Prana Biotechnology's (PRAN) phase II study of PBT2 in Alzheimer's disease failed, the company announced Monday morning.
Shares of Prana are down 75% to $2.51 in pre-market trading.
The experimental PBT2 did not meet the study's primary endpoint of a statistically significant reduction in levels of beta amyloid plaque in the brains of patients with prodromal or mild Alzheimer's, as measured using PET imaging.
PBT2 also failed to demonstrate an improvement in brain metabolic activity, cognition or function compared to placebo.
A previous phase II study of PBT2 in Huntington's disease also failed, although Prana insists the study was positive and plans to conduct a confirmatory study in the future.