Commercially Available Plasma p-tau217 Biomarker Immunoassay for Alzheimer Disease as Accurate as CSF Biomarker Testing According to New Study

Results of a study published in JAMA Neurology demonstrated the high diagnostic accuracy and consistency of a commercially available phosphorylated tau at threonine 217 (p-tau217) test (ALZpath, Carlsbad, CA) in identifying abnormal amyloid beta (Aβ) and tau concentrations associated with Alzheimer disease (AD) pathology. Findings from this large observational cohort study conducted over 8 years showed the p-tau217 test results to be consistent with results obtained from traditional cerebrospinal fluid (CSF) biomarker tests for detecting AD pathology.

The study included 768 participants across 3 cohorts:

• Translational Biomarkers of Aging and Dementia (TRIAD) in Canada (n=268)
• Wisconsin Registry for Alzheimer’s Prevention (WRAP) in the United States (n=323)
• Saint Pau Initiative on Neurodegeneration (SPIN) in Spain (n=195)

The population included people with and without cognitive impairment, and participants were grouped by Aβ and tau status based on CSF biomarkers (Aβ42/Aβ40 ratio, p-tau immunoassays), Aβ PET, and tau PET. Researchers applied a 3-range strategy to identify a lower and upper reference point corresponding to CSF and PET measures to rule out or rule in AD. Participants in the intermediate range required confirmatory testing.

• In all 3 cohorts, the p-tau217 blood biomarker test showed high accuracy in identifying elevated Aβ (area under the curve [AUC], 0.92 to 0.96; 95% CI, 0.89 to 0.99) as well as tau pathology (AUC, 0.93 to 0.97; 95% CI, 0.84 to 0.99).
• The accuracy of the p-tau217 blood biomarker test was consistent with that of CSF biomarker assays in analyzing abnormal PET signal.
• Use of a 3range approach for Aβ positivity based on plasma p-tau217 biomarker testing reduced the need for confirmatory imaging testing by approximately 80%.

“ALZpath's pTau217 test can help healthcare providers determine the presence of amyloid plaques in the brain - a hallmark of Alzheimer's disease,” said Dr. Andreas Jeromin, Chief Scientific Officer of ALZpath. “This diagnostic capability offers increasingly vital aid in medical management and treatment decisions for Alzheimer's, especially as new disease-modifying treatments become more accessible.”