Blood-based biomarkers are reshaping how Alzheimer’s disease is studied and diagnosed. Yet many assays demand large plasma volumes and lose accuracy with archived or repeatedly thawed samples, limiting the utility of decades of biobanked material. These challenges slow progress toward scalable, reliable testing.
The need for assays that combine sensitivity, precision and efficiency has never been greater.
This case study shows how a next-generation pTau 217 assay achieves higher accuracy than existing platforms using only 1 µL of diluted plasma, while maintaining robust performance across freeze-thawed samples and diverse cohorts.
Download this case study to discover:
- How low-volume sampling can unlock broader use of biobank collections
- Performance comparisons across leading pTau 217 assays
- Implications for scaling blood-based biomarker testing in Alzheimer’s research
614 McKinley Place NE
Minneapolis, MN 55413
bio-techne.com
1-800-343-7475
www.spear.bio
CASE STUDY
From Precious Samples to Powerful Insights
How the Spear UltraDetect™ pTau 217 Assay Unlocks Greater Discrimination of Amyloid
Positives Using 1 µL of Diluted Sample
“The SPEAR UltraDetect pTau 217 assay gave us larger effect sizes and higher accuracy than other assays in
distinguishing amyloid positives from negatives, while using over 100-fold less plasma. Even with samples that
had been freeze-thawed multiple times, the performance was remarkably robust.”
— Dr. Thomas Karikari, Ph.D., Assistant Professor, University of Pittsburgh
A leader in Alzheimer’s fluid biomarker research
Dr. Thomas Karikari, Assistant Professor at the University of
Pittsburgh, is a leading figure in the development of bloodbased biomarkers for Alzheimer’s disease (AD). Dr. Karikari’s
pioneering research has shaped how plasma biomarkers are
applied in diagnosis, monitoring, and clinical studies for AD.
At the 2025 Alzheimer’s Association International Conference
(AAIC) in Toronto, Dr. Karikari’s team presented results from
a collaboration with Spear Bio. The study compared the
Spear UltraDetect™ pTau 217 assay with the Simoa®
ALZpath assay and the Lumipulse® pTau 217 assay across two
distinct cohorts: a memory clinic cohort from the University of
Pittsburgh Alzheimer's Disease Research Center (ADRC) and a
community-based cohort from the Human Connectome Project.
Meeting the challenge
Blood-based biomarkers like pTau 217 are transforming
Alzheimer’s research. Yet measuring them consistently across
diverse cohorts isn’t easy. Many available assays require large
volumes of plasma, and their performance can be compromised
when working with archived samples that have been
freeze-thawed multiple times. For studies that rely on
biobanked samples collected over decades, these limitations are
particularly pressing.
Dr. Karikari’s group turned to the Spear UltraDetect™ pTau 217
Transforming research possibilities
For Dr. Karikari and his team, the Spear UltraDetect™ pTau 217 assay provided more than just numbers. It
opened the door to making full use of long-standing biobank collections, reducing the burden of large
sample volumes, and pushing biomarker studies into broader populations where only small-volume
samples are available. By uniting sensitivity, efficiency, and robustness, this assay brings researchers closer
to reliable, scalable blood-based testing for Alzheimer’s disease, delivering performance in line with
Alzheimer’s Association guidelines for biomarker-based screening and confirmatory testing.
the assay in two different settings: a memory clinic cohort from
the University of Pittsburgh ADRC and a community-based cohort
from the Human Connectome Project, where participants were
largely cognitively normal.
A story of performance
In the memory clinic cohort of 119 participants, the SPEAR assay
consistently outperformed the Simoa® ALZpath assay. It
achieved a 4.7-fold difference between amyloid-positive and
amyloid-negative groups and resulted in an AUC of 0.95,
compared to a 3.0-fold difference and AUC of 0.90 for ALZpath.
The Spear assay also showed 93% concordance with amyloid PET
imaging, even though many of the plasma samples had been
collected years before the PET scans. Notably, the performance
of the SPEAR assay remained robust for samples that have gone
through four to five freeze-thaw cycles with mean CV of 5.2%,
demonstrating exceptional precision.
In the community-based cohort, where most participants were
cognitively normal, the Spear assay was compared to the
Lumipulse® pTau 217 assay. Once again, it delivered stronger
results. The UltraDetect assay achieved an AUC of 0.90 versus
0.82 for Lumipulse and showed a 3.0-fold separation between
amyloid-positive and amyloid-negative groups, compared to
2.1-fold with Lumipulse. Even more striking, the Spear assay
required just 1 µL of diluted plasma—over 100 times less than
the Lumipulse assay—yet still maintained superior accuracy after
six freeze-thaw cycles.
For research use only.
