AC Immune Reports Positive Interim Results From Phase 2 Trial of  Active Immunotherapy in Early Parkinson’s Disease

AC Immune SA recently announced positive interim safety and immunogenicity data from the Phase 2 VacSYn clinical trial evaluating ACI-7104.056, its wholly owned anti-alpha-synuclein (a-syn) active immunotherapy candidate, for the treatment of patients with early Parkinson’s disease (PD).

Dr. Andrea Pfeifer, CEO of AC Immune SA, said “We are encouraged by these initial Phase 2 safety and immunogenicity data on our ACI-7104.056 active immunotherapy being studied in early Parkinson’s disease. The level of immunogenicity after only 3 months of treatment as well as the continued positive safety profile, reinforces the best-in-class characteristics of our clinically validated anti-a-syn active immunotherapy for the treatment of Parkinson’s disease. We look forward to sharing further updates in H1 2025 including the decision to expand into Part 2 of the VacSYn study. As a leader in active immunotherapies for neurodegenerative diseases with two FDA Fast Track designated candidates, an important recognition of their promise, we are delighted with these initial VacSYn data. They further support the approach of using active immunotherapies to target the hallmark pathological proteins of neurodegenerative diseases, such as a-synuclein in Parkinson’s disease, before irreversible damage occurs.”

VacSYn is an adaptive, placebo-controlled, and biomarker-based Phase 2 study in patients with early PD, consisting of two parts with a seamless transition. Part 1 includes initial analyses from over 30 patients randomized to receive ACI-7104.56 or placebo at a ratio of 3:1. To date, no clinically relevant safety issues have been reported other than transient injection site reactions (49%) and headaches (18%).

Interim results show positive antibody responses were effectively induced against the target antigen at week 6 after 2 immunizations and were strongly boostable. Treatment with ACI-7104.056 induced an increase in anti-a-syn antibodies on average 16-fold higher than the placebo background level after three immunizations.

Based on further interim results to be reported in H1 2025 including pharmacodynamic data, AC Immune may decide to initiate Part 2 of VacSYn with up to 150 patients. Patients from Part 2 will also be evaluated for progression of motor and non-motor symptoms of the disease, as well as digital, imaging, and fluid biomarkers. The aim is to establish early proof-of-concept and identification of disease-specific biomarkers for rapid transition into a pivotal study.

ACI-7104.056 is an optimized formulation of its clinically validated anti-a-syn predecessor active immunotherapy which generated a target-specific antibody response against pathological oligomeric a-syn to inhibit spreading and downstream neurodegeneration in early Parkinson’s disease. The accumulation of alpha-synuclein protein aggregates has been shown to cause inflammatory stress in cells and contribute to the degeneration of neurons in the brain. It has been known to play a key role in the development of neurodegenerative diseases such as Parkinson’s Disease. Previous clinical studies showed the predecessor candidate produced a strong and boostable antibody response with evidence of target engagement and a signal of clinical efficacy.

AC Immune SA is a clinical-stage biopharmaceutical company and a global leader in precision prevention for neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and NeuroOrphan indications driven by misfolded proteins. The Company’s two clinically validated technology platforms, SupraAntigen and Morphomer, fuel its broad and diversified pipeline of first- and best-in-class assets, which currently features sixteen therapeutic and diagnostic programs, including five in Phase 2 development and one in Phase 3. AC Immune has a strong track record of securing strategic partnerships with leading global pharmaceutical companies, resulting in substantial non-dilutive funding to advance its proprietary programs and >$4.5 billion in potential milestone payments plus royalties.