Proteoform-resolved neoGFAP as a diagnostic and prognostic biomarker across the TBI--MCI--AD continuum in Veterans
- 1Gryphon Bio, South San Francisco, CA, USA; Owl Therapeutics, Cambridge, MA, USA
Abstract
Service members with traumatic brain injury are at approximately two- to four-fold higher risk of Alzheimers disease or related dementias than those without such an injury, with risk increasing with injury severity. The amyloid/tau/neurodegeneration biomarker framework treats amyloid, tau, and neurodegeneration as independent axes but omits astroglial injury, despite evidence that reactive astrogliosis (indexed by glial fibrillary acidic protein, GFAP) must be elevated for cognitive decline to occur in amyloid-positive individuals. Total GFAP immunoassays aggregate intact protein with multiple calpain- and caspase-cleaved proteoforms, blurring the biological signal. We compared a calpain-cleaved GFAP neoepitope, the glial fibrillary acidic protein neoepitope (neoGFAP), against total GFAP across the full traumatic-brain-injury-mild-cognitive-impairment-Alzheimers-disease continuum in Veterans using a two-stage plasma-to-cerebrospinal-fluid biomarker approach. A plasma triage gate combining phosphorylated tau 217 and amyloid beta 42 was applied to 367 unique subjects; a cerebrospinal-fluid benchmarking cohort of 57 subjects (controls, chronic blast traumatic brain injury, mild cognitive impairment, and Alzheimers disease) received head-to-head neoGFAP and total GFAP measurement. In the whole benchmarking cohort, neoGFAP discriminated mild cognitive impairment plus Alzheimers disease from non-Alzheimer subjects with an area under the receiver-operating-characteristic curve of 0.81 versus 0.73 for total GFAP, a trend-level advantage that did not reach nominal significance. Within the gate-positive, amyloid-committed subset of 23 subjects, neoGFAP dominance became significant by McNemars exact test (six discordant subjects favoured neoGFAP, none the reverse). Across diagnostic contrasts, neoGFAP outperformed total GFAP for Alzheimers disease versus control and, importantly for Veterans, for mild cognitive impairment versus chronic blast-exposed Veterans without cognitive impairment. In chronic blast injury, neoGFAP was paradoxically depleted relative to controls, consistent with tissue sequestration of aggregated proteoform fragments. Unbiased proteomic profiling confirmed coordinated elevation across astrocytic, neuronal, mitochondrial, and microglial compartments. An exploratory subject-level reclassification improved accuracy from 71.1 percent using plasma alone to 79.5 percent with added cerebrospinal-fluid markers and age. In a same-cohort ProQuantum replication (n=57), CSF neoGFAP preserved its discrimination advantage over total GFAP for MCI+AD versus non-AD (AUROC 0.76 vs 0.72; cross-platform Spearman {rho}=0.84), while plasma neoGFAP achieved AUROC 0.90, comparable to pTau217 (0.92) and exceeding A{beta}42/40 (0.84). In this small sample, neoGFAP is a superior proteoform-resolved diagnostic and prognostic biomarker across the continuum and supports adding an astroglial-proteoform axis to amyloid/tau/neurodegeneration biomarker frameworks in high-risk populations.
Abbreviated summaryHaskins and colleagues report that a calpain-cleaved GFAP neoepitope (neoGFAP) outperforms total GFAP for diagnostic and prognostic classification across the traumatic-brain-injury-mild-cognitive-impairment-Alzheimers-disease continuum in Veterans, supporting the addition of an astroglial-proteoform axis to amyloid/tau/neurodegeneration biomarker frameworks in high-risk populations.
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BibTeX
@misc{haskins2026proteoformresolved,
title = {{Proteoform-resolved neoGFAP as a diagnostic and prognostic biomarker across the TBI--MCI--AD continuum in Veterans}},
author = {W. E. Haskins and K. K. Wang and G. Cai and K. Boukholda and E. Elbayoumi and R. Bajpai and D. Jackson and K. Tehas and K. Radeker and A. DeLizza and C. Popper and M. Kiendl and S. Badrnya and M. Miholits and S. Jellbauer and T. Kilbaugh and F. Okumu and A. Puccio and R. C. Gardner and G. Manley and J. B. Williamson and A. B. Waters and G. G. Li and E. R. Peskind},
howpublished = {medRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.01.26361845},
url = {https://www.medrxiv.org/content/10.64898/2026.09.01.26361845v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Proteoform-resolved neoGFAP as a diagnostic and prognostic biomarker across the TBI--MCI--AD continuum in Veterans
AU - W. E. Haskins
AU - K. K. Wang
AU - G. Cai
AU - K. Boukholda
AU - E. Elbayoumi
AU - R. Bajpai
AU - D. Jackson
AU - K. Tehas
AU - K. Radeker
AU - A. DeLizza
AU - C. Popper
AU - M. Kiendl
AU - S. Badrnya
AU - M. Miholits
AU - S. Jellbauer
AU - T. Kilbaugh
AU - F. Okumu
AU - A. Puccio
AU - R. C. Gardner
AU - G. Manley
AU - J. B. Williamson
AU - A. B. Waters
AU - G. G. Li
AU - E. R. Peskind
PY - 2026
DA - 2026/09/01
PB - medRxiv
DO - 10.64898/2026.09.01.26361845
UR - https://www.medrxiv.org/content/10.64898/2026.09.01.26361845v1
AB - Service members with traumatic brain injury are at approximately two- to four-fold higher risk of Alzheimers disease or related dementias than those without such an injury, with risk increasing with injury severity. The amyloid/tau/neurodegeneration biomarker framework treats amyloid, tau, and neurodegeneration as independent axes but omits astroglial injury, despite evidence that reactive astrogliosis (indexed by glial fibrillary acidic protein, GFAP) must be elevated for cognitive decline to occur in amyloid-positive individuals. Total GFAP immunoassays aggregate intact protein with multiple calpain- and caspase-cleaved proteoforms, blurring the biological signal. We compared a calpain-cleaved GFAP neoepitope, the glial fibrillary acidic protein neoepitope (neoGFAP), against total GFAP across the full traumatic-brain-injury-mild-cognitive-impairment-Alzheimers-disease continuum in Veterans using a two-stage plasma-to-cerebrospinal-fluid biomarker approach. A plasma triage gate combining phosphorylated tau 217 and amyloid beta 42 was applied to 367 unique subjects; a cerebrospinal-fluid benchmarking cohort of 57 subjects (controls, chronic blast traumatic brain injury, mild cognitive impairment, and Alzheimers disease) received head-to-head neoGFAP and total GFAP measurement. In the whole benchmarking cohort, neoGFAP discriminated mild cognitive impairment plus Alzheimers disease from non-Alzheimer subjects with an area under the receiver-operating-characteristic curve of 0.81 versus 0.73 for total GFAP, a trend-level advantage that did not reach nominal significance. Within the gate-positive, amyloid-committed subset of 23 subjects, neoGFAP dominance became significant by McNemars exact test (six discordant subjects favoured neoGFAP, none the reverse). Across diagnostic contrasts, neoGFAP outperformed total GFAP for Alzheimers disease versus control and, importantly for Veterans, for mild cognitive impairment versus chronic blast-exposed Veterans without cognitive impairment. In chronic blast injury, neoGFAP was paradoxically depleted relative to controls, consistent with tissue sequestration of aggregated proteoform fragments. Unbiased proteomic profiling confirmed coordinated elevation across astrocytic, neuronal, mitochondrial, and microglial compartments. An exploratory subject-level reclassification improved accuracy from 71.1 percent using plasma alone to 79.5 percent with added cerebrospinal-fluid markers and age. In a same-cohort ProQuantum replication (n=57), CSF neoGFAP preserved its discrimination advantage over total GFAP for MCI+AD versus non-AD (AUROC 0.76 vs 0.72; cross-platform Spearman {rho}=0.84), while plasma neoGFAP achieved AUROC 0.90, comparable to pTau217 (0.92) and exceeding A{beta}42/40 (0.84). In this small sample, neoGFAP is a superior proteoform-resolved diagnostic and prognostic biomarker across the continuum and supports adding an astroglial-proteoform axis to amyloid/tau/neurodegeneration biomarker frameworks in high-risk populations. Abbreviated summaryHaskins and colleagues report that a calpain-cleaved GFAP neoepitope (neoGFAP) outperforms total GFAP for diagnostic and prognostic classification across the traumatic-brain-injury-mild-cognitive-impairment-Alzheimers-disease continuum in Veterans, supporting the addition of an astroglial-proteoform axis to amyloid/tau/neurodegeneration biomarker frameworks in high-risk populations.
ER -