ARUP Laboratories now provides a blood test for phosphorylated tau 217 (pTau 217) to assist in identifying whether cognitive decline symptoms in patients ages 60 years and older are related to Alzheimer's disease (AD) pathology. As this biomarker can be detected in blood, this test is a minimally invasive and broadly accessible diagnostic tool that may facilitate earlier detection of AD.

"The advent of disease-modifying therapies has accelerated the need for early diagnosis since diagnostic delays for Alzheimer's disease could adversely affect outcomes," said Heather Nelson, PhD, DABCC, ARUP medical director of Clinical Chemistry. "This test offers a less invasive and more accessible way to provide evidence of AD pathology than alternate means."

According to the Alzheimer's Association, AD is the most common cause of dementia, accounting for 60–80% of cases, and brain changes may begin 20 years or more before symptoms start. These brain changes include the accumulation of beta-amyloid and tau proteins.

ARUP validated the pTau 217 test using carefully characterized samples from Eli Lilly and Company's Phase 3 TRAILBLAZER-ALZ 2 trial. The validation cohort included blood specimens and results from amyloid positron emission tomography (amyloid-PET) imaging of 524 individuals.

"Not only did we have data for the method comparison, but we were also able to reference the PET imaging data, which further increased our confidence in the quality of this test," said Sonia La`ulu, MBA, C(ASCP).

Conventional testing of cognitively impaired individuals by evaluation of biomarkers in cerebrospinal fluid (CSF) or by amyloid-PET requires invasive procedures that are difficult to access for many patients. By contrast, plasma biomarkers offer a minimally invasive alternative to detect AD pathology.

"In many clinical studies, pTau 217 has been shown to be an effective biomarker of AD pathology, outperforming other biomarkers," said Kelly Doyle, PhD, DABCC, FADLM, ARUP medical director of Special Chemistry, Endocrinology, and Mass Spectrometry. "Blood-based pTau 217 correlates well with amyloid-PET results and CSF biomarkers but with the benefit of being minimally invasive and broadly accessible."

ARUP's test will be performed on Quanterix's SP-X® platform with the Quanterix Simoa® assay kit, which uses pTau 217 antibody technology licensed from Eli Lilly and Company.