Structural Characterization of Antibody Drug Conjugates as Formulated and Under Multiple Conjugation Paradigms

Abstract

Antibody Drug Conjugates (ADCs) combine the specificity of a monoclonal antibody (mAb) with the cytotoxicity of small molecule therapeutics. Biophysical characterization, including the analysis of the conformation and higher-order structure (HOS) of the mAb before and after drug conjugation, is a critical aspect to understanding the stability and eventual efficacy of the ADC. In this study, Trastuzumab-based ADCs are studied using MMS, a novel infrared-based biophysical technique. ADCs produced by two different conjugation methods are structurally compared using the MMS data. Results reveal significant structural discrepancies from the different conjugation methods. These structural differences ultimately contribute to a change in thermal stability of the ADCs measured by Differential Scanning Calorimetry (DSC).