The most common approach to understand macromolecule biotransformation is to use a surrogate analyte method and measure fragments from the region of interest to indirectly confirm the structural integrity of the macromolecule . This was performed with LC-MRM methods for all ADCs in this study. The LBA-LC-MRM method was used to generate absolute quantitative results for the total Ab, intact Ab and ADC assay (Figure , Table ). The data generated using the three methods resulted in overlapping concentration-time profiles for all four ADCs, suggesting that no significant de-conjugation was observed, and the protein scaffold remained stable. The differences in concentration-time profiles between the four ADCs with various linkers were not significant when characterized with LBA-LC-MRM assays, considering the 20% accuracy and precision acceptance criteria for the assays.