AC Immune reported interim biomarker data from a mid‑stage Parkinson’s study suggesting the company’s immunotherapy may slow disease progression, and said it will seek regulatory feedback to potentially accelerate an approval path. The firm emphasized encouraging early biological signals but acknowledged that clinical‑endpoint interpretation remains uncertain. Investors reacted to the mixed clinical clarity: the data underpin continued development but highlight the need for clearer functional outcomes in later trials. AC Immune’s readouts underscore the wider challenge of translating biomarker shifts into definitive clinical benefit in neurodegeneration.