Safety and Tolerability Profile
Consistent with previous studies, pimavanserin was safe and well tolerated in the -020 Study. The most common adverse events were urinary tract infection (11.7% PBO vs. 13.5% PIM) and falls (8.5% PBO vs. 10.6% PIM). Adverse events were generally characterized as mild to moderate in nature. The only serious adverse events that occurred in more than one patient were urinary tract infection (1-PBO vs. 3-PIM) and psychotic disorder (0-PBO vs. 2-PIM). Over ninety percent of the patients who completed the clinical phase of this trial elected to roll over into the ongoing open-label safety extension study. Patients were only eligible to participate in the extension study if the treating investigator also deemed them to be likely to benefit from continued treatment with pimavanserin.
About the Trial Design
The pivotal Phase III trial, referred to as the -020 Study, was a multi-center, double-blind, placebo-controlled study designed to evaluate the efficacy, tolerability and safety of pimavanserin as a treatment for patients with Parkinson’s disease psychosis. A total of 199 patients were enrolled in the study and randomized on a one-to-one basis to receive either 40 mg 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 -020 Study was antipsychotic efficacy as measured using the “SAPS–PD” scale, which consists of nine items from the hallucinations and delusions domains of the Scale for the Assessment of Positive Symptoms, or SAPS. These nine items have been shown to be particularly relevant to the expression of psychotic symptoms in patients with Parkinson’s disease and to have high inter-rater reliability for assessment of severity. Motoric tolerability was a key secondary endpoint in the study and was measured using Parts II and III of the Unified Parkinson’s Disease Rating Scale, or UPDRS.