FDA Watch: A New Blood Test for Accurate Alzheimer’s Detection

Alzheimer’s disease is dreaded not only because of its inexorable progression and the profound damage it wreaks on memory and the nervous system, but because it is often only diagnosed after symptoms appear. That often puts patients and their families in the unenviable position of having to make contingency plans quickly.

Bellingham, Washington-based Neurocode USA may have found a way to give Alzheimer’s patients more time—and perhaps more convenience—with its ALZpath DX assay, a laboratory-developed test that the company recently made available to the public.¹ The test relies on the Simoa^® single-molecule assay platform developed by Quanterix that recently received Breakthrough Device Designation from the U.S. Food and Drug Administration (FDA).² It is a form of immunoassay, which relies on the reaction of antibodies to determine results, according to Michael Metke, Neurocode’s medical science liaison.

The test measures levels of the protein phosphorylated tau at threonine 217, known as pTau217, a biomarker that can indicate the presence of amyloid buildup in a patient’s brain. In practical terms, using ALZpath DX could mean that patients suspected of having the neurodegenerative disorder may no longer have to undergo a more invasive cerebrospinal fluid test or a PET scan, which involves exposure to radiation. A study recently published in JAMA Neurology concluded the ALZpath DX test demonstrated an accuracy higher than other blood-based biomarker combinations and equivalent to performing a spinal tap for a diagnosis.³

Moreover, ALZpath can diagnose Alzheimer’s in its early stages. That can give patients more options in terms of obtaining treatments, as disease therapies for Alzheimer’s are more effective early in the disease’s progression. It can also better identify candidates for clinical trials for new medications.

The test can be performed with as little as a half milliliter of blood plasma, according to Quanterix spokesperson Olivia Mannion. The assay can be performed at one of Quanterix’s labs, which is operated under the Lucent Diagnostics brand. Other laboratories have the option of installing the Simoa platform and performing the test in-house.

Metke also noted that the AlZpath Dx test can also “be used in conjunction with other assays to provide differential diagnosis between Alzheimer’s and other dementias.”

The company is also working to develop other assays that could diagnose Alzheimer’s even before symptoms appear.

“There is hope that other blood-based biomarkers, including some of the other phospho-Tau forms (pTau231, for example) may be helpful for predicting increased likelihood of developing Alzheimer’s several years before the onset of symptoms,” Metke said in an email. “But work is still in progress to determine whether these biomarkers are accurate enough for clinical use in this context.”

He added that “Neurocode is currently working on additional blood tests that will provide even better ability to discriminate [between] different dementias.” The company has also developed a biomarker test for neurofilament light chain (NfL), which can expose other forms of neuronal damage and is linked to other forms of dementia.

Metke said that a new PLA code is being developed for AlZpath Dx so it will be covered by insurers.

Takeaway: Patients suspected of having Alzheimer’s now have less invasive options to help reach a diagnosis.

References:

1. 1. https://www.prnewswire.com/news-releases/neurocode-launches-groundbreaking-ptau217-blood-test-for-alzheimers-disease-clinical-diagnosis-302077956.html
   2. https://www.businesswire.com/news/home/20240304898657/en/Quanterix-Granted-Breakthrough-Device-Designation-from-U.S.-FDA-for-Blood-Based-p-Tau-217-Test-for-Alzheimer%E2%80%99s-Disease
   3. https://jamanetwork.com/journals/jamaneurology/fullarticle/2813751

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Laboratory tests that were approved by the U.S. Food and Drug Administration in recent weeks include:

New FDA Approvals and Emergency Use Authorizations (EUAs)

Though not cleared or approved by the FDA, significant laboratory test launches and Breakthrough Device Designations in the US during the period include:

Key US Laboratory Test Launches and Breakthrough Device Designations

New CE marks and global certifications

There were no significant EU or global approvals during the period