Plasma pTau‐217 and N‐terminal tau (NTA) enhance sensitivity to identify tau PET positivity in amyloid‐β positive individuals
Marcel S. Woo, Cécile Tissot, Juan Lantero‐Rodriguez, Anniina Snellman, Joseph Therriault, Nesrine Rahmouni, Arthur C. Macedo, Stijn Servaes, Yi‐Ting Wang, Jaime Fernández Arias, Seyyed Ali Hosseini, Mira Chamoun, Firoza Z Lussier, Andréa L. Benedet, Nicholas J. Ashton, Thomas K. Karikari, Gallen Triana‐Baltzer, Hartmuth C. Kolb, Jenna Stevenson, Christina Mayer, Eliane Kobayashi, Gassan Massarweh, Manuel A. Friese, Tharick A. Pascoal, Serge Gauthier, Henrik Zetterberg, Kaj Blennow, Pedro Rosa‐Neto
Abstract
Abstract INTRODUCTION We set out to identify tau PET‐positive (A+T+) individuals among amyloid‐beta (Aβ) positive participants using plasma biomarkers. METHODS In this cross‐sectional study we assessed 234 participants across the AD continuum who were evaluated by amyloid PET with [ 18 F]AZD4694 and tau‐PET with [ 18 F]MK6240 and measured plasma levels of total tau, pTau‐181, pTau‐217, pTau‐231, and N‐terminal tau (NTA‐tau). We evaluated the performances of plasma biomarkers to predict tau positivity in Aβ+ individuals. RESULTS Highest associations with tau positivity in Aβ+ individuals were found for plasma pTau‐217 (AUC [CI 95% ] = 0.89 [0.82, 0.96]) and NTA‐tau (AUC [CI 95% ] = 0.88 [0.91, 0.95]). Combining pTau‐217 and NTA‐tau resulted in the strongest agreement (Cohen's Kappa = 0.74, CI 95% = 0.57/0.90, sensitivity = 92%, specificity = 81%) with PET for classifying tau positivity. DISCUSSION The potential for identifying tau accumulation in later Braak stages will be useful for patient stratification and prognostication in treatment trials and in clinical practice. Highlights We found that in a cohort without pre‐selection pTau‐181, pTau‐217, and NTA‐tau showed the highest association with tau PET positivity. We found that in Aβ+ individuals pTau‐217 and NTA‐tau showed the highest association with tau PET positivity. Combining pTau‐217 and NTA‐tau resulted in the strongest agreement with the tau PET‐based classification.