Abstract Details

Title Breaking Barriers in Early Alzheimer's Disease Diagnosis: The Power of the In Vitro Diagnostic Elecsys pT181p Immunoassay in a Population Reflective of Real-world Clinical Practice

Topic Aging, Dementia, and Behavioral Neurology

Presentation(s) P4 - Poster Session 4 (8:00 AM-9:00 AM)

Poster/Presentation
Number 12-010

Objective This study validated a plasma tau phosphorylated at threonine 181 (pTau181p) cutoff using the Elecsys® Phospho-Tau (181P) assay (Roche Diagnostics) to rule out amyloid pathology in a diverse real-world cohort

Background Early diagnosis of Alzheimer’s disease (AD) is critical for optimizing management, outcomes, and quality of life. Current disease-modifying therapies target amyloid-β (Aβ), making amyloid pathology identification vital for diagnosis and treatment. Confirmatory tests like positron emission tomography (PET) and cerebrospinal fluid (CSF) are costly, invasive, and limited in availability. Blood-based biomarkers (BBBMs) show promise for improving access to early AD diagnosis. Validating BBBM performance in clinically representative populations is essential for practical application.

Design/Methods

This prospective, multi-center study included 18 sites across the US, Europe, and Australia. Patients aged 55–80 with cognitive complaints or memory impairment of unknown causes were enrolled. Clinical stages included subjective cognitive decline (SCD), mild cognitive impairment (MCI), or mild dementia. Plasma pTau181p levels were measured using the Elecsys pT181p immunoassay. The pre-established cutoff of 0.934 pg/mL was validated against amyloid-PET and CSF pTau181/Aβ42 ratio results. Clinical performance metrics included the area under the curve (AUC), negative predictive value (NPV), and positive predictive value (PPV).

Results Of 787 patients, 650 had amyloid-PET results (43.8% male, mean age 69.3 years). Amyloid prevalence was 22.5% via PET and 28.0% via CSF. The AUC for pTau181p relative to amyloid-PET and CSF pTau181/Aβ42 ratio was 0.854 and 0.818, respectively. The NPV for amyloid-PET was 93.8%, independent of comorbidities, demonstrating strong rule-out performance.

Conclusions The pT181p immunoassay showed high performance in ruling out amyloid pathology across diverse clinical settings. Its utility could enhance access to early AD diagnosis, improving patient care and health outcomes while reducing economic burden.

Authors/Disclosures
Chris Stamatkin, PhD (Roche) PRESENTER	Dr. Stamatkin has received personal compensation for serving as an employee of Roche.
Sayuri Hortsch, PhD	Dr. Hortsch has received personal compensation for serving as an employee of Roche Diagnostics GmbH.
David Caley, MRes	Mr. Caley has nothing to disclose.
Patrick Menzel, PhD	Dr. Menzel has nothing to disclose.
Christopher C. Rowe, MD, PhD	Prof. Rowe has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Novo Nordisk. Prof. Rowe has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Prothena. Prof. Rowe has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Eisai Australia. Prof. Rowe has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Lilly Australia. Prof. Rowe has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche Diagnostics. Prof. Rowe has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Prof. Rowe has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Novo Nordisk. Prof. Rowe has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Roche Diagnostics. Prof. Rowe has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Johnson and Johnson. The institution of Prof. Rowe has received research support from Enigma. The institution of Prof. Rowe has received research support from Australian Dementia Network Ltd. The institution of Prof. Rowe has received research support from National Health and Medical Research Council. The institution of Prof. Rowe has received research support from Florey Institute of Neuroscience.
Mark Rapp, MD (Berman Clinical)	Dr. Rapp has nothing to disclose.
Dag Aarsland, MD (King's College London)	Dr. Aarsland has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Roche Diagnostics.
Anna Burke, MD	Dr. Burke has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Lilly. Dr. Burke has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Eisai. Dr. Burke has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Alector. An immediate family member of Dr. Burke has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for Lilly.
Clara Quijano Rubio, PhD	Dr. Quijano Rubio has received personal compensation for serving as an employee of Roche Diagnostics International.

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