Analysis of ADCs by Native Mass Spectrometry

Abstract

Mass spectrometry performed in nondenaturing conditions (native MS) has proven its utility for the quantitative and qualitative analysis of antibody-drug conjugates (ADCs), especially when ADCs’ subunits involve noncovalent interactions (i.e., cysteine-conjugated ADCs). Its hyphenation to ion mobility spectrometry (IM-MS) allows differentiation of gas-phase ions based on their rotationally averaged collision cross section providing an additional dimension of conformational characterization of ADCs. More recently, size exclusion chromatography (SEC) appeared as an interesting technique to perform online buffer exchange in an automated way prior to native MS/IM-MS analysis. Online SEC-native MS/IM-MS allows the global structural characterization of ADCs and the assessment of some critical quality attributes (CQAs) required for ADC release on the market, such as drug load distribution (DLD), drug-to-antibody ratio (DAR), the average DAR (DARav), and the relative amount of unconjugated mAb.