Tool converts plasma pTau217 values across testing platforms
Assays predicted amyloid-beta positivity with AUCs of 0.929 to 0.952, while simulated pTau217 screening cut amyloid PET scans by over 60%.
medRxiv
In human participants evaluated across three study cohorts, researchers tested a method to translate plasma phosphorylated tau 217 (pTau217) results between different laboratory platforms. Participants received amyloid-beta PET imaging and blood pTau217 tests on up to three analytical systems: LC-MS/MS (C2N), Janssen Simoa, and Lumipulse. Using Deming regression, the team developed equations called Biomarker Convert and assessed their performance in independent cohorts.
According to the preprint, absolute pTau217 concentrations varied across assays, yet each platform showed similar predictive accuracy for amyloid-beta positivity, with AUCs of 0.952 for LC-MS/MS, 0.946 for Janssen Simoa, and 0.929 for Lumipulse. The Biomarker Convert equations harmonized pTau217 values across systems independent of clinical status or amyloid-beta PET results. When applied in a trial screening model, plasma pTau217 prescreening reduced required amyloid-beta PET scans by more than 60%.
Why it matters
Harmonizing plasma pTau217 readouts across different testing platforms allows researchers to directly compare data across clinical trials and observational studies of age-related neurodegenerative disease.
Caveats
The findings were reported in a preprint and have not yet undergone peer review. The reported reduction in PET imaging was derived from a screening model rather than a prospective clinical trial.
The paper
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Xuemei Zeng, Ann D. Johnson, Beth Ellen Snitz, Ann D. Cohen, Ryan E. Tooker, Mary Ellen Quiceno, Brian M Campbell, Thomas K. Karikari,Prothena (United States)
medRxiv · 1 Oct 2026 · Preprint, not peer-reviewed