LAUSANNE, Switzerland — December 11, 2025 — AC Immune SA has released positive interim Phase 2 data for its investigational active immunotherapy ACI-7104.056, demonstrating unprecedented potential to slow progression in early Parkinson’s disease, with 100% immunogenicity, favorable safety, and biomarker trends indicating disease stabilization according to the company’s announcement.
Science Significance
The interim findings represent a scientific milestone in neurodegeneration research, as this is the first human evidence that directly targeting alpha-synuclein (a-syn) pathology with an active immunotherapy may slow Parkinson’s progression. Biomarker stabilization — including CSF a-syn, neurofilament light (NfL), GFAP, and DaT SPECT imaging signals — suggests modified disease trajectory, while robust antibody responses in serum and CSF confirm successful blood-brain barrier penetration, a critical hurdle in neurodegenerative therapy. The data reinforce the growing importance of precision immunotherapies in conditions driven by misfolded proteins and highlight the potential for disease-modifying treatment, a long-sought goal in Parkinson’s research.
Regulatory Significance
From a regulatory perspective, the results deliver a compelling argument for accelerated development pathways, as AC Immune plans to engage regulatory authorities to define a strategy for registration-oriented development. With no clinically relevant safety issues and consistent biomarker-based signals of efficacy, the therapy aligns with current regulatory priorities emphasizing biologically validated endpoints, patient-centered outcomes, and innovative trial design. Successful continuation to later-stage studies could position ACI-7104.056 as one of the first active immunotherapies targeting a-syn to enter a regulatory review process with disease-modifying claims, a rare and significant milestone.
Business Significance
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For AC Immune, the promising interim data strengthens its standing as a leader in precision neurodegenerative therapeutics and enhances the commercial value of its SupraAntigen® and Morphomer® platforms. With multiple assets in clinical development and more than $4.5B in potential milestone partnerships, the company is well-positioned for future investment and strategic alliances. The ability of ACI-7104.056 to meet all immunogenicity, pharmacodynamic, and clinical targets increases investor confidence in the platform’s scalability and potential for first-in-class and best-in-class therapies. Positive momentum from this Phase 2 program could accelerate collaborations, expand pipeline diversification, and strengthen AC Immune’s market footprint in the competitive neurodegeneration space.
Patients’ Significance
For millions living with Parkinson’s disease, the early signals of stabilized motor symptoms, slowed biomarker decline, and robust immune engagement offer a new horizon of hope. Current therapies primarily treat symptoms rather than underlying pathology. ACI-7104.056 could become one of the first treatments designed to modify disease progression, reducing long-term disability and improving quality of life. Importantly, the favorable safety and tolerability profile — with mostly mild, transient adverse events such as injection-site reactions, headache, and fatigue — supports the therapy’s potential for chronic, long-term use in early-stage patients.
Policy Significance
At a policy level, the findings underscore the necessity for continued investment in neurodegenerative research, particularly therapies targeting misfolded protein pathology. Policymakers may view this as a pivotal moment to expand funding for precision immunotherapy, accelerate frameworks for adaptive trial designs, and strengthen international collaboration in Parkinson’s research. As population aging increases the global burden of neurodegenerative diseases, the emergence of potential disease-modifying interventions may influence future reimbursement models, regulatory incentives, and healthcare resource planning.
The interim Phase 2 results for ACI-7104.056 mark a significant milestone for AC Immune and the broader neurodegenerative research community, offering compelling early evidence that active immunotherapy targeting a-syn may slow Parkinson’s disease progression. As the company prepares for regulatory engagement and final Part 1 data in 2026, the global scientific, clinical, and patient communities will be watching closely to determine whether this promising therapy can usher in a new era of disease-modifying treatments for Parkinson’s disease.
Source: AC Immune SA press release
