Cassava Sciences said that its drug did not significantly reduce cognitive decline in 1,900 people with mild to moderate Alzheimer’s disease.

(Reuters) -Cassava Sciences said on Monday it will stop all trials of its Alzheimer's disease drug after it failed a late-stage study, sending shares of the drug developer plummeting more than 80% before the bell.

Cassava Sciences stock collapsed after an Alzheimer’s drug the company was testing failed to significantly help participants in a clinical trial. The stock plummeted 84% to $4.15 Monday after reporting that a Phase 3 trial meant to demonstrate the efficacy of a medication called Simufilam fell short of key milestones.

Alector Therapeutics, working with AbbVie, was testing whether modulating immune cells in brain would slow Alzheimer's disease. Its drug failed the Phase 2 trial.

Cassava Sciences (NASDAQ:SAVA) stock has plummeted ~86% after announcing that Alzheimer's disease candidate simufilam did meet its co-primary endpoints in a phase 3 trial. Those endpoints were change in cognition and function from baseline to the end of week 52,