An update on immune-based alpha-synuclein trials in Parkinson's disease.

Parkinson's disease (PD) is a prevalent, chronic neurodegenerative disorder characterised by the progressive loss of dopaminergic neurons in the substantia nigra and other brain regions. The aggregation of alpha-synuclein (α-syn) into Lewy bodies and neurites is a key pathological feature associated with PD and its progression. Many therapeutic studies aim to target these aggregated forms of α-syn to potentially slow down or stop disease progression in PD. This review provides a comprehensive analysis of recent clinical trials involving vaccines and monoclonal antibodies targeting α-syn. Specifically, UB-312, AFFITOPE PD01A, PD03A and ACI-7104.056 are designed to provoke an immune response against α-syn (active immunisation), while Prasinezumab and Cinpanemab, MEDI1341 and Lu AF82422 focus on directly targeting α-syn aggregates (passive immunisation). Despite some promising results, challenges such as variable efficacy and trial discontinuations persist. Future research must address these challenges to advance disease-modifying therapies for PD around this therapeutic target.