Impact of positive control binding properties on anti-drug antibody assay performance.

Background: Monitoring anti-drug antibodies (ADAs) is a critical component of recombinant protein drug development. Positive controls in ADA assays are essential for evaluating assay quality, yet the influence of their binding properties on assay performance is not well understood.

Research design and methods: We evaluated a panel of surrogate positive controls with varying binding characteristics to investigate how their affinity and kinetic parameters impact ADA assay performance. Binding properties were measured using Bio-Layer Interferometry (BLI), and assays were evaluated for relative sensitivity and drug tolerance. This was a laboratory-based study; no human or animal subjects were involved.

Results: We observed a correlation between higher affinity (lower K_D (equilibrium dissociation constant)) and lower k_off (off-rate constant) with increased relative assay sensitivity. However, no consistent relationship was found between these binding parameters and drug tolerance. These findings suggest that binding kinetics of the positive control can significantly influence sensitivity but may not predict drug tolerance.

Conclusions: Understanding the relationship between positive control binding properties and ADA assay performance can support the selection of reagents that optimize sensitivity. Limitations include the use of surrogate positive controls, which may not fully replicate the complexity of clinical ADA responses.