ACI-7104 was generally safe, triggered an immune response against its target
Written by Andrea Lobo | Sept. 28, 2026
- The experimental vaccine ACI-7104 targets early Parkinson’s disease by aiming to reduce toxic alpha-synuclein clumps in the brain.
- Initial Phase 2 trial results showed the vaccine was safe and successfully triggered a strong immune response.
- The study will advance into Part 2 to gather further clinical proof-of-concept data and monitor symptom progression.
ACI-7104, AC Immune’s experimental vaccine for early Parkinson’s disease, was generally safe and triggered an immune response against aggregated alpha-synuclein, according to results from the first part of a Phase 2 trial.
The findings from the VacSYn study (NCT06015841) included 34 participants, 25 who received ACI-7104 and nine who received a placebo. The company said the first part of the study met all primary goals, including those related to safety, tolerability, and immunogenicity, or the ability to generate an antibody response to the vaccine’s target.
“The results from the complete data set at week-100 in Part 1 are encouraging, with all primary endpoints met, strong immunogenicity demonstrated, and a 100% response rate,” Martin Zügel, MD, AC Immune’s interim CEO, said in a company press release.
The VacSYn trial continues in Part 1 and is advancing toward the initiation of Part 2. The final design of the second part of the study will be submitted to the U.S. Food and Drug Administration for review, with meetings expected early in 2027. The second part aims to generate clinical proof-of-concept data and to monitor the progression of Parkinson’s symptoms, as well as digital, imaging, and fluid biomarkers.
“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,” Zügel added.
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