AC Immune reported interim biomarker data from its phase II Vacsyn program showing changes consistent with target engagement in early Parkinson’s disease. The company said cerebrospinal fluid alpha‑synuclein, neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP) and DaT‑SPECT imaging trended in ways that could signal disease modification. Management said the biomarker package supports discussions with regulators to potentially accelerate development. The data come from ACI‑7104 active immunotherapy cohorts and include safety and pharmacodynamic readouts presented at a major neurology meeting. Observers called the signals encouraging but cautioned that biomarker shifts do not substitute for clinical endpoints; AC Immune plans further analyses and regulatory engagement to define a path toward confirmatory trials.