Fit-for-purpose validation of a drug-tolerant immunogenicity assay for a human mAb drug in animal safety studies

Abstract

A modified biotin-drug extraction and acid dissociation (BEAD) immunogenicity assay was developed to detect anti-drug-antibodies (ADA) against the human anti-FXIIa monoclonal antibody (mAb) drug, Garadacimab (previously called CSL312). Multiple strategies were tested to optimize the signal-to-background (S/B) ratio, assay sensitivity and the drug tolerance. The modified BEAD assay was found to be highly drug tolerant (>500 μg/ml) with a sensitivity of 100 ng/ml, in line with current FDA regulatory guidelines. The assay was validated for use in a repeat-dose animal safety study and showed an acceptable intra-assay precision and robustness but a lower inter-assay precision. In-study sample analysis confirmed that the assay was fit-for-purpose (FFP) for the context-of-use (COU) in the nonclinical study and the results obtained were deemed meaningful.