# AC Immune Positive Interim Phase 2 Data on ACI-7104.056 Support Potential Slowing of Progression of Parkinson’s Disease Canonical URL: https://biopharmsignal.com/news/ACIU/ac-immune-positive-interim-phase-2-data-on-aci-7104-056-support-potential-slowin-ca30a27d Ticker: ACIU Company: AC Immune Source: AC Immune Published: 2025-12-11 12:00 EST ## Summary The results show, for the first time, that targeting a-syn pathology with an active immunotherapy could potentially slow the rate of progression of PD.... ## Article Body AC Immune Positive Interim Phase 2 Data on ACI-7104.056 Support Potential Slowing of Progression of Parkinson’s Disease Results show, for the first time, that targeting underlying a-syn pathology with an active immunotherapy could slow the rate of progression of Parkinson’s disease Clear safety profile with no clinically relevant safety issues reported Targets met for immunogenicity (100% responder rate), pharmacodynamic effect, target engagement and clinical assessments Underlines potential and importance of active immunotherapies in precision medicine for neurodegenerative diseases AC Immune to host webcast and conference call today at 9:00am ET / 15:00 CET details below Lausanne, Switzerland, December 11, 2025 -- AC Immune SA (NASDAQ: ACIU), a clinical-stage biopharmaceutical company pioneering precision therapeutics for neurodegenerative diseases, today announced positive interim safety and efficacy results from the Phase 2 VacSYn trial of its wholly-owned anti-alpha-synuclein (a-syn) active immunotherapy ACI-7104.056 in early Parkinson’s disease (PD). The results show, for the first time, that targeting a-syn pathology with an active immunotherapy could potentially slow the rate of progression of PD. Disease-related biomarker results, including a-syn CSF levels and neurofilament light (NfL), suggest stabilization of PD pathology. Plasma glial fibrillary acidic protein (GFAP) and dopamine transporter (DaT) SPECT imaging show trends toward disease modification. In addition, total scores on Part III of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) are suggestive of a trend for stabilization. Dr. Andrea Pfeifer, CEO of AC Immune SA, commented: “The interim Phase 2 data shows the potential of our ACI-7104.056 active immunotherapy to slow the progression of Parkinson’s disease and hold the promise of a tremendous step forward for millions of patients. The consistent signs of efficacy, combined with the continuing strong safety record, underline ACI-7104.056’s potential to transform PD treatment and are a strong basis for accelerating development. We will discuss ACI-7104.056 with the regulators to establish a clinical development plan towards registration.” Werner Poewe, MD, emeritus Professor of Neurology at Innsbruck Medical University and a leading expert in Parkinson’s disease , commented: "The remarkable consistency of the trends observed across multiple disease-related biomarkers and on clinical assessments in the treatment arm are very promising. Importantly, clinical and biomarker outcomes provide signals that the immunological response elicited by ACI-7104 may be associated with beneficial effects on PD progression. Overall, these findings are highly encouraging and fully support further development of the program. If further substantiated the current data would have major implications for future PD therapy. For the first time, we are seeing signals that targeting the underlying pathology of Parkinson’s with active immunotherapy could slow disease progression.” Interim results VacSYn (ClinicalTrials.gov: NCT06015841 ) is an adaptive, placebo-controlled, and biomarker-based Phase 2 study in patients with early PD, consisting of two parts. Part 1 includes 34 patients randomized 3:1 to receive ACI-7104.056 or placebo, respectively. All participants in this interim analysis have been treated for at least 12 months (i.e. 48 weeks), with 20 participants treated for up to 18 months (i.e. 74 weeks). Interim results showed all target criteria for immunogenicity were met, including: Antibody titers in serum : ACI-7104.056 induced a robust antibody response against the immunizing a-syn target antigen with a 100% responder rate. At week 76, two weeks after the sixth immunization, antibody titers in serum were over 500-fold higher than in the placebo group. Antibody responses to both the immunizing and the native a-syn peptide were boosted after each dose from the second to the sixth immunization, while the placebo group did not show any detectable signal. Antibody titers in the cerebrospinal fluid (CSF) : Titers against the immunizing a-syn target antigen increased with successive immunizations, showing ACI-7104.056 generates antibodies that cross the blood-brain barrier. As seen in serum, average IgG antibody levels in CSF were over 500-fold higher than in the placebo group. Correlation between serum and CSF antibody titers: changes from baseline in antibody concentrations in CSF were statistically significantly correlated to changes from baseline in titers in serum (Spearman correlation at week 24 = 0.92, p$4.5 billion in potential milestone payments plus royalties. SupraAntigen® is a registered trademark of AC Immune SA in the following territories: AU, EU, CH, GB, JP, RU, SG and USA. Morphomer® is a registered trademark of AC Immune SA in CA, CN, CH, EU, GB, JP, KR, NO, RU and SG. The information on our website and any other websites referenced herein is expressly not incorporated by reference into, and does not constitute a part of, this press release. For further information, please contact: Forward looking statements This press release contains statements that constitute “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Forward-looking statements are statements other than historical fact and may include statements that address future operating, financial or business performance or AC Immune’s strategies or expectations. In some cases, you can identify these statements by forward-looking words such as “may,” “might,” “will,” “should,” “expects,” “plans,” “anticipates,” “believes,” “estimates,” “predicts,” “projects,” “potential,” “outlook” or “continue,” and other comparable terminology. Forward-looking statements are based on management’s current expectations and beliefs and involve significant risks and uncertainties that could cause actual results, developments and business decisions to differ materially from those contemplated by these statements. These risks and uncertainties include those described under the captions “Item 3. Key Information – Risk Factors” and “Item 5. Operating and Financial Review and Prospects” in AC Immune’s Annual Report on Form 20-F and other filings with the Securities and Exchange Commission. Forward-looking statements speak only as of the date they are made, and AC Immune does not undertake any obligation to update them in light of new information, future developments or otherwise, except as may be required under applicable law. 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