Platform extension for second‐generation Elecsys β‐amyloid(1−42), pTau, and tTau cerebrospinal fluid (CSF) immunoassays on cobas e analyzers

Background The Elecsys® β‐Amyloid(1−42) CSF Gen2 (Abeta42 Gen2), Phospho‐Tau (181P) CSF Gen2 (pTau Gen2), and Total‐Tau CSF Gen2 (tTau Gen2) immunoassays currently in development for the detection of Alzheimer’s disease will become available on cobas e 801 and e 402 platforms (Roche Diagnostics International Ltd). This study evaluated the analytical performance of second‐generation Elecsys CSF immunoassays on extended cobas e platforms. Method CSF samples were analyzed using the Elecsys Abeta42 Gen2, pTau Gen2, and tTau Gen2 CSF immunoassays on cobas e 801 and e 402 analyzers at the Roche Penzberg site. Repeatability and intermediate precision were evaluated per the CLSI EP05‐A3 protocol using two assay‐specific PreciControl samples and a panel of native CSF samples covering the assay measuring range (two runs per day with two aliquots over 21 days; n=84). Coefficients of variation (CVs [%]) and standard deviations were calculated. Method comparisons (lot‐to‐lot and between platform) were conducted according to the CLSI EP09 protocol. For the lot‐to‐lot comparison, native CSF samples were analyzed for Lot A and B with all three Elecsys immunoassays on cobas e 801. For the platform comparison, native CSF samples were analyzed with all three Elecsys immunoassays on cobas e 801 and e 402. Passing‐Bablok regression and Pearson’s correlation were calculated. Result Good precision was observed for all three Elecsys CSF immunoassays on cobas e 801. CVs for repeatability were ˂5% for Elecsys Abeta42 Gen2 and ˂2% for Elecsys pTau Gen2 and tTau Gen2, and for intermediate precision were ˂6%, ˂3%, and ˂2% for Elecsys Abeta42 Gen2, pTau Gen2, and tTau Gen2, respectively (Tables 1‐3). Method comparison experiments demonstrated good lot‐to‐lot agreement on cobas e 801 (Pearson’s r: 0.999−1.000) and good platform agreement between cobas e 801 and e 402 (Pearson’s r: 0.999−1.000) (Table 4). Broader on‐board and calibration stability were observed for the Elecsys CSF immunoassays on cobas e 801 and e 402 compared with cobas e 601 (data not shown). Conclusion Second‐generation Elecsys CSF immunoassays demonstrated good analytical performance on extended cobas e platforms, including good precision, lot‐to‐lot and platform agreement, supporting their use and the implementation of CSF biomarkers in clinical routine.