AC Immune SA (NASDAQ: ACIU) on Wednesday shared week-100 safety and immunogenicity results from Part 1 of its Phase 2 VacSYn clinical trial evaluating ACI-7104 in patients with early-stage Parkinson's disease.
"We will now refine our approach to the next development steps in the program and discuss our plans with regulators before embarking on an expanded Phase 2 trial designed to provide evidence of clinical activity as the basis for entry into Phase 3," said Martin Zügel, Interim CEO of AC Immune.
Phase 2 Trial Design And Patient Cohort
The VacSYn clinical study divides its evaluation process into two parts. Part 1 aims to demonstrate safety, tolerability, and immunogenicity, while Part 2 seeks to provide clinical activity evidence to serve as the foundation for a Phase 3 decision.
The newly reported Part 1 dataset includes results from all 34 randomized patients enrolled in the trial, comprising 25 patients who received ACI-7104 and nine control participants who received a placebo.
Primary Endpoints And CSF Penetration Results
The trial successfully met all primary endpoints for Part 1, confirming that ACI-7104 proved generally safe, well-tolerated, and strongly immunogenic.
Following three immunizations, 100% of treated patients successfully developed antibodies against the immunizing alpha-synuclein target antigen PD01.
Furthermore, the therapy demonstrated clear antibody reactivity against aggregated species of alpha-synuclein, while researchers observed robust antibody penetration into the cerebrospinal fluid across all treated patients.
Exploratory Biomarker Signals And Regulatory Next Steps
Although Part 1 did not specifically evaluate formal biomarker or clinical outcomes, additional exploratory analyses monitored clinical measures of disease activity and specific cerebrospinal fluid biomarkers, such as total alpha-synuclein and Neurofilament Light chain.
Researchers observed a distinct signal for total alpha-synuclein in the cerebrospinal fluid, offering preliminary evidence consistent with target engagement.
Exploratory correlation analyses also identified positive trends suggesting an association between immunogenicity antibody levels and disease activity measures.
The VacSYn trial continues with a two-year extension in Part 1 as the company advances toward initiating the Part 2 expansion.
Management is consolidating the final Part 2 trial design to submit to the FDA for review, with regulatory meetings expected in early 2027.
ACIU Price Action: AC Immune shares were up 1.08% at $2.75 at the time of publication on Wednesday, according to market data.
