{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T15:51:17Z","timestamp":1791215477659,"version":"4.1.0"},"posted":{"date-parts":[[2026,10,1]]},"group-title":"Neurology","reference-count":48,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T00:00:00Z","timestamp":1790812800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/www.medrxiv.org\/about\/FAQ#license"}],"funder":[{"name":"Othair Prothena Limited, Dublin, Ireland"},{"name":"NIA","award":["R01 AG052521"],"award-info":[{"award-number":["R01 AG052521"]}]},{"name":"NIA","award":["R01 AG023651"],"award-info":[{"award-number":["R01 AG023651"]}]},{"name":"NIH","award":["R01 AG083874"],"award-info":[{"award-number":["R01 AG083874"]}]},{"name":"NIH","award":["U24 AG082930"],"award-info":[{"award-number":["U24 AG082930"]}]},{"name":"NIH","award":["P30 AG066468"],"award-info":[{"award-number":["P30 AG066468"]}]},{"name":"NIH","award":["RF1 AG052525"],"award-info":[{"award-number":["RF1 AG052525"]}]},{"name":"NIH","award":["R01 AG053952"],"award-info":[{"award-number":["R01 AG053952"]}]},{"name":"NIH","award":["R37 AG023651"],"award-info":[{"award-number":["R37 AG023651"]}]},{"name":"NIH","award":["RF1 AG025516"],"award-info":[{"award-number":["RF1 AG025516"]}]},{"name":"NIH","award":["R01 AG073267"],"award-info":[{"award-number":["R01 AG073267"]}]},{"name":"NIH","award":["R01 AG075336"],"award-info":[{"award-number":["R01 AG075336"]}]},{"name":"NIH","award":["R01 AG072641"],"award-info":[{"award-number":["R01 AG072641"]}]},{"name":"NIH","award":["P01 AG025204"],"award-info":[{"award-number":["P01 AG025204"]}]},{"name":"Department of Psychiatry, University of Pittsburgh","award":["Professional Endowment"],"award-info":[{"award-number":["Professional Endowment"]}],"id":[{"id":"https:\/\/ror.org\/01an3r305","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,10,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:sec>\n                  <jats:title>INTRODUCTION<\/jats:title>\n                  <jats:p>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.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>METHODS<\/jats:title>\n                  <jats:p>\n                    Participants underwent A\u03b2 PET imaging and plasma pTau217 measurement on up to three assay platforms across three cohorts. We then developed conversion equations using Deming regression \u2013 collectively named\n                    <jats:italic>Biomarker Convert<\/jats:italic>\n                    \u2013 and evaluated robustness using independent research cohorts. Finally, we modeled the potential impact of pTau217 screening on trial enrollment.\n                  <\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>RESULTS<\/jats:title>\n                  <jats:p>\n                    While absolute plasma pTau217 concentrations differed, the assays had similar predictive characteristics for A\u03b2 positivity (LC-MS\/MS [C\n                    <jats:sub>2<\/jats:sub>\n                    N], AUC=0.952; Janssen Simoa, AUC=0.946; Lumipulse, AUC=0.929).\n                    <jats:italic>Biomarker Convert<\/jats:italic>\n                    enabled transformation of plasma pTau217 data across assays independent of A\u03b2 PET and clinical status. Plasma pTau217 reduced A\u03b2 PET scans in the model screening paradigm by &gt;60%.\n                  <\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>DISCUSSION<\/jats:title>\n                  <jats:p>\n                    <jats:italic>Biomarker Convert<\/jats:italic>\n                    equations enable harmonization of plasma pTau217 values from immunoassay and mass spectrometry platforms, supporting direct data comparison.\n                  <\/jats:p>\n                <\/jats:sec>","DOI":"10.64898\/2026.09.28.26363900","type":"posted-content","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T19:45:17Z","timestamp":1790883917000},"source":"Crossref","is-referenced-by-count":0,"title":["Biomarker Convert: a novel approach to transform plasma pTau217 results across immunoassay and mass spectrometry analytical platforms"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-3113-5800","authenticated-orcid":false,"given":"Karen J.","family":"Quadrini","sequence":"first","affiliation":[{"name":"Prothena Biosciences Inc, Brisbane, CA 94005, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4304-2430","authenticated-orcid":false,"given":"Jiri","family":"Aubrecht","sequence":"additional","affiliation":[{"name":"Prothena Biosciences Inc, Brisbane, CA 94005, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-3258-4955","authenticated-orcid":false,"given":"Frederique","family":"Vernhes","sequence":"additional","affiliation":[{"name":"Prothena Biosciences Inc, Brisbane, CA 94005, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xuemei","family":"Zeng","sequence":"additional","affiliation":[{"name":"Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA"},{"name":"Biofluid Biomarker Laboratory, Western Psychiatric Hospital, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA"},{"name":"Alzheimer\u2019s Disease Research Center, University of Pittsburgh, Pittsburgh, PA 15213, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9500-9355","authenticated-orcid":false,"given":"Ann D.","family":"Johnson","sequence":"additional","affiliation":[{"name":"Prothena Biosciences Inc, Brisbane, CA 94005, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9978-1374","authenticated-orcid":false,"given":"Beth E.","family":"Snitz","sequence":"additional","affiliation":[{"name":"Alzheimer\u2019s Disease Research Center, University of Pittsburgh, Pittsburgh, PA 15213, USA"},{"name":"Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, 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