AC Immune announced positive interim Phase 2 VacSYn trial results for ACI-7104.056, an active immunotherapy targeting alpha-synuclein in early Parkinson's disease, on December 11, 2025123.
Interim data from 34 patients (12-18 months treatment) showed 100% antibody responder rate, serum/CSF antibody titers over 500x higher than placebo, and strong blood-brain barrier penetration1.
Biomarkers stabilized in treatment arm:
CSF alpha-synuclein stabilized (vs decrease in placebo, p=0.018), NfL stable (vs increase in placebo), trends in GFAP and DaT SPECT123.
Motor symptoms (MDS-UPDRS Part III) showed no progression in treatment group over 74 weeks vs expected decline in placebo13.
Therapy well-tolerated with no serious adverse events; common issues were transient injection site reactions3.
Company plans regulatory discussions for accelerated path; final Phase 2 data expected mid-2026124.
Experts like Dr. Werner Poewe note promising signals of slowed progression, supporting further development23.
Sources:
1. https://marketchameleon.com/articles/b/2025/12/11/ac-immune-phase-2-data-parkinsons-disease-aciu
2. https://biotuesdays.com/2025/12/11/ac-immune-reports-positive-interim-data-of-a-syn-active-immunotherapy-in-early-pd/
3. https://www.biopharmadive.com/news/ac-immune-parksinsons-drug-data-alpha-synuclein/807688/
4. https://pharmaphorum.com/news/ac-immune-says-parkinsons-drug-slows-progression