Site-Specific Quantitation of Drug Conjugations on Antibody–Drug Conjugates (ADCs) Using a Protease-Assisted Drug Deconjugation and Linker-like Labeling (PADDLL) Method

Antibody–drug conjugates (ADCs) are biopharmaceuticals for the targeted delivery of antitumor agents. ADCs can be highly heterogeneous with various drug-to-antibody ratio (DAR) species, conjugation sites, and occupancy levels. The conjugation site can modulate the ADC stability and efficacy and therefore can be considered to be a critical quality attribute (CQA) during development. Traditional mass spectrometry (MS)-based peptide mapping methods...