The journal of applied laboratory medicine · 2025
Analytical Validation and Performance of a Blood-Based P-tau217 Diagnostic Test for Alzheimer Disease.
СтатьяВалидационное исследованиеНазвание и аннотация: Перевод пока не подготовлен
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Abel Adam, Chambers Antonio, Fill Jeff, Reiske Heinz, Lu Ming, Morris Amanda, Faya Paul, Beck Rose C, Pontecorvo Michael J, Collins Emily C, Schade Andrew E, Mintun Mark A, Hodsdon Michael E
Аннотация
BACKGROUND: Blood-based biomarkers, especially P-tau217, have been gaining interest as diagnostic tools to measure Alzheimer disease (AD) pathology.
METHODS: We developed a plasma P-tau217 chemiluminescent immunoassay using 4G10E2 and IBA493 as antibodies, a synthetic tau peptide as calibrator, and the Quanterix SP-X imager. Analytical validation performed in a College of American Pathologists-accredited CLIA laboratory involved multiple kit lots, operators, timepoints, and imagers. Florbetapir positron emission tomography was used to quantify amyloid for clinical validation.
RESULTS: Precision across 80 runs was ≤20% CV using 23 patient-derived samples ranging from 0.09 U/mL to 3.35 U/mL. No significant lot-to-lot differences were observed. There was no interference from purified tau (2N4R) or lipemia, but hemolysis greater than 2 + was not acceptable. Functional analytical sensitivity (lower limit of quantitation) was 0.08 U/mL. Linearity studies support the use of a standard 1:2 plasma dilution. Samples demonstrated stability at 7 freeze/thaw cycles, with room temperature and refrigerated stability established for up to 72 hours. The final analytical measurement range was 0.08 to 2.81 U/mL. The calibration curve maintained ≤20% CV for raw signal intensity and 80% to 120% relative error for back-fitted concentration using a log-log power regression. Initial clinical assessment using plasma samples from 1091 individuals screened in TRAILBLAZER-ALZ 2 demonstrated an area under the curve of 91.6% (95% CI 0.90-0.94) with brain amyloid as the comparator. Positive and negative predictive value was >90% and >85%, respectively.
CONCLUSIONS: Through analytical validation, this assay demonstrated robust performance across multiple lots, operators, and instruments and could be used as a tool for diagnosing AD.
METHODS: We developed a plasma P-tau217 chemiluminescent immunoassay using 4G10E2 and IBA493 as antibodies, a synthetic tau peptide as calibrator, and the Quanterix SP-X imager. Analytical validation performed in a College of American Pathologists-accredited CLIA laboratory involved multiple kit lots, operators, timepoints, and imagers. Florbetapir positron emission tomography was used to quantify amyloid for clinical validation.
RESULTS: Precision across 80 runs was ≤20% CV using 23 patient-derived samples ranging from 0.09 U/mL to 3.35 U/mL. No significant lot-to-lot differences were observed. There was no interference from purified tau (2N4R) or lipemia, but hemolysis greater than 2 + was not acceptable. Functional analytical sensitivity (lower limit of quantitation) was 0.08 U/mL. Linearity studies support the use of a standard 1:2 plasma dilution. Samples demonstrated stability at 7 freeze/thaw cycles, with room temperature and refrigerated stability established for up to 72 hours. The final analytical measurement range was 0.08 to 2.81 U/mL. The calibration curve maintained ≤20% CV for raw signal intensity and 80% to 120% relative error for back-fitted concentration using a log-log power regression. Initial clinical assessment using plasma samples from 1091 individuals screened in TRAILBLAZER-ALZ 2 demonstrated an area under the curve of 91.6% (95% CI 0.90-0.94) with brain amyloid as the comparator. Positive and negative predictive value was >90% and >85%, respectively.
CONCLUSIONS: Through analytical validation, this assay demonstrated robust performance across multiple lots, operators, and instruments and could be used as a tool for diagnosing AD.