FDA Clears Roche-Eli Lilly Blood Test That Spots Alzheimer’s Pathology Without a Spinal Tap or Brain Scan
The Elecsys pTau217 assay measures a key protein in plasma and can indicate whether amyloid changes linked to Alzheimer’s are present. It runs on existing laboratory machines already installed across the United States.
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A simple blood draw may soon replace some of the more invasive steps doctors take when they suspect Alzheimer’s disease. On Monday the U.S. Food and Drug Administration cleared the Elecsys pTau217 plasma test, developed by Roche in partnership with Eli Lilly, for use in adults aged 55 and older who show signs of cognitive decline.
The test looks for phosphorylated tau 217, a protein that rises when amyloid plaques begin to form in the brain. Results fall into three categories—positive, intermediate or negative—and are meant to be read alongside a patient’s clinical history and other findings. Roche emphasises that the assay is not a stand-alone diagnosis.
Until now, confirming amyloid pathology usually required either a PET scan or a lumbar puncture to analyse cerebrospinal fluid. Both methods are accurate but costly, limited in availability and, in the case of the spinal tap, uncomfortable. The new blood test can be run on more than 4,500 Roche cobas analysers already operating in U.S. laboratories. Labcorp and Quest Diagnostics have said they plan to offer the test through their national networks, which should widen access quickly.
European regulators granted CE marking to the same assay in May. Fujirebio’s Lumipulse test, cleared by the FDA in 2025, was the first blood-based option for Alzheimer’s assessment; Elecsys pTau217 is the first single-biomarker assay cleared for both ruling in and ruling out amyloid pathology with the same cut-offs in primary and specialty care.
An estimated three-quarters of people living with dementia remain undiagnosed. Earlier, less burdensome testing could help more patients enter treatment pathways sooner, especially as disease-modifying therapies continue to reach the market. Clinicians will still need to interpret results carefully and combine them with cognitive testing and imaging when appropriate.
The clearance arrives at a moment when pharmaceutical companies and diagnostic firms are racing to simplify Alzheimer’s work-ups. For patients and families facing the uncertainty of memory loss, a routine blood sample that can point toward or away from the most common cause of dementia represents a practical step forward.
