title: Validation of assays for measurement of amyloid-β peptides in cerebrospinal fluid and plasma specimens from patients with Alzheimer's disease treated with solanezumab.
abstract: The aim of this study was to validate new assays for measurement of amyloid-β (Aβ) peptides in cerebrospinal fluid (CSF) and plasma specimens in clinical studies of solanezumab according to current regulatory recommendations. Four assays based on the INNOTEST® β-AMYLOID(1-42) and prototype INNOTEST β-AMYLOID(1-40) kits were developed and validated. To render these assays 'solanezumab-tolerant', excess drug was added to calibrators, quality control, and test samples via a 2-fold dilution with kit diluent. Validation parameters were evaluated by repeated testing of human CSF and EDTA-plasma pools containing solanezumab. Calibration curve correlation coefficients for the four assays were ≥0.9985. Intra- and inter-assay coefficients of variation for Aβ1-40 and Aβ1-42 were ≤13 and ≤15%, respectively for both matrices. Dilutional linearity, within and between assays, was demonstrated for both analytes in CSF and plasma at clinically relevant dilution factors. This dilution regimen was successfully applied during Phase 3 clinical sample analysis. Aβ1-40 and Aβ1-42 were stable in CSF and plasma containing solanezumab at 2-8°C and room temperature for up to 8 h and during 5 additional freeze-thaw cycles from ≤-20 and ≤-70°C. Results of parallel tests on stored clinical samples using INNOTEST methods and proprietary ELISA methods were closely correlated (r2 > 0.9), although bias in reported concentrations was observed between assays. In conclusion, the modified INNOTEST assays provided (relatively) accurate and precise quantification of Aβ1-40 and Aβ1-42 in CSF and plasma containing solanezumab according to established consensus validation criteria. The clinical experience with these assays post validation has shown them to be robust and reliable.
authors.affiliation: Eli Lilly and Company, Windlesham, UK. drlachno@lilly.com
authors.forename: D Richard
authors.initials: DR
authors.lastname: Lachno
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Evert
authors.forename: Hugo
authors.initials: H
authors.lastname: Vanderstichele
authors.forename: Michael
authors.initials: M
authors.lastname: Robertson
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Demattos
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Konrad
authors.forename: Jayne A
authors.initials: JA
authors.lastname: Talbot
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Racke
authors.forename: Robert A
authors.initials: RA
authors.lastname: Dean
mesh_terms: D000544:Alzheimer Disease / Q000097:blood / Q000134:cerebrospinal fluid / Q000188:drug therapy; D016229:Amyloid beta-Peptides / Q000097:blood* / Q000134:cerebrospinal fluid* / Q000276:immunology; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D019921:Biotinylation; D002138:Calibration; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D010446:Peptide Fragments / Q000097:blood* / Q000134:cerebrospinal fluid*; D012016:Reference Values; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D016229:Amyloid beta-Peptides; D061067:Antibodies, Monoclonal, Humanized; D014150:Antipsychotic Agents; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); C550616:solanezumab