AC Immune Presents First In vivo Images of Brain TDP-43 Pathology from Phase 1 Trial of PET tracer ACI-19626, at AD/PDTM 2026

AC Immune Presents First In vivo Images of Brain TDP-43 Pathology from Phase 1 Trial of PET tracer ACI-19626, at AD/PD^TM 2026

• Initial data indicates significantly higher tracer uptake in patients with genetically defined FTD
• Good safety and tolerability and suitable PK profile for human brain imaging
• Potentially enables precision medicine across multiple neurodegenerative diseases
  
  

Lausanne, Switzerland, March 19, 2026 -- AC Immune SA (NASDAQ: ACIU), a clinical-stage biopharmaceutical company pioneering precision therapeutics for neurodegenerative diseases, today announced the presentation of Phase 1 data including the first in vivo images of TDP-43 pathology in the human brain, detected using its first-in-class positron emission tomography (PET) tracer ACI-19626, at the International Conference on Alzheimer’s and Parkinson’s Disease (AD/PD™ 2026).

Initial data from the Phase 1 trial support ACI-19626’s potential to detect pathological TDP-43 in the brains of patients with TDP-43 proteinopathies, enabling a precision medicine approach to multiple neurodegenerative diseases.

Specifically, PET scans with ACI-19626 showed that tracer uptake was significantly higher in key regions of the brain in patients with frontotemporal dementia (FTD) due to mutated C9orf72 than in the brains of healthy subjects. As presented, regions with higher tracer uptake included subcortical and cortical regions of the brain where TDP-43 pathology is expected based on post-mortem neuropathology studies. ACI-19626 showed good safety and tolerability, a dosimetry profile within accepted limits, and rapid brain uptake and washout, indicating a pharmacokinetic (PK) profile suitable for human brain imaging and potentially pharmacodynamic analysis of therapeutics targeting TDP-43 pathology.

Dr. Andrea Pfeifer, CEO of AC Immune SA, commented: “These first-in-human data presented at AD/PD™ are very encouraging and indicate that ACI-19626 could have an important role in early diagnosis of multiple neurogenerative diseases, with a clear path to precision medicine. This underlines the potential of the AC Immune pipeline, based on our SupraAntigen^® and Morphomer^® technology platforms, for precision prevention of multiple conditions, encompassing diagnostics, active immunotherapies and small molecules for intracellular targeting. We are looking forward to final data from Part 1 of this study, expected in H1 2026, and have started Part 2 in other patient populations to further define its potential role in this new treatment paradigm.”

TDP-43 is the main component in inclusions found in the brains of people with FTD, amyotrophic lateral sclerosis (ALS) and limbic-predominant age-related TDP-43 encephalopathy (LATE), as well as a co-pathology in Alzheimer’s disease (AD) and Parkinson’s disease (PD). These conditions share many of the same clinical signs and symptoms, making differential diagnosis a difficult and lengthy process in the absence of reliable biomarkers.

The Phase 1, first-in-human trial (Clinicaltrials.gov: NCT06891716) is in two parts. Part 1 is investigating ACI-19626 in healthy volunteers and patients with genetic FTD and is expected to be completed in H1 2026. The Part 2 expansion may include up to 30 patients with FTD, ALS or LATE. Exploration of ACI-19626 binding in additional patient populations including ALS is ongoing.

About AC Immune SA 

AC Immune SA is a clinical-stage biopharmaceutical company and a global leader in precision prevention for neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and NeuroOrphan indications driven by misfolded proteins. The Company’s two clinically validated technology platforms, SupraAntigen® and Morphomer®, fuel its pipeline of first- and best-in-class assets, which currently features a range of therapeutic and diagnostic programs, including candidates in Phase 2 and Phase 3 development. AC Immune has a strong track record of securing strategic partnerships with leading global pharmaceutical companies, resulting in substantial non-dilutive funding to advance its proprietary programs and >$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.

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• 20260319__ACIU ADPD TDP-43-Final

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