An Open Label Study of V81444 Using Positron Emission Tomography to Assess Occupancy of Brain Adenosine A2A Receptors & Functional & Perfusion MRI to Explore Effects on Regional Brain Activity & Perfusion in Healthy Male Volunteers

In this Phase I, single-centre, open-label, adaptive, single-dose study at multiple dose levels, the relationship between dose and plasma concentration of orally administered V81444 to brain A2A RO was investigated in 6 healthy male volunteers. In addition, the effects of V81444 on regional brain activity and perfusion during tests of cognitive function, and the safety and tolerability of V81444 were assessed. For each subject, the study consisted of a screening visit, a baseline visit, a treatment period, and a safety follow-up visit. The dose of V81444 and timing of scans performed were defined in the protocol for the first 2 subjects only. The dose, nature and timings of assessments for subsequent subjects were determined based on review of emerging receptor binding, pharmacokinetic (PK), pharmacodynamic (PD) and safety information.

In each treatment period, subjects were admitted to the unit on the day before dosing (Day -1), received a single oral dose of V81444 on Day 1 and, subject to satisfactory medical review, were discharged a minimum of 12 h after dosing. Overall, 3 doses of V81444 were assessed (250 mg, 50 mg, and 100 mg), with 2 subjects included at each dose level. PD assessments were performed at baseline and after each dose of V81444 using PET (with the A2A radioligand, to measure brain A2A RO, as well as MRI techniques to investigate the effects of V81444 on regional brain activity and perfusion during cognitive function tests. PK parameters were assessed by assay of V81444 concentration in plasma. Safety and tolerability were assessed by monitoring physical examination findings, adverse events (AEs), vital signs, 12 lead electrocardiogram (ECG) and clinical laboratory safety tests.