AC Immune has reported positive week-100 results from part 1 of its phase 2 VacSyn trial evaluating ACI-7104 in early-stage Parkinson’s disease. The data cover all 34 patients enrolled, including 25 on ACI-7104 and nine on placebo.
The company said all primary endpoints were met, with ACI-7104 shown to be generally safe and well tolerated. Strong immunogenicity was demonstrated, with a 100% antibody response rate after three immunisations.
Part 1 was designed to assess safety, tolerability and immunogenicity rather than clinical outcomes, but exploratory analyses indicated signals for target engagement. Clear antibody penetration into the cerebrospinal fluid was observed in all patients.
A signal was detected for total a-syn in the cerebrospinal fluid, providing preliminary evidence consistent with target engagement. Trends were also seen linking antibody levels with disease activity measures.
“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,” said Martin Zügel, Interim CEO, AC Immune. “This program is one of our strongest active immunotherapies, with ACI-7104-induced antibodies demonstrating preferential binding to aggregated a-syn species.”
“We are pleased to have observed strong and boostable immune responses, with significant antibody penetration into the CSF and signals for target engagement,” explained Günther Staffler, Executive Vice President, Development, AC Immune. “Together with the favorable safety profile through week-100, and exploratory correlations between antibody titers and disease activity measures, we are confident that these results provide a strong foundation for the continued development of ACI-7104 into Part 2.”
The trial continues in its two-year extension phase and is advancing toward initiation of part 2. AC Immune plans to discuss the final design with the FDA in early 2027.
