Antibody-drug conjugates (ADCs) are cutting-edge biotherapeutics that selectively target specific cells by linking potent cytotoxic drugs to monoclonal antibodies (mAb). Variations in the number of drug molecules linked to the mAb, via cysteine-based, lysine-based or site-specific, can result in complex charge heterogeneity profiles. Additionally, the type of linker and post-translational modifications, like glycosylation, glycation, or deamidation can also contribute the heterogeneity of the product. This technical note demonstrates a novel integrated workflow using the Intabio ZT system for charge variant analysis of ADCs. Coupling icIEF directly to MS significantly reduces acquisition and analysis time compared to ion exchange chromatography (IEX) with fraction collections, eliminating multiple weeks of effort.
The icIEF-UV/MS data was acquired using an Intabio ZT system and processed within Biologics Explorer software for automated protein deconvolution and accurate DAR calculation. With a single injection, 8 different trastuzumab emtansine (T-DM1( payloads were electrophoretically separated and an average DAR of 3.6 was measured.