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FDA Clears Roche’s Beta-Amyloid and Total-Tau Assays for Alzheimer Assessment
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With the approval, Roche has 3 FDA-cleared tests that are reflective of the main Alzheimer disease pathologies and help clinicians more completely define the disease biologically.
Brad Moore
According to an announcement, the FDA has granted 510(k) clearance to Roche for its Alzheimer disease (AD) cerebrospinal fluid Elecsys assays—including beta-amyloid1-42 CSF II (Abeta42) and total tau (tTau) assay. Used for individuals ages 55 and older being evaluated for AD and other causes of cognitive impairment, the new Elecsys tTau/Abeta42 ratio will be available in the final quarter of this year.1
As changes in beta-amyloid and total-tau levels occur at early stages of the disease, the assays are designed to detect AD pathology in earlier stages of the disease. The ratio of these biomarkers is consistent with a negative amyloid PET scan if the result is less than or equal to the cutoff, and with a positive amyloid PET scan if the result is above the ratio cutoff.
"With the increasing likelihood of broad availability of new, Alzheimer disease–specific therapies, now is the time for healthcare professionals and institutions to prepare to meet the demand for diagnostic methods to streamline and accelerate the path to the right treatment, at the right time, for people with Alzheimer,” Brad Moore, president and chief executive officer of Roche Diagnostics North America, said in a statement. "An early and accurate diagnosis can help patients, caregivers and physicians determine a path forward, and the Elecsys CSF assays support diagnosis at early disease stages, when treatment is most effective."
These tools are intended to be used with other clinical diagnostic evaluations during the diagnostic process for patients with potential AD, and thus, a positive tTau/Abeta42 ratio result in CSF does not establish a diagnosis of AD. Confirmation of amyloid pathology, a requirement for newly approved AD medications, has been typically done through FDA-cleared CSF tests and PET scan imaging.
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The approval of the tTau/Abeta42 assays comes less than a year after the FDA cleared Roche’s Abeta42 and phosphor-tau181 (pTau181) assays. The combination of all 3 assays are reflective of the main AD pathologies and help clinicians more completely define the disease biologically, facilitating a diagnosis of inclusion, the company noted. In the original approval, Roche noted that its AD assays “achieve 90% concordance” with amyloid PET scans.2
In an analytical performance, reproducibility, method comparison with commercially available assays, investigators noted that the Elecsys pTau181 CSF assay, “demonstrated good correlation with commercially available tau assays,” showing high sensitivity (limit of quantitation, 4 pg/mL) and linearity over the measuring range (8-120 pg/mL), which covering the entire concentration range. Lot-to-lot and platform comparability demonstrated good consistency (Pearson r, 1.000).3
Similarly, the Elecsys Abesta42 assay showed high correlation with the Innotest β-amyloid1-42 (Spearman ρ, 0.954), Inno-Bia AlzBio3 (Spearman ρ, 0.864), and ADx-Euroimmun ß-amyloid1-42 ELISA (Pearson r, 0.925). Compared with liquid chromatography-tandem mass spectrometry measurements, the Elecsys assay reported a correlation with Roche Diagnostics- and University of Pennsylvania-developed methods (Pearson r, 0.949 and 0.943, respectively).4
In July 2022, Roche announced that the FDA granted breakthrough therapy designation to its Elecsys Amyloid Plasma Panel, a minimally invasive and easily accessible solution that enables the measurement of AD biomarkers from a blood sample. Of note, these assays remain in development.5
