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
Affiliations: [a] Eli Lilly and Company, Windlesham, UK | [b] Covance Central Laboratory Services, Inc., Indianapolis, IN, USA | [c] Innogenetics NV, Gent, Belgium | [d] Lilly Research Laboratories, Indianapolis, IN, USA | [e] Lilly-NUS Centre for Clinical Pharmacology Pte Ltd, Singapore
Correspondence:
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Correspondence to: Dr. D.R. Lachno, Eli Lilly and Company, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, UK. Tel.: +44 1276 483508; Fax: +44 1276 483416; E-mail: drlachno@lilly.com.
Note: [1] Present: Biomarkable, Gent, Belgium.
Abstract: 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.
