Sage Therapeutics craters 64% after failing a key trial for its depression drug

• Shares of Sage Therapeutics, a Cambridge-based pharmaceutical company, cratered almost 64% on Thursday morning.
• The crash came after the drugmaker - which focuses on brain disorders - reported disappointing study results for a key depression treatment.
• The trial showed that patients who took the drug didn't see more relief compared with participants taking a placebo over a two-week period.
• Watch Sage Therapeutics trade live on Markets Insider.

Shares of Cambridge-based drugmaker Sage Therapeutics tanked almost 64% on Thursday morning after the company posted disappointing results for a key drug trial.

The $7.7 billion pharmaceutical company said Thursday that patients taking a new antidepressant for major depressive disorder in a late-stage trial called "Mountain" didn't show more relief than participants receiving a placebo over a two-week period.

"This study did not meet the primary endpoint," Sage CEO Jeff Jonas said in a statement. "With that, the data are supportive of the activity of SAGE-217 in given the statistical significance at the majority of timepoints, and in relevant populations."

Sage's stock shed more than $4.5 billion in market value as the results represent the key drug's first major setback. The experimental depression treatment, dubbed Sage 217, posted promising results in clinical trials earlier this year.

The treatment works differently from most major depression drugs on the market. Sage 217 targets a different brain system, which is supposed to make the drug work faster and last longer.

"Notwithstanding the finding on the primary endpoint, the drug displays good activity on most measures," Jonas said.

He added: "We've gathered new data on SAGE-217, data we believe support our hypothesis that SAGE-217 has a unique profile with the potential for rapid and robust onset with durable effect."