AC Immune Speeds Toward a Potential Parkinson’s Breakthrough with FDA Fast Track Status

Key Points

• AC Immune received FDA Fast Track designation for ACI-7104, its investigational active immunotherapy for early Parkinson’s disease.
• The company also received FDA clearance for its investigational new drug application, allowing the Phase 2 VacSYn trial to expand to U.S. sites.
• Full 100-week data from the first part of the Phase 2 study are expected in the second half of 2026.

AC Immune (Nasdaq: ACIU) has received FDA Fast Track designation for ACI-7104, an investigational anti-alpha-synuclein immunotherapy being developed for early Parkinson’s disease. The regulatory update supports the company’s plans to expand its ongoing Phase 2 VacSYn trial and marks an important step in the development of a potential disease-modifying treatment for Parkinson’s.

ACI-7104 targets alpha-synuclein in Parkinson’s disease

ACI-7104 is designed to stimulate the immune system to create antibodies against aggregated alpha-synuclein, a protein linked to Parkinson’s disease and the gradual loss of nerve cells. The treatment aims to target abnormal protein aggregates that may contribute to disease progression.

Unlike therapies that primarily address Parkinson’s symptoms, ACI-7104 is being studied as a potential disease-modifying treatment. The program remains in clinical development, and it has not yet been shown to slow disease progression or received regulatory approval.

FDA Fast Track status may support a more efficient development path

The FDA grants Fast Track designation to programs intended to treat serious conditions with unmet medical need. The designation can provide more frequent interactions with the FDA and may allow a company to submit portions of a future marketing application on a rolling basis, if regulatory requirements are met.

For AC Immune, the designation follows FDA clearance of the company’s IND application. That clearance enables the company to expand the ongoing Phase 2 VacSYn study of ACI-7104 into U.S. clinical sites.

Phase 2 interim data show immune response and favorable safety profile

AC Immune previously reported interim 76-week data from Part 1 of the Phase 2 VacSYn study. The company said ACI-7104 was safe and generally well tolerated, with no clinically relevant safety issues observed at the time of the analysis.

The company also reported a 100% immunogenicity response rate. Earlier data showed that the optimized ACI-7104.056 formulation generated anti-alpha-synuclein antibody levels averaging 16 times higher than placebo after three immunizations. These results demonstrate an immune response, but they do not establish clinical benefit or disease modification.

Full Phase 2 results expected in the second half of 2026

AC Immune expects to report final 100-week data from Part 1 of the Phase 2 VacSYn trial in the second half of 2026. The company also plans to extend the study for two additional years to further evaluate long-term safety and potential efficacy.

For ACIU investors, the full data release will be the program’s next major catalyst. Key areas to watch include long-term safety, antibody durability, biomarker results, and any evidence that ACI-7104 affects Parkinson’s symptoms or underlying disease progression.