Biomarker Convert: a novel approach to transform plasma pTau217 results across immunoassay and mass spectrometry analytical platforms

Abstract INTRODUCTION We report the development and validation of a novel computational tool to cross-convert plasma pTau217 results from different assays to facilitate recruitment for therapeutic trials and observational studies. METHODS Participants underwent Aβ PET imaging and plasma pTau217 measurement on up to three assay platforms across three cohorts. We then developed conversion equations using Deming regression – collectively named Biomarker Convert – and evaluated robustness using independent research cohorts. Finally, we modeled the potential impact of pTau217 screening on trial enrollment. RESULTS While absolute plasma pTau217 concentrations differed, the assays had similar predictive characteristics for Aβ positivity (LC-MS/MS [C 2 N], AUC=0.952; Janssen Simoa, AUC=0.946; Lumipulse, AUC=0.929). Biomarker Convert enabled transformation of plasma pTau217 data across assays independent of Aβ PET and clinical status. Plasma pTau217 reduced Aβ PET scans in the model screening paradigm by >60%. DISCUSSION Biomarker Convert equations enable harmonization of plasma pTau217 values from immunoassay and mass spectrometry platforms, supporting direct data comparison.