Plasma p-tau217 measured by the Elecsys automated immunoassay: Prospective validation in a heterogeneous memory clinic cohort

Background Plasma phosphorylated tau at threonine 217 (p-tau217) has emerged as a leading blood-based biomarker for the diagnosis of Alzheimer's disease (AD) and can be measured using fully automated, random-access platforms. The Elecsys plasma p-tau217 assay requires further validation, particularly in heterogenous populations seen in memory clinics. Objective To validate plasma p-tau217 in comparison with p-tau181 and to evaluate its association with other soluble core 1 AD biomarkers, as well as markers of neurodegeneration and neuroinflammation. Methods Biobank data from two prospective blood-based biomarkers validation studies were analyzed. Cerebrospinal fluid (CSF) p-tau181/Aβ 42 ratio served as the reference standard for AD diagnosis. The diagnostic performance of plasma p-tau217 and p-tau181 was compared. In patients with AD, p-tau217 was further evaluated for its association with CSF (Aβ 42 /Aβ 40 ratio, p-tau181, t-tau) and plasma [APOE ε4 protein (APOE ε4p), NfL (neurofilament light chain), GFAP (glial fibrillary acidic protein)] biomarkers. Results Among 303 patients with mild cognitive impairment or mild dementia, plasma p-tau217 outperformed plasma p-tau181 (AUC 0.93 versus 0.87). By the two threshold diagnostic strategy, an upper cutoff (>0.312 pg/mL, specificity 95%) and a lower cutoff (<0.177 pg/mL, sensitivity 95%) were established, with 27% of cases falling into an indeterminate range. Plasma p-tau217 showed strong correlations with CSF Aβ 42 /Aβ 40 and p-tau181/Aβ 42 ratios, as well as with plasma GFAP, and only moderate correlations with CSF t-tau and p-tau181, and plasma NfL. Conclusions Plasma p-tau217 measured using Elecsys demonstrates good diagnostic performance and strong associations with other soluble Core 1 AD and neuroinflammation biomarkers.

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Journal
Journal of Alzheimer s Disease
Published
2026-06-16
DOI
https://doi.org/10.1177/13872877261459067
Primary Topic
Dementia and Cognitive Impairment Research
Type
article
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article

Plasma p-tau217 measured by the Elecsys automated immunoassay: Prospective validation in a heterogeneous memory clinic cohort

Emilio Franco‐Macías, Eduardo Agüera, Pedro Jesús Serrano-Castro, Gonzalo Mendoza-Vázquez et al.
Journal of Alzheimer s Disease
Dementia and Cognitive Impairment Research
article

Plasma p-tau217 measured by the Elecsys automated immunoassay: Prospective validation in a heterogeneous memory clinic cohort

Emilio Franco‐Macías, Eduardo Agüera, Pedro Jesús Serrano-Castro, Gonzalo Mendoza-Vázquez, Cristina Conde, Silvia Rodrigo‐Herrero, José Ángel Noval-Padillo, Carmen García-Navarro, Begoña Oliver‐Martos, Ernesto García‐Roldán, Carlos Arrabal-Gómez, José Enrique Arriola‐Infante, Maria-Isabel García-Sanchéz, Eva Cuartero-Rodriguez, Bartolomé Marín-Romero, Mar Iglesias-Espinosa, Beatriz Espejo-Martínez, Ángela Almodóvar‐Sierra, María Bernal Sánchez‐Arjona, Melisa González-Acosta, Marta Marín-Cabañas, Daniel Fatela-Cantillo, Rocío Hervás-Navidad, Cristina Serrano-Gutiérrez, Lucía Rodríguez-Jiménez, Lina Carazo-Barrios, Francisco Garzón-Maldonado, Ana María Jover, David José Romera-Morales, Ángel Martínez-Nogueras, Ismael Carrera-Muñoz, Carlota Méndez-Barrio
article en

Abstract

Background Plasma phosphorylated tau at threonine 217 (p-tau217) has emerged as a leading blood-based biomarker for the diagnosis of Alzheimer's disease (AD) and can be measured using fully automated, random-access platforms. The Elecsys plasma p-tau217 assay requires further validation, particularly in heterogenous populations seen in memory clinics. Objective To validate plasma p-tau217 in comparison with p-tau181 and to evaluate its association with other soluble core 1 AD biomarkers, as well as markers of neurodegeneration and neuroinflammation. Methods Biobank data from two prospective blood-based biomarkers validation studies were analyzed. Cerebrospinal fluid (CSF) p-tau181/Aβ 42 ratio served as the reference standard for AD diagnosis. The diagnostic performance of plasma p-tau217 and p-tau181 was compared. In patients with AD, p-tau217 was further evaluated for its association with CSF (Aβ 42 /Aβ 40 ratio, p-tau181, t-tau) and plasma [APOE ε4 protein (APOE ε4p), NfL (neurofilament light chain), GFAP (glial fibrillary acidic protein)] biomarkers. Results Among 303 patients with mild cognitive impairment or mild dementia, plasma p-tau217 outperformed plasma p-tau181 (AUC 0.93 versus 0.87). By the two threshold diagnostic strategy, an upper cutoff (>0.312 pg/mL, specificity 95%) and a lower cutoff (<0.177 pg/mL, sensitivity 95%) were established, with 27% of cases falling into an indeterminate range. Plasma p-tau217 showed strong correlations with CSF Aβ 42 /Aβ 40 and p-tau181/Aβ 42 ratios, as well as with plasma GFAP, and only moderate correlations with CSF t-tau and p-tau181, and plasma NfL. Conclusions Plasma p-tau217 measured using Elecsys demonstrates good diagnostic performance and strong associations with other soluble Core 1 AD and neuroinflammation biomarkers.

Journal of Alzheimer s Disease
Andalusian Health Service (ES), Fundación Pública Andaluza para la Gestión de la Investigación en Salud de Sevilla (ES), Hospital Regional Universitario de Málaga (ES), Instituto de Investigación Biosanitaria de Granada (ES), Hospital Universitario Virgen de las Nieves (ES), Complejo Hospitalario de Jaén (ES), Hospital Universitario Reina Sofía (ES), Hospital Juan Ramón Jiménez (ES), Victoria School of Management (CH), Neuron BioPharma (Spain) (ES), Hospital Universitario de Valme (ES), Andalusian Centre for Nanomedicine and Biotechnology (ES), Complejo Hospitalario Torrecárdenas (ES), Hospital Universitario Virgen del Rocío (ES), Hospital Clínico Universitario Virgen de la Victoria (ES), Andalusian School of Public Health (ES), Universidad de Málaga (ES)
Good health and well-being
Openalex Percentile: Top 7%
Dementia and Cognitive Impairment Research
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