Conclusion
The results support continued evaluation of avagacestat in an elderly target population with predementia and mild to moderate Alzheimer's disease.
Methods
Thirty-three young men were assigned to four serial dose groups of avagacestat 15, 50, 100 or 150 mg (n = 6-7 per dose), or placebo (n = 2 per dose panel; 8 subjects total) once daily for 28 days. Elderly men and women were assigned to serial dose groups of avagacestat 50 mg and then 100 mg (n = 7 men, 6 women) or placebo (n = 2 men, 2 women) once daily for 14 days per dose level.
Results
Avagacestat was rapidly absorbed, had a terminal elimination half-life of 38-65 h, and reached a steady-state concentration by day 10 of daily dosing. Exposure in young subjects increased in proportion to dose. There were no apparent differences in steady-state area under the plasma concentration-time curve between young and elderly subjects; however, elderly subjects demonstrated a higher maximum plasma concentration for avagacestat. Doses of avagacestat >50 mg/day reduced steady-state trough concentrations of CSF Aβ(1-38), Aβ(1-40) and Aβ(1-42) in a dose-dependent fashion over 28 days of daily dosing. There were no signs of potential Notch-related dose-limiting toxicities.