A homogeneous time-resolved fluorometric energy transfer assay for the binding assessment of FcRn with IgG antibodies

We aimed to develop a homogeneous time-resolved fluorometric energy transfer assay for assessment of human neonatal Fc receptor binding activity with IgG-type antibodies. The assay was configured with FcRn-coupled with Eu cryptate via biotin and streptavidin interaction as donor and IgG1 labeled with d2 as acceptor. Only a single incubation step was involved and no wash step was required. The assay demonstrated good accuracy, precision, linearity and specificity. Our further investigation with a rat pharmacokinetics study revealed that the terminal t1/2 for Trastuzumab and its related three ADCs agreed with the EC50 data. The assay can be applied to various IgGs with modifications to identify antibodies with appropriate binding ability to human FcRn.

Automated summary

The study developed a homogeneous time-resolved fluorometric energy transfer assay for assessing human neonatal Fc receptor binding activity with IgG antibodies. The assay showed good accuracy, precision, linearity, and specificity, and was further validated in a rat pharmacokinetics study. This assay has the potential for identifying antibodies with appropriate binding ability to human Fc receptors through modifications.