Roche Cleared an Alzheimer’s Blood Test With Three Result Categories. The Middle One Is Where PET Survives.
- The FDA cleared Roche‘s Elecsys pTau217 plasma test on 24 August 2026, developed with Eli Lilly, to aid identification of amyloid pathology in people aged 55 and older showing signs or complaints of cognitive decline. Roche calls it the first and only single-biomarker blood test supporting both rule-in and rule-out using one set of validated cutoffs across primary and specialty care.
- The assay returns three result categories: positive, intermediate and negative. It is explicitly not a stand-alone test, and Roche positions it as helping clinicians decide when further evaluation including PET imaging or CSF testing is appropriate.
- The test runs on Roche’s installed base of more than 4,500 cobas instruments in the US, requiring no additional instrumentation. Roche frames the approach as one assay, one biomarker and one set of cutoffs.
- Safety and effectiveness have not been established for predicting development of dementia or other neurologic conditions, or for monitoring the effect of therapeutic products. Roche cites an estimated 75% of people living with dementia as remaining undiagnosed.
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Reported as a blood test replacing a scan, this is closer to a triage instrument. A three-way output means some patients resolve neither way, and those patients still go to imaging.
- The intermediate band is the number that decides how much PET volume moves. Roche gives 3 result categories and does not state what proportion lands in the middle. Everything about displacement economics turns on that figure. Ask for the intermediate rate before modelling any shift in imaging demand.
- The moat is placement, not the biomarker. More than 4,500 cobas instruments are already installed in US laboratories, so adoption needs a menu addition rather than capital equipment. A rival assay with equal or better performance still has to win instrument placement first.
- It selects candidates and cannot follow them. The label does not establish use for monitoring therapeutic effect, which matters now that anti-amyloid therapies are in clinical use. Note too that agreement is reported against amyloid PET, and 3 cleared PET quantification packages have themselves been shown to disagree at the threshold.
Read the original source (Roche Diagnostics) →
GeographyUnited States