Determination of ADC Concentration by Ligand-Binding Assays

Total antibody, conjugated antibody or antibody-conjugated drug, and free drug are key analytes required to establish exposure-response relationships for ADCs. Therefore, bioanalytical strategies for ADCs include ligand-binding assays (LBA) and LC-MS/MS methods. Here we describe detailed methodology to develop a solid-phase-based enzyme-linked immunosorbent assay (ELISA), which is the most widely used LBA to quantify large-molecule components of ADC in biological matrices such as plasma, serum, tumor, or tissue homogenates. The approach presented here is designed to quantify total antibody concentrations in ADC containing samples, and can be easily adapted to quantify conjugated antibody concentrations.