Anti-drug Antibody Sample Testing and Reporting Harmonization.

A clear scientific and operational need exists for harmonized bioanalytical immunogenicity study reporting to facilitate communication of immunogenicity findings and expedient review by industry and health authorities. To address these key bioanalytical reporting gaps and provide a report structure for documenting immunogenicity results, this cross-industry group was formed to establish harmonized recommendations and a develop a submission template to facilitate agency filings. Provided here are recommendations for reporting clinical anti-drug antibody (ADA) assay results using ligand-binding assay technologies. This publication describes the essential bioanalytical report (BAR) elements such as the method, critical reagents and equipment, study samples, results, and data analysis, and provides a template for a suggested structure for the ADA BAR. This publication focuses on the content and presentation of the bioanalytical ADA sample analysis report. The interpretation of immunogenicity data, including the evaluation of the impact of ADA on safety, exposure, and efficacy, is out of scope of this publication.

A bridging immunogenicity assay for anti-cabiralizumab antibodies: overcoming the low assay cut point and drug tolerance challenges.

Background: To support the clinical studies of cabiralizumab, an immunogenicity assay for detecting anti-cabiralizumab antibodies is required. Results: Strategies were developed to overcome two major bioanalytical challenges: poor drug tolerance of the anti-drug antibodies assay and very low cut point observed in the screening and confirmatory assays. By using acid dissociation (400 mM glycine solution at pH 2.0), drug tolerance of 200 µg/ml drug was achieved for both the screening and confirmatory assays. Effects of biological matrix (disease state vs normal serum) and assay conditions (capture/detector reagent concentration, minimum required dilution, acid pretreatment) on assay cut points were systematically evaluated. Conclusion: A bridging immunogenicity assay for detecting anti-cabiralizumab antibodies in human serum has been successfully developed, validated and applied to clinical studies.

Strategies for method comparison when changes in the immunogenicity method are needed within a clinical program.

Aim: To present the reader with different approaches used to compare immunogenicity methods when changes are needed during a clinical program. Results: Five case studies are presented, in the first two case studies, the approach utilized a small sample size for the comparison. In the third case, all samples from a study were analyzed by both methods. In the fourth case, the intended use of noncomparable assays in an integrated summary drove design of experiments to establish the expected limits of pooling data. In the fifth case, a selectivity approach was used as an alternate to use of incurred samples. Conclusion: When data pooling across methods is needed, it is important to define the limits of comparability.

Old to new ligand-binding assay method modifications.

This article aims to address approaches to ensuring method changes for regulated ligand-binding assays of biologics drugs from old to newer formats and technology are properly understood, characterized and validated to meet current industry expectations and regulatory requirements. Sections in the chapter will include descriptions of different formats of ligand-binding assays, reasons that may drive updating of methods and procedures for qualifying method changes for immunoassays that are designed to support PK and immunogenicity analyses for clinical and nonclinical applications. Case studies from the authors' experience, as well as literature references will be provided as examples of challenges, as well as providing guidance of when and how to provide smooth transitions of older methods to newer, more robust or sensitive methods as reagents or technology are available.