AC Immune SA (NASDAQ:ACIU) on Thursday released interim safety and efficacy results from the Phase 2 VacSYn trial of its anti-alpha-synuclein (a-syn) active immunotherapy ACI-7104.056 in early Parkinson’s disease.
The results show, for the first time, that targeting a-syn pathology with an active immunotherapy could potentially slow the rate of progression of the disease. Disease-related biomarker results, including a-syn CSF levels and neurofilament light (NfL), suggest stabilization of its pathology.
Elevated levels of NfL have been reported as a sign of ongoing neuronal damage or neurodegeneration in Parkinson’s disease; thus, stabilization suggests a potential slowing of neuronal damage.
The stabilization of disease-relevant biomarkers in the central nervous system (CNS) suggests slowing of Parkinson’s disease pathology, with potential disease modification.
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Plasma glial fibrillary acidic protein (GFAP) and dopamine transporter (DaT) SPECT imaging show trends toward disease modification.
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.
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.
Clinical measures of motor symptoms also suggest a trend for stabilization of disease in the active arm of the study.
- Total MDS-UPDRS Part III score: At week 74, the ACI-7104.056 group did not show meaningful progression in the mean total score and change from baseline of MDS-UPDRS Part III, while the placebo arm showed an increase in mean total score, as expected in normal disease progression.
- MDS-UPDRS Part III score in L-DOPA OFF state: With stratification by levodopa (L-DOPA) ON/OFF state, the difference in the change from baseline scores between the active treatment and placebo groups was further enhanced.
Interim results from weeks 50 and 76 continue to demonstrate that ACI-7105.056 is generally safe and well-tolerated.
Final data from Part 1 of the VacSYn trial are expected in mid-2026.
ACIU Price Action: AC Immune stock is up 12.43% at $3.14 at publicatoin on Thursday.
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