ACI-7104.056 - (VacSYn)

September 23, 2026: AC Immune SA (NASDAQ: ACIU) reported positive week-100 Part 1 Phase 2 VacSYn data for ACI-7104 in early-stage Parkinson’s disease. In the randomized, double-blind, placebo-controlled study (34 patients; 25 ACI-7104, 9 placebo), all Part 1 primary endpoints were met: safety, tolerability, and immunogenicity.

ACI-7104 was generally safe and well tolerated, with 100% of treated patients developing antibodies against the immunizing alpha-synuclein target antigen PD01 after three immunizations. The company also reported antibody reactivity against aggregated alpha-synuclein species and antibody penetration into cerebrospinal fluid in all patients. Although Part 1 was not designed to assess biomarkers or clinical outcomes, exploratory analyses showed a signal for total alpha-synuclein in CSF consistent with target engagement, and trends suggesting an association between antibody levels and disease activity measures.

The VacSYn study continues in a two-year Part 1 extension and is advancing toward Part 2, which is intended to provide evidence of clinical activity to support a Phase 3 decision. AC Immune said the final Part 2 design will be submitted to FDA for review, with meetings expected in early 2027.