Acadia Pharmaceuticals’ treatment for Parkinson’s disease-related psychosis failed a Phase 3 trial that was studying use of the drug for schizophrenia patients who haven’t fully responded to existing therapies.
The company announced the trial failure Monday after market close. Acadia (NASDAQ: ACAD) shares dropped about 4 percent on the news in after-hours trading, falling from just shy of $26 each to about $22 apiece.
Acadia’s study of its drug pimavanserin enrolled 396 people with moderate-to-severe psychotic symptoms that had shown some improvement with their current treatment but continued experiencing symptoms (what’s known as an “inadequate” response). Those existing treatments had to be one of nine antipsychotic drugs, such as Bristol-Myers Squibb’s (NYSE: BMY) aripiprazole (Abilify).
Half received pimavanserin, which they took in addition to their current treatment, and the rest got a placebo. The six-week study didn’t find statistical significance in the improvements of schizophrenia patients’ symptoms as measured on a scale of the severity of those symptoms.
About 88 percent of people taking pimavanserin and 96 percent of those taking the placebo completed the study, Acadia said, with 2.5 percent of those taking pimavanserin discontinuing the trial due to adverse events. None of the patients taking the placebo discontinued due to adverse events. Acadia said the drug was generally well-tolerated; at least 5 percent of patients in the pimavanserin group reported side effects that included headache, sleepiness, and insomnia.
The company said it would continue with its Phase 2 clinical trial evaluating the drug in schizophrenia patients who exhibit what’s known as “negative” symptoms, such as a lack of responsiveness or apparent disinterest in social interaction. Results are anticipated around year’s end.
Acadia is also studying pimavanserin as a treatment for dementia-related psychosis and major depressive disorder.