AC Immune announces additional data from Phase 2 study of VacSYn clinical trial

AC Immune (ACIU) announced additional interim safety and positive immunogenicity data from the Phase 2 VacSYn clinical trial evaluating ACI-7104.056, its wholly owned anti-alpha-synuclein, or a-syn, active immunotherapy candidate, for the treatment of patients with early Parkinson’s disease, or PD. VacSYn is an adaptive, placebo-controlled, and biomarker-based Phase 2 study in patients with early PD, consisting of two parts with a seamless transition. Part 1 includes initial analyses from over 30 patients randomized to receive ACI-7104.056 or placebo at a ratio of 3:1. To date, in the blinded, pooled active and placebo groups, no serious adverse event considered related to the study drug has been reported. The most common adverse events are mild and transient injection site reactions and headaches, generally of mild severity. Interim results show positive antibody responses were effectively induced against the target antigen at week 6 after 2 immunizations and were further boosted by each additional immunization. Treatment with ACI-7104.056 induced an increase in anti-a-syn antibodies on average over 20-fold higher than the placebo background level after four immunizations. Based on further interim results to be reported later in 2025 including pharmacodynamic and biomarker data, AC Immune may decide to initiate Part 2 of VacSYn with up to 150 patients. Further exploratory endpoints for patients in Part 2 will include the evaluation of the progression of motor and non-motor symptoms of the disease, as well as digital, imaging, and fluid biomarkers. The aim is to establish early proof-of-concept and identification of disease-specific biomarkers for rapid transition into a pivotal study.