FDA Clears Blood Test for Diagnosing Alzheimer’s Disease

The U.S. Food and Drug Administration (FDA) has granted 510(k) clearance for the Lumipulse® G β-Amyloid 1-42/pTau217 Plasma Ratio test, marking a significant advancement in the diagnostic landscape for Alzheimer’s disease (AD). Developed by Fujirebio Diagnostics, this in vitro diagnostic is the first FDA-cleared blood test specifically designed to assist in the clinical evaluation of Alzheimer's by detecting key biomarkers linked to the presence of cerebral amyloid plaques.

This regulatory milestone reflects a broader shift in the approach to diagnosing neurodegenerative conditions, moving away from highly invasive and resource-intensive methods such as cerebrospinal fluid (CSF) sampling and positron emission tomography (PET) imaging toward more scalable, minimally invasive assays.

The Lumipulse G test quantifies the ratio of two critical proteins in blood plasma: β-amyloid 1-42 (Aβ1-42) and phosphorylated tau at threonine 217 (pTau217). These biomarkers are central to Alzheimer’s pathophysiology. Aβ1-42 is involved in the extracellular deposition of amyloid plaques, while hyperphosphorylated tau proteins contribute to the formation of intracellular neurofibrillary tangles, both recognized as defining features of AD.

Rather than measuring amyloid deposition directly, the test leverages the pTau217/Aβ1-42 plasma ratio to infer the likelihood of amyloid plaque presence. This method provides clinicians with a biochemical signal that correlates closely with neuropathological status, supporting early-stage clinical decision-making.

The FDA's clearance is supported by data from a pivotal clinical study involving 499 individuals with signs of cognitive impairment. Plasma test results were benchmarked against PET imaging and CSF-based assays. The Lumipulse G test demonstrated 91.7% positive predictive agreement and 97.3% negative predictive agreement, indicating a high degree of concordance with established reference standards.

Furthermore, fewer than 20% of participants received indeterminate results, suggesting a high rate of diagnostic clarity for the majority of tested individuals. The assay is indicated for adults aged 55 years and older who are already exhibiting symptoms suggestive of cognitive decline, where differential diagnosis between Alzheimer’s and other dementias is clinically relevant.

Until now, blood-based assays for Alzheimer’s have been confined to laboratory-developed tests offered by commercial providers such as Quest Diagnostics and Labcorp. These tests, while clinically useful, lacked FDA review and clearance. The Fujirebio assay represents the first step toward standardized, regulated blood biomarker diagnostics that could be implemented across a broader range of healthcare settings.

By reducing dependence on CSF analysis and PET imaging, both of which are limited in availability and costly, this blood-based test can improve diagnostic equity and accelerate access to care. It is especially relevant as new disease-modifying therapies, such as monoclonal antibodies targeting amyloid, become available. These treatments are most effective when initiated early, underscoring the need for reliable tools to identify at-risk individuals before substantial neurodegeneration has occurred.

Fujirebio’s progress aligns with a larger trend toward innovation in neurodegenerative disease diagnostics. In parallel, the company has expanded its partnership with Japanese pharmaceutical firm Eisai to jointly develop and promote blood-based biomarkers for Alzheimer’s and related disorders. This builds upon earlier collaborations focused on CSF diagnostics and supports the development of companion diagnostics for therapeutics like lecanemab (Leqembi), Eisai’s anti-amyloid agent co-developed with Biogen.

Importantly, commercialization of therapies like Leqembi has been hindered by delays in diagnosis and limited access to confirmatory testing. Scalable biomarker tests such as Lumipulse G may help bridge this diagnostic gap, enabling earlier and more confident identification of eligible patients.

While this development represents a leap forward, its optimal use still requires careful integration into clinical workflows. Blood biomarker results must be interpreted in the context of comprehensive assessments, including neurological exams, cognitive testing, imaging, and family history. Clinicians must also consider individual variability in biomarker expression, comorbidities, and genetic factors such as APOE genotype when interpreting results.

To support this evolving paradigm, the Alzheimer’s Association is preparing to release clinical practice guidelines focused on the use of blood biomarkers in specialty care. These will provide evidence-based recommendations for appropriate patient selection and test interpretation and are expected to debut at the 2025 Alzheimer’s Association International Conference (AAIC).

With more than 6.9 million Americans currently living with Alzheimer’s, a number projected to nearly double by 2050, the need for scalable, cost-effective diagnostic strategies is pressing. Blood-based biomarker testing represents a crucial step in addressing this gap. Not only does it enable earlier intervention, but it also supports a more efficient clinical workflow that could ultimately reduce the economic and human burden of dementia.

The FDA’s clearance of the Lumipulse G blood test signals the beginning of a new chapter in Alzheimer’s diagnostics, one that is rooted in molecular science, guided by robust clinical data, and oriented toward accessibility and earlier disease detection. As the field continues to mature, further innovations in blood-based biomarker platforms may pave the way for even broader regulatory approvals and integration into routine cognitive health assessments.