This week, the FDA approved the first blood-based diagnostic test for Alzheimer’s disease (AD). The test, known as “Lumipulse G pTau 217/β-Amyloid 1-42 Plasma Ratio,” is designed to detect amyloid plaques identified in adults over 55 who have exhibited AD symptoms. This will reduce reliance on PET scans.
According to Dr. Howard Fillit, an AD Foundation science official, over seven million people in the United States are known to have the disorder, and that number is on track to double by 2050.
The new test combines these concentrations into a numerical ratio of p-tau 217 and beta-amyloid 1-42. Phosphorylated tau 217 is a protein in the brain that becomes tangled in Alzheimer’s.
Plasma samples from 499 adults with dementia formed the basis of the study. The test results were validated against amyloid PET or CSF tests and showed a 91.7% positive predictive value and 97.3% negative predictive value. The FDA noted that these findings show the new blood test can reliably predict the presence or absence of amyloid pathology associated with Alzheimer’s disease for patients with dementia.
Risks related to the blood test include a possible false positive or false negative.
A Message from the FDA
The new test was not developed for screening purposes or as an independent diagnostic test. Therefore, according to the FDA, additional tests are recommended to determine the most appropriate treatments.
The FDA clearance of this first blood test to detect Alzheimer’s marks a major milestone for patients and clinicians. The approval comes at a pivotal time as the number of people developing the disease continues to increase exponentially.
In 2022, the FDA issued a clearance to Fujirebio Diagnostics in Japan for the first Lumipulse G β‐Amyloid Ratio. Fujirebio is also responsible for this newly announced blood test.
