LC–MS Challenges in Characterizing and Quantifying Monoclonal Antibodies (mAb) and Antibody-Drug Conjugates (ADC) in Biological Samples

Abstract

Monoclonal antibody (mAb) represents majority of protein therapeutics with more than 50 antibodies and 3 antibody-drug conjugates (ADCs) on the market to treat cancers and other diseases. Liquid chromatography mass spectrometry (LC–MS) provides a common tool and has been routinely used to characterize and quantify mAb and ADCs and their catabolites in discovery as well as development of antibody-related therapeutics. The major challenges for LC–MS-based analysis of mAb include limited sensitivity and lack of understanding of the nature of biotransformation and its impact on quantitation data. The analytical challenges associated with ADCs are around characterizing and quantifying the dynamically changing mixture of ADC species in circulation due to catabolism of the antibody, linker, or payload. Tissue collection and analysis, although is practically limited in the clinical research, offers direct assessment of the responsible molecular species at the site of action for the efficacy and toxicity. This review attempts to discuss LC–MS-based analytical challenges and opportunities in discovery and development of mAb and ADC therapeutics. Potential applications of the LC–MS analytical data in relation to the efficacy and toxicity of these molecular entities are also discussed here.