Alzheimer's Blood Test Comes to the Clinic

Pauline Anderson

October 30, 2020

The first blood test to detect the presence of amyloid, a hallmark of Alzheimer's disease (AD), is now available for clinical use, the company behind the test's development, C2N Diagnostics, has announced. The availability of the noninvasive, easily administered test is being called a milestone in the early detection and diagnosis of AD.

The blood test "introduces a new option for patients, families, and the medical community that have eagerly awaited innovative tools to address Alzheimer's troubling problems," Joel B. Braunstein, MD, CEO of C2N Diagnostics, said in a press release.

"This is really an important advance," said Howard Fillit, MD, founding executive director and chief science officer of the Alzheimer's Drug Discovery Foundation (ADDF), which partially funded the development of the test, in a separate press release.

"You can now walk into your doctor's office to get a blood test to help detect Alzheimer's disease," said Fillit. "This test answers a critical need for less costly and accessible diagnostic testing in memory and dementia care."

A Word of Caution

However, Maria C. Carrillo, PhD, chief science officer, Alzheimer's Association, highlighted the need for caution.

The test is "very new," experts have only "limited information" about it, and it is only available by prescription from a healthcare provider for patients with cognitive impairment, Carrillo told Medscape Medical News.

"The test is not FDA approved and it does not, on its own, diagnose Alzheimer's," added Carrillo. "Without FDA review, healthcare providers lack the agency's guidance for how to use it when making decisions about a person's health or treatment."

Carrillo also noted that the test has only been studied in a limited number of individuals and that few data are available regarding underrepresented populations.

"As a result, it is not clear how accurate or generalizable the results are for all individuals and populations," she noted.

Another factor to consider, said Carrillo, is that the test is not covered by insurance, including Medicare and Medicaid.

How It Works

The test (PrecivityAD) is for use in patients with cognitive impairment. It requires a very small blood sample ― as little as a teaspoon ― from the patient's forearm. The physician sends the sample to C2N Diagnostic's specialized laboratory, where it's analyzed using mass spectrometry to measure concentrations of amyloid beta 42 and 40 and to detect the presence of apolipoprotein E isoforms.

The lab report, which is sent to the patient's physician, details biomarker levels and provides an overall combined score, known as the Amyloid Probability Score, to assess the likelihood of low, intermediate, or high levels of amyloid plaque in the brain.

The company reports that, on the basis of data from 686 patients older than 60 years who had subjective cognitive impairment or dementia, the test correctly identified brain amyloid plaque status, as determined by quantitative amyloid positron-emission tomography (PET) scans, in 86% of the patients. In the analysis, the area under the curve for the receiver operating characteristic was 0.88.

The company notes that the test, the results of which require interpretation by a healthcare provider, is an important new tool to aid physicians in the evaluation process.

The new blood test is currently available in 45 states, the District of Columbia, and Puerto Rico.

C2N Diagnostics is moving ahead with development of a brain health panel to detect multiple blood-based markers for AD to aid in disease staging, treatment monitoring, and differential diagnosis.

The ADDF believes the path to approval of treatments of AD starts with a better diagnosis, Fillit said in his organization's press release.

"Investing in biomarker research has been a core goal for the ADDF because reliable, accessible, and affordable biomarkers for Alzheimer's diagnosis are critical to our ability to find drugs to prevent, slow, and even cure the disease. Our funding helped bring the first PET scan to market and now has helped bring the first blood test to market," he said.

In addition to the ADDF, the National Institutes of Health, the GHR Foundation, and the BrightFocus Foundation contributed funding for the development of the amyloid blood test.

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