Measuring biotherapeutics with endogenous counterparts and pre-existing antibodies: an interferon case study

Background: This article presents case study data demonstrating the importance of having a thorough understanding of matrix-interference in support of global clinical trials. Methods/Results: A ligand-binding assay used in the measurement of interferon lambda in human serum was transferred from the reference laboratory to a US-based comparator laboratory and then to a China-based comparator laboratory. The method was successfully validated at each laboratory, however, during cross-validation, there were notable differences, including 30–60% difference in incurred study sample results. The differences were attributed to matrix factors included in the serum pool used to prepare standards and quality controls. Newly procured serum (n = 75 individuals) was tested for assay interference. 12% contained either pre-existing antibodies (auto-antibodies) or were identified as pharmacokinetic assay outliers. Conclusion: Prescreening of serum to exclude reactive individuals resulted in successful cross-validation and...