AC Immune reports breakthrough preliminary data for experimental ALS diagnostic tracer

AC Immune (NASDAQ:ACIU) announced positive preliminary Phase 1 clinical data for its experimental brain imaging agent, ACI-19626, expanding its diagnostic reach into amyotrophic lateral sclerosis (ALS).

The data, presented at the 2026 TDP43 Summit in Madison, Wisconsin, demonstrate that the first-in-class transactivation response element DNA-binding protein 43 (TDP-43) positron emission tomography (PET) tracer showed significantly higher uptake in key brain regions of ALS patients compared to healthy control subjects.

TDP-43 protein aggregates are recognized as a core pathological hallmark in roughly 95% of ALS cases and roughly half of all frontotemporal dementia (FTD) cases.

Until now, the lack of sensitive, non-invasive biomarkers capable of visualizing these aggregates in living patients has been a primary bottleneck for clinical diagnosis and targeted drug development.

The latest findings build on earlier data from the ongoing trial, which demonstrated similar elevated tracer retention in disease-relevant subcortical and cortical brain regions among individuals with genetically defined FTD.

From a clinical safety and pharmacokinetics standpoint, ACI-19626 was reported to be safe and well-tolerated.

The tracer exhibited rapid brain uptake and washout properties alongside a favorable radiation dosimetry profile that falls within internationally accepted limits.

Management stated that these operational dynamics support its utility as a viable, repeated human brain imaging tool.

The clinical-stage biopharmaceutical firm expects the imaging agent to play a dual role in precision medicine, functioning as both an early-stage diagnostic biomarker for TDP-43 proteinopathies and an objective measurement tool to evaluate target engagement for upcoming neurodegenerative therapeutics.