AC Immune Presents New Phase 1 Data Indicating Higher Uptake of TDP-43 PET Tracer ACI-19626 in Patients with ALS

AC Immune Presents New Phase 1 Data Indicating Higher Uptake of TDP-43 PET Tracer ACI-19626 in Patients with ALS

Presentation at 2026 TDP43 Summit shows ACI-19626 detects TDP-43 pathology in patients with amyotrophic lateral sclerosis (ALS)

Previously reported data also showed detection of TDP-43 in patients with genetically defined frontotemporal dementia (FTD)

Underlines potential for precision medicine enabling early diagnosis and intervention in multiple neurodegenerative diseases

Lausanne, Switzerland, May 22, 2026 -- AC Immune SA (NASDAQ: ACIU), a clinical-stage biopharmaceutical company pioneering precision therapeutics for neurodegenerative diseases, today announced the presentation of new preliminary data from a Phase 1 trial of its first-in-class TDP-43 positron emission tomography (PET) tracer ACI-19626 showing increased uptake in the brains of patients with amyotrophic lateral sclerosis (ALS).

The results presented at the 2026 TDP43 Summit in Madison, Wisconsin, demonstrate that PET scans with ACI-19626 showed tracer uptake significantly higher in key regions of the brain in patients with ALS compared to healthy controls. Specifically, tracer uptake was higher in the brain stem (* see image below) and precentral gyrus, where TDP-43 pathology is expected to accumulate based on post-mortem neuropathology studies and on clinical symptoms. Previously reported data showed significantly higher tracer uptake in disease-relevant subcortical and cortical regions in patients with genetic frontotemporal dementia (FTD).

ACI-19626 continues to show 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 data in ALS patients provide further evidence of ACI-19626’s potential to detect pathological TDP-43 in the brains of patients with TDP-43 proteinopathies. Early diagnosis is essential for early intervention, and the data generated so far on ACI-19626 further underline the promise of the AC Immune pipeline and our technology to enable a precision medicine approach to multiple neurodegenerative diseases.”

The ongoing Phase 1, first-in-human trial ( Clinicaltrials.gov : NCT06891716 ) has two parts. Part 1 investigating ACI-19626 in healthy volunteers and patients with genetic FTD is completed. The Part 2 expansion has started and may include up to 30 patients with FTD, ALS or LATE.

The 2026 Summit Advancing TDP43 Biomarkers is hosted by the University of Wisconsin–Madison and the Wisconsin Alzheimer’s Disease Research Center’s (ADRC) Consortium for Clarity in ADRD Research Through Imaging (CLARiTI).

* Post-hoc analysis from expert third-party independent of the study (for informational purposes only and does not constitute official, final data)

About TDP-43

TDP-43 is the main component in inclusions found in the brains of people with FTD, 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.

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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Forward looking statements

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