Shares of Acadia Pharmaceuticals (ACAD - Get Report)  rocketed more than 60% on Monday after the company announced it stopped early a phase 3 trial of its dementia-related psychosis treatment, pimavanserin, on better-than-expected results. 

Shares of Acadia surged 62.34%, or $14.84 a share, at $38.64 on the Nasdaq Stock Market after the San Diego-based biotechnology company announced that its pimavanserin trial was stopped early "for efficacy" -- meaning the results were far better than anticipated.

The company said pimavanserin achieved "robust statistical superiority," with longer time to relapse of psychosis with pimavanserin compared with a placebo.

$ACAD ACADIA Pharmaceuticals Announces Pivotal Phase 3 HARMONY Trial Stopped Early for Positive Efficacy as Pimavanserin Meets the Primary Endpoint in Patients with Dementia-Related Psychosishttps://t.co/EnS3nJ1gZa

— Joe (@GantosJ) September 9, 2019

Acadia plans to meet with the Food and Drug Administration regarding a supplemental new drug application submission in 2020. The FDA previously granted the company "Breakthrough Therapy Designation" for pimavanserin. 

Pimavanserin has the potential to be the first FDA-approved drug for the treatment of dementia-related psychosis, of which some 1.2 million U.S. patients been diagnosed with, according to the company.

Investors had the opposite response to Acadia shares in July after the company said pimavanserin had failed to meet key benchmarks in a different late-phase trial related to symptoms of schizophrenia.