Research affirms high diagnostic accuracy of blood test for Alzheimer’s

ALZpath’s pTau217 test could be as accurate as invasive spinal tap, new study suggests.

Alzheimer’s diagnostics company ALZpath has announced new findings that show its proprietary blood test for Alzheimer’s disease delivers high diagnostic accuracy and consistency in identifying amyloid and tau in the brain [1].

The findings suggest that ALZpath’s blood-based biomarker assay for phosphorylated tau at residue 217 (handily shortened to pTau217) could be as accurate as a standard lumbar puncture, a procedure which is both invasive and incredibly painful.

Longevity.Technology: We first wrote about the idea of using pTau217 as a diagnostic test for Alzheimer’s back in 2020, quoting Eric Reiman, MD, Executive Director of Banner Alzheimer’s Institute in Phoenix: “Blood tests like p-tau217 have the potential to revolutionize Alzheimer’s research, treatment and prevention trials, and clinical care.”

Well, he wasn’t wrong. Alzheimer’s disease is one of the areas in medicine with the highest unmet medical need, but even though new drugs are starting to become available, they slow the progression of early-stage Alzheimer’s disease. This means early, accurate diagnosis is vital, and a blood test that could do that quickly and efficiently would, indeed, revolutionize Alzheimer’s treatment.

Cerebrospinal fluid (CSF) biomarkers are considered one of the most accurate tests of Alzheimer’s pathology available, in addition to positron emission tomography (PET). However, as well as being painful and invasive, the cost is typically 2-3 times higher than blood-based testing, and is more difficult to administer at the scale that will be required with the availability of a new generation of disease-modifying treatments.

ALZpath hopes to transform Alzheimer’s disease diagnosis and monitoring, and provide accurate and accessible tools for researchers and healthcare professionals worldwide.

The study employed the ALZpath pTau217 ultra-sensitive immunoassay, developed on the Single molecule array (SimoaTM) platform in blood, and evaluated the performance of the ALZpath pTau217 assay in three independent clinical studies as part of an international collaboration between researchers in Sweden, Spain, Canada and the US. The combined studies included 786 participants [1].

The ALZpath pTau217 assay showed high diagnostic accuracy in identifying elevated amyloid and tau in the brain (up to 96% and 97% accuracy, respectively). The results were published in JAMA Neurology.

The accuracies reported were significantly higher than other plasma biomarker combinations and equivalent to CSF biomarkers. Longitudinally, ALZpath’s pTau217 test in blood showed an annual increase in individuals with amyloid plaques, with the highest increase observed in those who also had tau pathology.

“This is an instrumental finding in blood-based biomarkers for Alzheimer’s, paving the way for the clinical use of the ALZpath pTau 217 assay,” stated Professors Kaj Blennow and Henrik Zetterberg from the University of Gothenburg, co-authors on the publication. “This robust assay is already used in multiple labs around the globe.”

“What was impressive with these results is that the blood test was just as accurate as advanced testing like cerebrospinal fluid tests and brain scans at showing Alzheimer’s disease pathology in the brain,” Nicholas Ashton, a professor of neurochemistry at the University of Gothenburg in Sweden and one of the study’s lead authors, told CNN, adding that the study demonstrates that a test for Alzheimer’s is now close to “being prime-time [2].”

Dr Andreas Jeromin, ALZpath Chief Scientific Officer, said: “This diagnostic capability offers increasingly vital aid in medical management and treatment decisions for Alzheimer’s, especially as new disease-modifying treatments become more accessible.”

The news was welcomed by Alzheimer’s charities and organizations; Dr Sheona Scales, Director of Research at Alzheimer’s Research UK, said the test “has huge potential to revolutionise diagnosis for people with suspected Alzheimer’s [3].”

The ALZpath pTau217 assay will be available for clinical use as ALZpath Dx later this month and is part of a broader neuro biomarker portfolio in development. The ALZpath pTau217 test will also be commercially available on other research and diagnostic platforms in support of global accessibility and scalability.

[1] https://jamanetwork.com/journals/jamaneurology/fullarticle/2813751
[2] https://edition.cnn.com/2024/01/22/health/alzheimers-blood-test-screening-study/index.html
[3] https://www.alzheimersresearchuk.org/detecting-alzheimers-disease-using-a-blood-test-could-be-just-as-accurate-as-standard-lumbar-punctures-study-shows/

Photograph: Ebrahim Lotfi/Shutterstock