Validation of a multiplex assay for simultaneous quantification of amyloid-β peptide species in human plasma with utility for measurements in studies of Alzheimer's disease therapeutics

• Published in: Journal of Alzheimer's disease Vol. 32; no. 4; p. 905
• Main Authors: Lachno, D Richard, Emerson, Julie K, Vanderstichele, Hugo, Gonzales, Celedon, Martényi, Ferenc, Konrad, Robert J, Talbot, Jayne A, Lowe, Stephen L, Oefinger, Paul E, Dean, Robert A
• Format: Journal Article
• Language: English
• Published: Netherlands 01.01.2012
• Subjects: Alzheimer Disease - blood; Alzheimer Disease - drug therapy; Amyloid beta-Peptides - blood; Fluorescence Polarization Immunoassay - methods; Fluorescence Polarization Immunoassay - standards; Humans; Peptide Fragments - blood; Plasma - chemistry; Pyrimidines - blood; Pyrimidines - therapeutic use; Thiazines - blood; Thiazines - therapeutic use
• ISSN: 1875-8908
• DOI: 10.3233/JAD-2012-121075

The aim of this study was to validate the INNO-BIA plasma amyloid-β (Aβ) forms assay for quantification of Aβ1-40 and Aβ1-42 according to regulatory guidance for bioanalysis and demonstrate its fitness for clinical trial applications. Validation parameters were evaluated by repeated testing of human EDTA-plasma pools. In 6 separate estimates, intra-assay coefficients of variation (CV) for repeated testing of 5 plasma pools were ≤9% and relative error (RE) varied between -35% and +22%. Inter-assay CV (n = 36) ranged from 5% to 17% and RE varied from -17% to +8%. Dilutional linearity was not demonstrated for either analyte using diluent buffer, but dilution with immuno-depleted plasma by 1.67-fold gave results within 20% of target. Analyte stability was demonstrated in plasma at 2-8 °C for up to 6 h. Stability during frozen storage up to 12 months and through 3 freeze-thaw cycles at ≤ -70 °C was also demonstrated in 5 of 6 individuals but deteriorated thereafter. Neither semagacestat nor LY2811376 interfered with the assay but solanezumab at 500 mg/L reduced recovery of Aβ1-42 by 53%. Specimens from a Phase I human volunteer study of the β-secretase inhibitor LY2811376 were tested at baseline and at intervals up to 12 h after single oral doses, demonstrating a clear treatment effect. During 1,041 clinical assay runs from semagacestat studies over 10 months, the CV for plasma quality control pools at three levels were ≤15% and RE were <10%. In conclusion, the INNO-BIA plasma assay was successfully validated and qualified for use in clinical research.