Statistical and bioanalytical considerations for establishing a depletion criterion for specificity testing during immunogenicity assessment of a biotherapeutic

Elucidation of the statistical factors that influence anti-drug antibody cut point setting through a multi-laboratory study

Aim: Appropriateness of anti-drug antibody (ADA) assay is critical for immunogenicity assessment of biopharmaceuticals. Although cut point setting in ADA assay has a large impact on the results, a standard statistical approach for its setting has not been well established. Methodology: In this multi-laboratory study, to elucidate factors influencing the cut point setting, we compared the statistical approaches and calculated cut points for multiple datasets of ADA assays using the individual procedure employed at each laboratory. Conclusion: We showed that outlier exclusion, false-positive rate and investigating data distribution have the greatest impact on both screening and confirmatory cut points. Our results would be useful for industry researchers and regulators engaged in immunogenicity assessment of biopharmaceuticals.

Recommendations for the development and validation of confirmatory anti-drug antibody assays

Identification and characterization of anti-drug antibodies is a critical component of biopharmaceutical drug development. The tiered approach for immunogenicity testing consists of screening, confirmatory, and characterization assays. Herein, we provide recommendations for confirmatory assays by expanding upon published guidance and present common practices across the industry. The authors recommend scientific approaches for development and validation of confirmatory assays using competition methods in ligand-binding assays, along with statistical formulae for routine use and validation. The paper will assist in understanding the confirmatory assay, and carefully implementing validation criteria a priori, as well as during sample analysis. These approaches represent the authors’ current knowledge and practices, with the aim that more uniform practices will be applied across the industry.