Mitigating target interference challenges in bridging immunogenicity assay to detect anti-tocilizumab antibodies.

An assay to detect anti-tocilizumab antibodies in the presence of high levels of circulating target and drug is needed for immunogenicity assessment in comparative clinical studies. An assay was developed and validated using a combination of blocking agents and dilutions to overcome target interference challenges. No false-positive signal was detected in serum samples spiked with 350-500 ng/ml of IL-6 receptor.