ACADIA has announced that it has begun ENHANCE-1, a phase 3 study designed to evaluate pimavanserin as an adjunctive treatment for schizophrenia. Specifically, the trial will help researchers understand if it can be used in patients who have shown an inadequate response to a current antipsychotic therapy.

Pimavanserin is a selective serotonin inverse agonist that targets 5-HT2A receptors. These receptors are believed to play an important role in schizophrenia. Pimavanserin (34 mg) has already been approved to treat hallucinations and delusions associated with Parkinson’s disease psychosis.

“We believe pimavanserin, through its highly selective mechanism of action, could provide an important new option for adjunctive treatment of schizophrenia and improve clinical outcomes by both augmenting the efficacy of currently used antipsychotics and lessening the undesirable side effects associated with polypharmacy,” said Serge Stankovic, MD, MSPH, ACADIA’s executive vice president and head of research and development.

ENHANCE-1 is a 6-week, randomized, double-blind, placebo-controlled, multicenter outpatient study designed to examine the efficacy and safety of the adjunctive use of pimavanserin. About 380 patients will be randomized to receive pimavanserin or the placebo orally, once per day, in addition to their ongoing antipsychotic treatment. The primary endpoint is the change from baseline to week 6 on the Positive and Negative Symptom Scale total score.

The most common adverse effects associated with pimavanserin are bloating, confusion, nausea, and rapid weight gain.