Application of an electrochemiluminescence assay for quantification of E6011, an antifractalkine monoclonal antibody, to pharmacokinetic studies in monkeys and humans

Abstract

Background: E6011, a humanized antifractalkine monoclonal antibody, is under development for the treatment of various inflammatory diseases, such as rheumatoid arthritis. A reproducible assay method has been developed for the determination of E6011 in monkey and human serum by electrochemiluminescence (ECL) assay. Methods: E6011 in serum was captured by fractalkine and detected by ruthenium-labeled rabbit anti-E6011 Fab polyclonal antibodies for ECL detection. E6011 in serum was quantifiable from 0.02 and 0.1 μg/mL in monkey and human serum, respectively, with minimum required dilution of 500. The method was then validated in accordance with bioanalytical guidelines. Results: Accuracy and precision of quality control samples at five concentrations in intra- and interbatch reproducibility demonstrated that relative error and relative standard deviation were within acceptable criteria. Recovery of E6011 was 92.9%-121.7% and 85.0%-109.3% in humans and monkeys. Dilution integrity, no prozone effects, and no impacts by antigen were also ensured. Parallelism was also confirmed using incurred clinical sample analysis. Various types of stability were assessed, which confirmed that E6011 in serum was stable for 367 and 735 days in monkey and human sera, respectively, under frozen conditions. Conclusion: The developed method was successfully applied supporting pharmacokinetic studies in monkeys and humans.