title: Validation of ELISA methods for quantification of total tau and phosporylated-tau181 in human cerebrospinal fluid with measurement in specimens from two Alzheimer's disease studies.
abstract: Tau measurements in cerebrospinal fluid (CSF) are gaining acceptance as aids to diagnosis of Alzheimer's disease (AD) and differentiation from other dementias. Two ELISA assays, the INNOTEST® hTAU Ag and the INNOTEST® PHOSPHO-TAU(181P) for quantification of t-tau and p-tau181 respectively, have been validated to regulatory standards. Validation parameters were determined by repeated testing of human CSF pools. Specimens from Phase 2 studies of the γ-secretase inhibitor semagacestat and the therapeutic antibody solanezumab at baseline and following 12-14 weeks of treatment were also tested. Estimated intra-assay CV for repeated testing of 3 CSF pools were ≤11.5% and RE varied between -14.1% and +6.4%. Inter-assay CV for t-tau was <5% and RE was within ±8%. For p-tau181, inter-assay CV was <9% and RE was within ±2.5%. Total CV (intra-assay plus inter-assay) were below 10% for both analytes. Up to 20-fold dilutional linearity was demonstrated for both analytes. Stability of t-tau and p-tau181 was demonstrated in CSF during five freeze-thaw cycles at ≤-20 °C and ≤-70 °C and at 18-22 °C for up to 24 h. Neither semagacestat nor solanezumab interfered with either assay. Inter-individual t-tau and p-tau181 concentrations were highly variable but intra-individual variations were small. These assays are suitable for analysis of CSF t-tau and p-tau181 in a single laboratory supporting multi-center AD clinical trials. No effect of treatment with semagacestat or solanezumab was observed in response to three months of drug administration.
authors.affiliation: Eli Lilly and Company, Windlesham, UK. drlachno@lilly.com
authors.forename: D Richard
authors.initials: DR
authors.lastname: Lachno
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Romeo
authors.forename: Eric R
authors.initials: ER
authors.lastname: Siemers
authors.forename: Hugo
authors.initials: H
authors.lastname: Vanderstichele
authors.forename: Els
authors.initials: E
authors.lastname: Coart
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Konrad
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Zajac
authors.forename: Jayne A
authors.initials: JA
authors.lastname: Talbot
authors.forename: Hans F
authors.initials: HF
authors.lastname: Jensen
authors.forename: Gopalan
authors.initials: G
authors.lastname: Sethuraman
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Demattos
authors.forename: Patrick C
authors.initials: PC
authors.lastname: May
authors.forename: Robert A
authors.initials: RA
authors.lastname: Dean
mesh_terms: D000368:Aged; D000409:Alanine / Q000031:analogs & derivatives / Q000627:therapeutic use; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid*; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors; D000911:Antibodies, Monoclonal / Q000737:chemistry; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use; D001381:Azepines / Q000627:therapeutic use; D002138:Calibration; D017322:Clinical Trials, Phase II as Topic / Q000379:methods; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D010766:Phosphorylation; D011480:Protease Inhibitors / Q000627:therapeutic use; D015203:Reproducibility of Results; D013048:Specimen Handling; D016875:tau Proteins / Q000134:cerebrospinal fluid*
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D001381:Azepines; C484278:N2-((2S)-2-(3,5-difluorophenyl)-2-hydroxyethanoyl)-N1-((7S)-5-methyl-6-oxo-6,7-dihydro-5H-dibenzo(b,d)azepin-7-yl)-L-alaninamide; D011480:Protease Inhibitors; D016875:tau Proteins; C550616:solanezumab; D053829:Amyloid Precursor Protein Secretases; D000409:Alanine