Comparison of Assay Formats for Drug-Tolerant Immunogenicity Testing

BACKGROUND: Immunogenicity testing is required for safety assessment of biotherapeutic drugs. Because levels observed during biotherapeutic administration can approach the mg/ml range, establishing drug tolerance is significantly important for assay development. RESULTS: Three assay formats for immunogenicity assessment were tested with respect to drug tolerance: Meso Scale Discovery(®) bridging (MSDB), solid-phase extraction with acid dissociation (SPEAD) and affinity capture elution (ACE). Six biotherapeutic drugs were analyzed by the three methods; four monoclonal antibodies, one Fc fusion protein and one Pegylated protein. Overall, ACE performed best for assays involving therapeutic monoclonal antibodies and also functioned well for therapeutic proteins. Despite several advantages, the MSDB assays displayed a potentially significant hook effect. SPEAD was comparable in performance to ACE for the biotherapeutic drugs tested, but suffers the disadvantage of being reagent-intensive. CONCLUSIONS: Novel assay formats offer significant advantages for immunogenicity testing, particularly in the design of assays that are tolerant to circulating levels of the biotherapeutic drug.