Acadia to stop trials of antipsychotic drug after it fails schizophrenia study

(Reuters) -Acadia Pharmaceuticals said on Monday it does not plan to conduct further clinical trials of its antipsychotic drug, pimavanserin, after it failed to improve negative symptoms of schizophrenia in a late-stage study.

Shares of the California-based company fell 16% in extended trading.

The decision comes after two failed attempts to secure regulatory approval for the expanded use of pimavanserin in the treatment of psychosis related to dementia and Alzheimer's disease in 2021 and 2022, respectively.

In the current study that involved 454 adult patients, pimavanserin did not outperform a placebo in reducing negative symptoms of schizophrenia, including poor socialization and lack of motivation, Acadia said.

Schizophrenia is a chronic mental disorder that causes distortion in thoughts, hallucinations and feelings of fright and paranoia, and affects less than 1% of the U.S. population, according to the American Psychiatric Association.

In 2016, pimavanserin, sold under the brand name Nuplazid, became the first drug approved in the United States to treat hallucinations and delusions associated with psychosis experienced by some people with Parkinson's disease.

Nuplazid contributed $522.7 million in revenue last year, making up nearly 72% of the company's total sales.

Treatments approved in the U.S. for schizophrenia include antipsychotic generic drugs such as risperidone and olanzapine.

(Reporting by Mariam Sunny in Bengaluru; Editing by Shweta Agarwal)