SPEAR UltraDetect™ BD-pTau 217 Assay Kit

BD-pTau 217 for Enhanced Alzheimer’s Disease Specificity

Plasma phosphorylated tau at threonine 217 (pTau 217) is among the most effective blood biomarkers for Alzheimer’s disease (AD), demonstrating strong concordance with amyloid PET imaging and cerebrospinal fluid (CSF) biomarkers.

However, emerging evidence indicates that circulating pTau 217 is not exclusively derived from the central nervous system (CNS). Peripheral conditions, heterogeneous comorbidities, and pre-analytical variables may influence measured plasma pTau 217 levels — potentially confounding interpretation in screening and early-stage research.

Brain-derived pTau 217 (BD-pTau 217) represents a CNS-specific subset of circulating pTau 217. By targeting low–molecular-weight CNS-derived tau species, BD-pTau 217 provides enhanced specificity for Alzheimer’s pathology while preserving the advantages of blood-based testing.

For studies where peripheral influences may confound total plasma pTau 217 measurements, BD-pTau 217 offers refined CNS specificity without compromising detectability.

100% Quantifiability in Healthy Individuals

BD-pTau 217 is present at ultra-low concentrations in plasma, particularly in asymptomatic and early-stage individuals, making reliable detection analytically challenging.

The SPEAR UltraDetect™ BD-pTau 217 assay uniquely delivers:

• 100% quantifiability across all samples of healthy individuals
• Functional LLoQ of 25 fg/mL

Robust Amyloid Discrimination

Evaluated in PET-confirmed cohorts from the Global Alzheimer’s Platform (GAP), plasma BD-pTau 217 levels measured using SPEAR UltraDetect™ demonstrate:

• 4.56X fold difference between amyloid-negative (A–) and amyloid-positive (A+) groups
• AUC > 0.94 for amyloid classification
• 100% quantifiability across all samples
• Average intra-plate CV of 5.7%

Minimal Sample Input. Maximum Performance.

The homogeneous, wash-free assay requires only 1 µL of diluted plasma, enabling high-throughput workflows, longitudinal and multi-site studies, and micro-sampling approaches such as dried plasma spot (DPS) collection — without compromising sensitivity, precision, or quantifiability.