New PrecivityAD2 Blood Test as Accurate as CSF Biomarker and Amyloid PET Testing

Two studies presented at the 2024 meeting of the Alzheimer’s Association International Conference (AAIC) suggest that high-performance blood tests are accurate and effective at assessing for evidence of Alzheimer disease (AD).

In the first study, a total of 698 participants were tested using the PrecivityAD2 blood test for Amyloid Probability Score-2 (APS2), which was shown to significantly outperform clinicians in identifying AD. The test, which uses a combination of plasma phosphorylated-tau217 to not-phosphorylated-tau217 ratio (%p-tau217) and the ratio of amyloid types (Aβ42/Aβ40), identified AD with an accuracy rate of approximately 90%. Specialists, by comparison, were 73% accurate, and primary care physicians were 63% accurate when evaluating 513 participants for AD without the use of the blood test.

In the second study, the predictive capability of plasma p-tau217 blood tests as a potential prescreening tool was evaluated in a population of 334 individuals assessed in the primary care setting as cognitively unimpaired, who had tested positive for Aβ pathology via PET or cerebrospinal fluid (CSF) biomarker testing. The plasma p-tau217 tests showed an accuracy of 81% in predicting the participants’ Aβ status, which was shown to be improved further to positive predictive values (PPVs) of up to 95% following the subsequent use of CSF testing. According to the study authors, the findings suggest that p-tau217 testing may have applications in clinical trials for pre-screening for preclinical AD.

“Blood tests are revolutionizing Alzheimer’s detection, diagnosis and ultimately treatment, and this recent JAMA study is further validation that C2N’s blood test is highly accurate and sensitive," said Howard Fillit, MD, Co-Founder and Chief Science Officer of the Alzheimer's Drug Discovery. "With more studies like this one, blood tests will soon replace more invasive and costly PET scans as the standard of care and serve as the first line of defense in diagnosing the disease. After many years of research, the field is in a place where we have novel biomarkers and diagnostics to support a diagnosis, like how cholesterol is used to help detect heart disease. The diagnostic framework for Alzheimer's—an incredibly complex disease—is constantly evolving. As we usher in the new era of care, we are moving closer to the day when blood tests will be complemented by digital tools to provide precise and timely diagnoses and risk assessments backed by numerous data points, complementing existing cognitive tests,”