AC Immune Reports Positive Week 100 Phase 2 Data for ACI-7104 in Parkinson's; Shares Rise

AC Immune SA (ACIU) reported positive Week-100 results from Part 1 of its Phase 2 VacSYn trial evaluating vaccine candidate ACI-7104 in patients with early-stage Parkinson's disease on September 23, 2026. The company's shares rose on the announcement. The Swiss biotech said the vaccine demonstrated a favorable safety and immunogenicity profile over the 100-week period. ACI-7104 targets alpha-synuclein, the protein implicated in Parkinson's pathology. AC Immune did not disclose detailed efficacy figures in the initial release. The VacSYn trial is designed to assess whether the vaccine can slow disease progression in early-stage patients, a population with limited treatment options beyond symptomatic therapy.