Study summary
An antibody against alpha-synuclein missed its main goal but is going to a larger trial
What was tested
Prasinezumab, an antibody that binds alpha-synuclein, the protein that clumps in Parkinson's, given monthly by infusion to people with early disease.
What they found
- The trial did not meet its main goal.
- Pre-planned secondary analyses suggested slower movement decline in some groups.
- Five-year follow-up without a placebo group was modelled as about two years of delay, a weaker kind of evidence.
- A 900-person phase 3 trial started in November 2025.
What it means
Not proven. The phase 3 trial is the real test of whether targeting alpha-synuclein slows the disease.
Last reviewed 2026-11-14 by the Find a Trial editorial team.
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