The U.S. Food and Drug Administration (FDA) on Monday (August 24) approved the Elecsys Phospho-Tau (217P) plasma test (pTau217) developed in collaboration between Roche and Eli Lilly. The test is intended for people aged 55 and older who have signs, symptoms, or complaints of cognitive decline. It is used to help determine whether there is amyloid pathology associated with Alzheimer’s disease. Test results are categorized as positive, intermediate, or negative and must be interpreted together with other clinical information; they cannot be used alone as a diagnosis. Pricing has not yet been announced.
Roche said this is currently the only blood test that has received FDA approval, uses a single biomarker, and uses the same validated cutoff values in both primary care and specialty settings, while also supporting amyloid pathology assessment both for “inclusion” and for “exclusion.” The test measures phosphorylated tau 217 in plasma. Higher levels suggest that amyloid pathology is more likely present; lower levels suggest it is more likely absent. Intermediate results require further evaluation.
Roche’s North America president and CEO, Dan Malerack, said that approval allows assessment to be brought closer to where patients first seek care. Eli Lilly’s president of neuroscience, Carroll Ho, said the goal of the collaboration is to deliver the same test both to primary care (where most cognitive complaints first appear) and to specialists.
The intended population and things that cannot be done have been included in the label.
The indication is limited to people aged 55 and older who already show signs related to cognitive decline. Roche states that safety and efficacy have not been established for predicting the occurrence of dementia or other neurological diseases, nor for monitoring the effectiveness of therapeutic products. The results must be interpreted together with other diagnostic tools and clinical information.
Richard Isaacson, director of research at the Florida Neurodegenerative Disease Research Institute, told CNN that while the negative predictive value is adequate, the positive predictive value is not ideal; false positives, intermediate classifications, and issues such as sample handling and conditions like kidney disease or viral infections all increase the difficulty of interpretation. He advocates using a panel of tests rather than a single “Alzheimer’s blood test.”
The traditional methods for confirming amyloid pathology are PET imaging or cerebrospinal fluid testing, which are costly and invasive, and are not easy to obtain outside specialty centers. The International Alzheimer’s Association materials cited by Roche state that globally about 75% of people with dementia still have not been diagnosed; from the onset of symptoms to a confirmed diagnosis, it often takes about 3.5 years.
The existing 4,500 cobas instruments can run the test directly; Quest plans to go live in the fourth quarter.
The test is designed to run on more than 4,500 Roche cobas laboratory instruments already installed in the U.S., so laboratories do not need to purchase additional equipment. Roche said that assessment data show the test has a high concordance with amyloid PET imaging in people aged 55 and older who present with complaints related to cognitive decline. Specific sensitivity and specificity numbers are not listed separately in this press release.
Labcorp and Quest Diagnostics said on Monday that they will provide the test through their respective networks. Quest said it will launch, in the fourth quarter of 2026, a laboratory service for U.S. doctors and clinical trial partners using AD-Detect as the brand name, based on the FDA-approved test reagent, and plans to incorporate the reagent into subsequent combination testing in 2027. Quest also announced it will roll out, by the end of this month, a homegrown multi-biomarker laboratory-developed test that is not within the scope of this FDA approval.
The test received the European CE mark this May and was already on the market in Europe last month. Roche has not disclosed U.S. pricing.
This is the fourth FDA approval among blood tests of the same class.
In May 2025, Fujirebio’s Lumipulse became the first FDA-approved blood test for the supplemental assessment of Alzheimer’s disease. In October of the same year, Roche’s and Eli Lilly’s Elecsys pTau181 was approved, mainly for ruling out amyloid pathology in primary care. Last week, C2N Diagnostics’ PrecivityAD2 was approved, with an indicated age range as low as 40 years. pTau217 and pTau181 measure different phosphorylated sites.
Jared Brosch, a neurologist in the Division of Neurological Health at Indiana University, said that PET and cerebrospinal fluid can confirm amyloid pathology, but they are expensive and invasive, and many patients cannot access them; blood biomarkers expand assessment to more clinical care scenarios. Roche’s pipeline under development also includes an amyloid antibody delivered in the brain, troninemab (two Phase III trials), and an oral gamma-secretase modulator, nivegacetor (Phase II). These drugs are separate matters from the approval of this test.
The test has been approved to enter existing laboratory workflows in the United States. Quest’s branded service is planned to be made available to doctors in the fourth quarter of 2026. The company has not yet provided a timeline for how pricing, insurance reimbursement pathways, and the handling of intermediate results will be managed in everyday outpatient settings.
Roche’s cobas laboratory analysis system. The company says more than 4,500 units have been installed in the U.S., and pTau217 can run within the existing workflow.
The collaboration between Eli Lilly and Roche directs the same test to both primary care and specialty settings. How to refer patients after intermediate results, and whether a positive result directly triggers an assessment for anti-amyloid treatment, still depends on each organization’s own pathway and is not covered in this label.