Early Detection of Alzheimer Disease: Plasma Assays to Be Commercially Available

Highly sensitive assays designed to detect phosphorylated tau at position 217 (pTau217) are recent pivotal developments in Alzheimer disease and dementia research and diagnosis. 

Early detection and differentiation of neurologic diseases are important in providing proper care for patients. While pTau217 has been identified as an important biomarker in Alzheimer disease (AD), it exists at low levels in the plasma and requires sensitive detection for measurement. Until recently, the research and availability of pTau217 testing have been limited. 

Neurocode USA, Inc announced the launch of ALZpath Dx, a blood test used to detect pTau217 in patients with AD.¹ This is the first test made available as a Laboratory Developed Test (LDT) in facilities that are College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified. 

Some applications of this test include early detection and diagnosis of AD, improved stratification of patients in clinical trials, and enhanced patient care. These tests are required to be ordered by a health care professional and sample collection kits are distributed at affiliated phlebotomy sites. 

ALZpath has partnered with Alamar Biosciences in the development of the NULISAseq CNS Disease Panel 120 and the NULISAqpcr pTau-217 Assay, which uses ALZpath’s pTau217 antibody.² The NULISAseq CNS Disease Panel 120 is for highly multiplexed protein analysis in the study of protein pathways implicated in major neurologic disorders. The NULISAqpcr pTau-217 Assay is intended for studies on this biomarker for neurodegenerative disease research. 

Both assays are highly sensitive in detecting proteins from biofluids, allowing for an earlier diagnosis of neurologic diseases. These products are expected to ship in the second quarter of 2024.

“I’m especially excited about their ability to measure low abundant biomarkers from dried blood spots, a standard collection method that can be done in one’s home and really opens the possibility for early screening of the disease,” said Henrik Zetterberg, MD, PhD, professor and chief physician at the Institute of Neuroscience and Physiology at the University Gothenburg, Sweden, in the Alamar Biosciences news release.²

In January 2024, a cohort study published in JAMA Neurology³ evaluated the accuracy of pTau217 in detecting AD pathology. This study included 768 participants (average age, 66.3; 64.1% women) from 3 single-center observational cohorts. 

Researchers used the identification of elevated amyloid-beta plaques to evaluate high accuracy, demonstrating an area under the curve (AUC) range of 0.92 to 0.96 (95% CI, 0.89-0.99) across studies. In addition, high accuracy was observed in the identification of tau pathology, with an AUC of 0.93 to 0.97 (95% CI, 0.84-0.99) across studies. The researchers reported that these blood tests are as accurate as brain or cerebrospinal fluid (CSF) tests for diagnosing AD, but they are quicker in detecting results, more accessible and affordable, and less invasive. 

“Our findings demonstrate the substantial reduction of confirmatory testing, by approximately 80%, by implementing a 3-range approach for Aβ [amyloid-beta] positivity based on plasma p-tau217,” the researchers wrote in the JAMA Neurology study.³ They concluded, “These results emphasize the important role of plasma p-tau217 as an initial screening tool in the management of cognitive impairment by underlining those who may benefit from anti-amyloid immunotherapies.”

Disclosure: Multiple study authors declared affiliations with biotech, pharmaceutical, and or/device companies. Please see the original reference for a full list of disclosures.