunteers aged 18-55?years. The SAD study tested 40 participants in five dose escalating cohorts of eight participants, in which six received VU319 and two received placebo. The Food Effect substudy consisted of 12 participants, in which ten received oral VU319 and two received placebo. The five doses for the SAD study were 60, 120, 240, 400 and 600mg. Participants in the Food Effect substudy received VU319 at a single dose of 120mg. For the 5 cohorts of the SAD study, all participants were dosed in a fasted stated. In contrast, all 12 participants in the Food Effect substudy completed were dosed twice; once fasted, and once following breakfast. Cognitive and electrophysiological tasks were examined pre-dosing and at 5?hours post-dose. The tasks were selected for their sensitivity to cholinergic tone. Cognitive tasks tested spatial and sustained attention, episodic and working memory, perceptual vigilance and psychomotor speed. Recorded ERP examined auditory and visual discrimination using oddball tasks, and an incidental memory task in which participants passively observed novel and repeated complex images. Results The analysis showed a trend for improvements in cognitive and ERP performance on the higher doses of VU319 compared to placebo. Participants on the highest dose of VU319 responded significantly faster to targets on the continuous performance test compared to participants on placebo (p = 0.03, effect size d = 1.2). Additionally, on the incidental memory task, participants who received the higher two doses of VU319 exhibited larger P300 amplitudes compared to placebo, when present with repeated compared to novel images (d > 0.8). Examination of the relationship between plasma levels of VU319 and cognitive performance showed that the response time on the continuous performance task decreased in relation to increasing concentration of VU319 in the bloodstream. Conclusions We conclude that these results demonstrate potential enhancement of the cholinergic system functioning in healthy adults following a single dose of VU319. These results provide an indication of the potential measures that are sensitive to cognitive activity by VU319 and therefore provide a potential framework to examine the cognitive impact of multiple doses of VU319 in AD patients. This research was funded by: This work was supported by the following grants: VKC Hobbs Discovery Grant 4-04-218-9745, Alzheimer's Association PCTR-16-383171; NICHD U54 HD083211, NCATS UL1 TR000445, 2RO1MH082867, R01MH073676, R01MH86601, MH087965, MH093366.