AC Immune SA announced positive interim results from its Phase 2 VacSYn clinical trial evaluating ACI-7104.056, an anti-alpha-synuclein active immunotherapy for early Parkinson's disease. The data revealed robust antibody responses and a favorable safety profile after six months of treatment, potentially marking a significant advancement in disease-modifying approaches for this neurodegenerative condition.
The Switzerland-based biopharmaceutical company reported that its wholly-owned immunotherapy candidate induced anti-alpha-synuclein antibody levels averaging more than 20-fold higher than placebo after four immunizations. Importantly, each additional immunization further amplified the antibody response, demonstrating the treatment's "boostability" and potential for sustained therapeutic effect.
"We continue to be encouraged by the data emerging from the Phase 2 VacSYn trial," said Dr. Andrea Pfeifer, CEO of AC Immune SA. "These additional interim safety and immunogenicity data after 6 months of treatment underscore the good safety profile and reinforce the best-in-class characteristics of ACI-7104.056 for the treatment of Parkinson's disease."
Trial Design and Safety Profile
The VacSYn study employs an adaptive, placebo-controlled design with over 30 patients in Part 1, randomized to receive either ACI-7104.056 or placebo at a 3:1 ratio. The interim safety analysis revealed no serious adverse events related to the study drug. The most common side effects were mild and transient injection site reactions and headaches, generally of mild severity.
Interim immunogenicity results demonstrated that positive antibody responses were effectively induced against the target antigen at week 6 after just two immunizations. The antibody response continued to strengthen with subsequent doses, suggesting a durable immunological effect.
Targeting Alpha-Synuclein Pathology
ACI-7104.056 represents an optimized formulation of a clinically validated predecessor immunotherapy. The treatment works by generating a target-specific antibody response against pathological oligomeric alpha-synuclein, a protein whose aggregation plays a central role in Parkinson's disease pathogenesis.
Alpha-synuclein protein aggregates have been shown to cause inflammatory stress in cells and contribute to neuronal degeneration in the brain. By targeting these aggregates, ACI-7104.056 aims to inhibit disease progression at its molecular source.
Previous clinical studies with the predecessor candidate demonstrated a strong and boostable antibody response with evidence of target engagement and signals of clinical efficacy, providing a foundation for the current Phase 2 program.
Future Development Plans
Based on further interim results expected later in 2025, including pharmacodynamic and biomarker data, AC Immune may initiate Part 2 of the VacSYn trial with up to 150 additional patients. This expanded cohort would evaluate multiple exploratory endpoints, including:
- Progression of motor and non-motor symptoms
- Digital biomarkers
- Imaging biomarkers
- Fluid biomarkers
The ultimate goal is to establish early proof-of-concept and identify disease-specific biomarkers that could facilitate a rapid transition into pivotal studies.
Implications for Parkinson's Treatment
Parkinson's disease affects approximately 10 million people worldwide, with limited treatment options primarily focused on symptom management rather than disease modification. Current therapies like levodopa address dopamine deficiency but do not target the underlying pathological processes.
If successful, ACI-7104.056 could represent a paradigm shift in Parkinson's treatment by directly targeting the protein aggregation believed to drive disease progression. This approach aligns with similar strategies being explored in other neurodegenerative conditions, including Alzheimer's disease.
The immunotherapy approach offers several potential advantages, including the possibility of less frequent dosing compared to small molecule drugs and the specificity of targeting pathological protein forms while sparing normal physiological proteins.
About AC Immune
AC Immune SA (NASDAQ: ACIU) is a clinical-stage biopharmaceutical company specializing in precision therapeutics for neurodegenerative diseases. The company leverages its proprietary technology platforms, SupraAntigen® and Morphomer®, to develop treatments for conditions including Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders driven by misfolded proteins.
The company has established strategic partnerships with leading pharmaceutical companies, securing substantial non-dilutive funding and potential milestone payments exceeding $4.5 billion plus royalties to advance its development programs.
With ACI-7104.056 showing promising interim results, AC Immune continues to position itself at the forefront of innovative approaches to treating neurodegenerative diseases. The company plans to share additional updates on the VacSYn trial later in 2025.
