The first Phase III trial evaluating Acadia Pharmaceuticals’ oral 5-HT2A receptor blocker, pimavanserin, failed to meet its primary antipsychotic efficacy endpoint in the treatment of Parkinson’s disease psychosis (PDP). The firm lost 70.25% of its value. It closed yesterday at $5.85 and opened trading today at $1.74.
The trial did, however, meet its secondary endpoint of motoric tolerability, as measured using the Unified Parkinson’s Disease Rating Scale. Acadia and Biovail, its North American partner for the drug, said a second Phase III PDP trial with pimavanserin will be allowed to continue while data from this failed late-stage study are analyzed further. The companies did admit they were disappointed with the results, although Biovail CEO, Bill Wells, points out that “such setbacks are not uncommon in the industry.”
The reported placebo-controlled study included 298 patients with PDP who were treated with one of two doses of oral pimavanserin in addition to their existing anti-Parkinson’s therapy. The primary endpoint was antipsychotic efficacy as measured using the hallucinations and delusions domains of the Scale for the Assessment of Positive Symptoms.
Acadia is developing pimavanserin as a treatment for psychosis associated with a range of neurological disorders including schizophrenia and Alzheimer’s disease. In 2007 the company reported positive results from a Phase II trial evaluating pimavanserin in combination with either risperidone or haloperidol.
Under terms of its agreement with Biovail, Acadia will continue to manage the ongoing Phase III trials for PDP. Biovail will lead other development, manufacturing, and commercialization efforts for pimavanserin, including activities directed at ADP and other potential indications.