This Phase 2b randomized trial tested prasinezumab in individuals with early-stage Parkinson's disease. Participants were between 50 and 85 years old and had been diagnosed within three years. They received either intravenous prasinezumab every four weeks or a placebo. The study took place across 110 centers in Europe and North America. A total of 586 people were enrolled and randomly assigned to groups.
The main goal was to see if the drug could delay motor progression, defined as a five-point increase in a specific movement score. The results showed a non-significant delay in motor progression with prasinezumab versus placebo. The hazard ratio was 0.84 with a p-value of 0.066. The median time to confirmed motor progression was 61.1 weeks in the prasinezumab group versus 49.7 weeks in the placebo group.
Safety data showed similar rates of serious adverse events between groups. Twelve percent of participants in the prasinezumab group experienced serious adverse events, matching the placebo group exactly. The primary endpoint was not met. Readers should understand that this early trial did not confirm clinical activity of prasinezumab in early-stage Parkinson's disease based on prespecified exploratory evidence.