New Frontiers in ADC Analysis: Advances in Chromatography, Electrophoresis, and Mass Spectrometry.

Antibody-drug conjugates (ADCs) are composed of a tumor-targeting mAb conjugated to a cytotoxic payload to enable the selective delivery of the cytotoxic moiety while reducing the side effects and immunogenicity to the patient. Since the first ADC approval by the FDA, the design of new generation of ADC products has been extensively developed to improve the therapeutic efficiency of first-generation ADCs. Concomitantly, different analytical methods have been improved to enable critical quality attributes (CQA) assessment and thus support ADCs development and production at different stages. In this context, liquid chromatography (LC), capillary electrophoresis (CE), and mass spectrometry (MS) have played a predominant role in ADCs characterization, showcasing the advantages of these methods to identify and potentially quantify the different ADCs populations resulting from the bioconjugation process. This review provides a detailed overview about cutting-edge analytical methods with a particular focus on studies reported during the last five years related to LC, CE, and MS, allowing not only a deeper insight into ADCs structure, but also to provide further evidence about their in vitro and in vivo biotransformation products. The maturity, robustness, and high throughput associated to these methods allow their progressive introduction in regulatory and clinical environments, ensuring the structural integrity of ADCs prior to their administration to the patients. The examples reported in this review article clearly highlight the relevance of using tailored analytical strategies for a more comprehensive ADC characterization and thus continue the contribution to early developability assessment and bring next-generation ADCs into the market.