Validation of an integrated series of ligand-binding assays for the quantitative determination of antibody–drug conjugates in biological matrices

The bioanalytical strategy for antibody–drug conjugates (ADC) includes multiple integrated measurements of pharmacologically relevant ADC. Methods & results: Three ligand-binding assays were validated for the measurement of total antibody, active ADC and total ADC. Accuracy and precision demonstrate %bias from -8 to 14%, %CV from 3 to 11% and total error from 3 to 21%, with >98% samples meeting incurred sample reanalysis criteria. Each assay met stability, selectivity, dilutional integrity, carry over and specificity criteria with no interference from associated metabolite/impurity. Given the active ADC assay sensitivity to payload, active ADC was used to assess drug to antibody ratio. Discussion...