(Reuters) -Cassava Sciences said 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 83% in early trading on Monday.

The Cassava Sciences story ended Monday exactly as many knew it would — with the company’s experimental drug for Alzheimer’s disease, simufilam, failing a clinical trial.

Cassava Sciences shares are plunging in premarket trading and are losing most of their value after the biotech firm said its experimental Simufilam drug aimed at treating Alzheimer’s disease failed to show a “significant reduction in cognitive or functional decline” during the Phase 3 trial of the treatment.

Cassava Sciences’ phase 3 Alzheimer’s disease trial has missed its co-primary endpoints. With the study also missing secondary and exploratory biomarker endpoints, the biotech has pulled the plug on another phase 3 trial and an open-label extension.

Cassava Sciences' simufilam failed a Phase III trial for Alzheimer's disease, likely marking the end of a drug surrounded by allegations of poorly done and fraudulent research.

Cassava Sciences (SAVA) stock faces uncertainty after a major late-stage trial setback for the company's Alzheimer's candiate simufilam. Read more here.

Cassava Sciences' troubled development of Alzheimer's disease candidate simufilam looks like it may have finally reached the end. The Austin, Texas-based biotech revealed that simufilam failed its first phase 3 test in mild-to-moderate Alzheimer's and a second study has now been halted, leading to an 84% drop in its share price.

Cassava Sciences has revealed the late-stage clinical failure of controversial Alzheimer’s drug simulfilam. The company had pledged to share the results whether “good, bad or ambiguous.”

Cassava Sciences announced Monday that the drug, simufilam, did not significantly reduce cognitive decline in people with mild to moderate Alzheimer’s disease in the trial.