Pimavanserin Effective in Pivotal Parkinson’s Disease Psychosis Trial

Acadia Pharmaceuticals announced successful top-line results from its pivotal Phase 3 trial evaluating the efficacy, tolerability and safety of pimavanserin in patients with Parkinson’s disease psychosis (PDP). Pimavanserin is a non-dopaminergic product that selectively blocks serotonin 5-HT_2A receptors.

The trial was a multi-center, double-blind, placebo-controlled study. A total of 199 patients were enrolled in the study and randomized on a one-to-one basis to receive either 40mg of pimavanserin or placebo once-daily for six weeks, following a two-week screening period including brief psycho-social therapy. Patients also received stable doses of their existing anti-Parkinson’s therapy throughout the study.

The primary endpoint of the trial was antipsychotic efficacy as measured using the SAPS-PD, a 9-item scale adapted from the hallucinations and delusions domains of the Scale for the Assessment of Positive Symptoms, by comparing the mean change from baseline to Day 43 for pimavanserin vs. placebo. SAPS-PD assessments were performed by blinded, independent centralized raters. The pimavanserin arm demonstrated a 5.79 point improvement in psychosis at Day 43 compared to a 2.73 point improvement for placebo, representing a highly significant and clinically meaningful treatment difference of 3.06 points on SAPS-PD (P=0.001).

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