. Discriminative Accuracy of Plasma Phospho-tau217 for Alzheimer Disease vs Other Neurodegenerative Disorders. JAMA. 2020 Aug 25;324(8):772-781. PubMed.

AlzBiomarker Database

Meta-Analysis

Curated Study Data

Biomarker
(Source)
Cohort
(N)
Measurement
Mean ± SD
Method;
Assay Name;
Manufacturer
Diagnostic
Criteria
NFL
(Plasma)
AD-
biomarker-pos
(121)
27.08 ± 25.2
pg/mL §
SIMOA;
Other/Not Specified;
In-house
NFL
(Plasma)
CTRL-
biomarker-neg
(224)
13.28 ± 6.75
pg/mL §
SIMOA;
Other/Not Specified;
In-house
NFL
(Plasma)
FTD-
bvFTD
(21)
31.77 ± 14.95
pg/mL §
SIMOA;
Other/Not Specified;
In-house
NFL
(Plasma)
PD
(32)
17 ± 8.45
pg/mL §
SIMOA;
Other/Not Specified;
In-house
Gelb et al., 1999
NFL
(Plasma)
PSP
(20)
27.05 ± 13.04
pg/mL §
SIMOA;
Other/Not Specified;
In-house
tau-p181
(CSF)
AD-
biomarker-pos
(121)
87.89 ± 35.86
pg/mL §
ELISA;
Innotest;
Fujirebio
tau-p181
(CSF)
CTRL-
biomarker-neg
(224)
40.5 ± 13.54
pg/mL §
ELISA;
Innotest;
Fujirebio
tau-p181
(CSF)
FTD-
bvFTD
(21)
41.67 ± 14.29
pg/mL §
ELISA;
Innotest;
Fujirebio
tau-p181
(CSF)
PD
(32)
41.19 ± 17.43
pg/mL §
ELISA;
Innotest;
Fujirebio
Gelb et al., 1999
tau-p181
(CSF)
PSP
(20)
31.5 ± 12.81
pg/mL §
ELISA;
Innotest;
Fujirebio
tau-p181
(CSF)
VaD
(12)
44.58 ± 20.78
pg/mL §
ELISA;
Innotest;
Fujirebio
tau-p181
(Plasma)
AD-
biomarker-pos
(121)
13.23 ± 6.41
pg/mL §
SIMOA;
Other/Not Specified;
In-house
tau-p181
(Plasma)
FTD-
bvFTD
(21)
7.85 ± 5.19
pg/mL §
SIMOA;
Other/Not Specified;
In-house
tau-p181
(Plasma)
PD
(32)
8.55 ± 7.29
pg/mL §
SIMOA;
Other/Not Specified;
In-house
Gelb et al., 1999
tau-p181
(Plasma)
PSP
(20)
6.75 ± 2.5
pg/mL §
SIMOA;
Other/Not Specified;
In-house
tau-p217
(CSF)
AD-
biomarker-pos
(121)
608.96 ± 360.4
pg/mL §
Electrochemiluminescence;
Other/Not Specified;
Meso Scale Discovery
tau-p217
(CSF)
CTRL-
biomarker-neg
(224)
45.77 ± 28.57
pg/mL §
Electrochemiluminescence;
Other/Not Specified;
Meso Scale Discovery
tau-p217
(Plasma)
AD-
biomarker-pos
(121)
7.5 ± 3.92
pg/mL §
Electrochemiluminescence;
Other/Not Specified;
Meso Scale Discovery
tau-p217
(Plasma)
CTRL-
biomarker-neg
(224)
0.89 ± 1.05
pg/mL §
Electrochemiluminescence;
Other/Not Specified;
Meso Scale Discovery
tau-total
(Plasma)
AD-
biomarker-pos
(121)
2.13 ± 1.1
pg/mL §
SIMOA;
Other/Not Specified;
Quanterix
tau-total
(Plasma)
CTRL-
biomarker-neg
(224)
1.61 ± 0.55
pg/mL §
SIMOA;
Other/Not Specified;
Quanterix
tau-total
(Plasma)
FTD-
bvFTD
(21)
1.82 ± 0.73
pg/mL §
SIMOA;
Other/Not Specified;
Quanterix
tau-total
(Plasma)
PD
(32)
1.47 ± 0.61
pg/mL §
SIMOA;
Other/Not Specified;
Quanterix
Gelb et al., 1999
tau-total
(Plasma)
PSP
(20)
1.68 ± 0.65
pg/mL §
SIMOA;
Other/Not Specified;
Quanterix
tau-total
(Plasma)
VaD
(12)
1.97 ± 0.49
pg/mL §
SIMOA;
Other/Not Specified;
Quanterix

§ Data supplied to Alzforum by author

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Comments

  1. The paper by Palmqvist et al. on blood plasma phospho-tau 217 is a remarkable clinical study clearly demonstrating the value of phospho-tau 217 for identifying AD pathology. These findings advance our understanding of how p-tau217 is related to amyloid and tau PET and the stages of AD, and how it can be utilized as a blood biomarker. By using cutoffs and AUC analyses, the group was able to demonstrate outstanding concordance of blood plasma p-tau217 to amyloid and tau PET thresholds.

    Based on findings in CSF from the DIAN study (Barthélemy et al., 2020), some outstanding questions remain related to the causal relationship of p-tau217 and other tau species with amyloid plaques and neurofibrillary tangles. For example, p-tau217 increases two decades before tau PET increases are detected in DIAN. Does this indicate that p-tau217 is a reaction to amyloid plaques that precedes tau pathology? Or is tau pathology beginning two decades before it’s detectable by tau PET? Similarly, p-tau217 decreases after symptom onset, while tau PET signal and clinical dementia is increasing. This evidence strongly suggests that p-tau217 (and p-tau181) are not direct measures of tau pathology, but rather may be a reaction to amyloid plaques that later is associated to tau pathology.

    Nico Barthélemy’s work identified p-tau217 as a promising biomarker, and that CSF p-tau217 performed better than p-tau181 to identify amyloid PET positivity (2016 CTAD presentation; Barthélemy et al., 2017; Barthélemy et al., 2020). These findings are supported by extensive brain mass-spectrometry analyses of multiple tau isoforms and species (Barthélemy et al., 2019). 

    Our latest work identifies that plasma p-tau by mass spectrometry continues to produce better associations with amyloid plaques, and that it is feasible to measure blood plasma p-tau181 and p-tau217 in a mass-spec multiplex assay. Further work will be needed to better understand, and interpret, changes in p-tau217 and other tau biomarkers in AD.

    References:

    . A soluble phosphorylated tau signature links tau, amyloid and the evolution of stages of dominantly inherited Alzheimer's disease. Nat Med. 2020 Mar;26(3):398-407. Epub 2020 Mar 11 PubMed.

    . Tau hyperphosphorylation on T217 in cerebrospinal fluid is specifically associated to amyloid-β pathology. bioRxiv. November 30, 2017.

    . Cerebrospinal fluid phospho-tau T217 outperforms T181 as a biomarker for the differential diagnosis of Alzheimer's disease and PET amyloid-positive patient identification. Alzheimers Res Ther. 2020 Mar 17;12(1):26. PubMed.

    . Tau Phosphorylation Rates Measured by Mass Spectrometry Differ in the Intracellular Brain vs. Extracellular Cerebrospinal Fluid Compartments and Are Differentially Affected by Alzheimer's Disease. Front Aging Neurosci. 2019;11:121. Epub 2019 May 21 PubMed.

    View all comments by Randall Bateman

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