New analytical challenges in characterization of antibody-drug conjugates

Abstract

Since 1913, when Paul Ehrlich introduced the concept of “selective toxicity”, new strategies to obtain quality control, quantification of the drug were mandatory. For this reason, the introduction of antibody drug conjugates (ADC) has shown many critical points, being these systems made of small- and high-molecular weight compounds. Being ADCs a novelty for showing therapeutic action, they were subjected to a grow up in studies. There are in literature several approaches to follow ADCs for in vivo and in vitro studies because type of conjugation, release of the drug, and body-distribution are characteristic for each of them, resulting in many critical steps.

Liquid chromatography (LC) and capillary electrophoresis (CE) are the most common analytical technique used in order to obtain the aim. For the characterization of ADCs, there are several chromatographic techniques. HPLC finds application in both small and large molecules, related to the availability of various modes of separation (reversed-phase, size exclusion, ion exchange, mixed-mode etc.). Capillary electrophoresis (CE) finds its main application in large molecule therapeutics, where its electrophoretic separation mechanism offers a distinct, and often superior, separation of macromolecules compared to classic chromatographic techniques. Several modes of CE, including capillary electrophoresis sodium dodecyl sulphate (CE-SDS), capillary zone electrophoresis (CZE), and capillary isoelectric focusing (CIEF) or imaged capillary isoelectric focusing (iCIEF) are commonly utilized in characterization of the critical quality attributes (CQAs) of monoclonal antibody drugs such as charge variants, size variants, and positional isomers/purity etc.

In this review, analytical methods for physicochemical characterization of ADCs will be reported and analysed in order to highlight as the chromatographic procedures allow obtaining a complete ADCs evaluation and characterization.