Aim: Assessment of pre-existing anti-drug antibody (preADA) reactivity at early drug development stages can be beneficial for candidate selection. We investigated the applicability of a generic immune-complex anti-drug antibody (ADA) assay for early preADA assessment as an easily available alternative to the commonly used ADA bridging assay. Results: The results confirmed the expected assay difference regarding isotype detectability. Tested drug candidates were identified as preADA-reactive using the immune-complex ADA assay despite its limitation of not being able to detect IgM-type preADAs. Conclusion: We recommend a purpose-driven use of the two assay formats. For the purpose of ranking different Pro329Gly mutation-bearing drug candidates, the immune-complex ADA assay is preferred in the phase before selecting a drug for clinical development.
Keywords: ADA bridging assay; human autoantibodies; immune-complex ADA assay; immunogenicity; pre-existing anti-drug antibodies; preADA.