AC Immune (NASDAQ:ACIU) surged 25% on Thursday after announcing promising interim Phase 2 findings for its experimental Parkinson’s disease treatment, indicating the therapy may help slow the underlying progression of the disorder.
The company’s investigational therapy, ACI-7104.056 — an active immunotherapy targeting alpha-synuclein — produced encouraging outcomes in the VacSYn study involving patients in the early stages of Parkinson’s. According to AC Immune, the treatment hit all immunogenicity targets, achieving a 100% responder rate, while early signals suggested a potential disease-modifying effect.
Biomarker data reinforced the clinical observations: levels of alpha-synuclein and neurofilament light chain in cerebrospinal fluid remained stable among individuals receiving the therapy, whereas these markers worsened in the placebo arm. Measures of motor function likewise indicated stabilization in treated patients compared with declines seen in those untreated.
“The remarkable consistency of the trends observed across multiple disease-related biomarkers and on clinical assessments in the treatment arm are very promising,” said Werner Poewe, emeritus Professor of Neurology at Innsbruck Medical University. “If further substantiated the current data would have major implications for future PD therapy. For the first time, we are seeing signals that targeting the underlying pathology of Parkinson’s with active immunotherapy could slow disease progression.”
Safety results were positive as well, with no significant safety concerns identified. Common side effects included temporary injection-site reactions, headaches, and fatigue.
Following the strong interim readout, AC Immune said it intends to consult regulators about whether development of the treatment could be accelerated toward potential approval. Final results from Part 1 of the VacSYn trial are expected in mid-2026.