posted on 2022-02-01, 10:04authored byTyler K. Davis, Mark E. Jennings
Drug-load
(DL) characterization of antibody–drug conjugates
(ADCs) is an important analytical task due to its designation as a
critical quality attribute (CQA) affecting potency and stability.
Intact and subunit liquid chromatography–mass spectrometry
(LC–MS) analyses can determine global drug-to-antibody ratios
(DARs) that correlate well with other orthogonal analytical methods;
however, peptide mapping liquid chromatography–tandem mass
spectrometry (LC–MS/MS) analysis has struggled to provide complementary
site-specific quantitation of drug conjugation sites. The peptide
mapping method described herein utilizes stable isotope labeling to
accurately quantitate the site-specific conjugation levels of a cysteine-conjugated
ADC to provide “bottom-up” DAR characterization in parallel
with protein sequence and post-translational modification (PTM) characterization
in one multi-attribute analytical method (MAM).