Elution Profiles of Antibody-Drug Conjugates in Preparative Chromatography

Abstract

Monoclonal antibody drug conjugate (ADCs) have received much attention as pharmaceutical agents for treating serious diseases such as cancer. However, it is difficult to separate them on the basis of the drug to antibody ratio, DAR. Hydrophobic chromatography (HIC) is commonly used for the analysis of the drug to antibody ratio, DAR. The retention of ADCs on HIC can be controlled by the hydrophobic nature of ADCs, depending on the mobile phase conditions. They are sometimes performed at the restricted conditions where the solubility is too low. Ion exchange chromatography (IEC) using electrostatic interaction is an orthogonal method to HIC. IEC is widely used because of its higher capacity than HIC. We investigated the retention behavior of the protein conjugated with surrogate drugs on IEC. The surrogate drugs employed are 7-diethylamino-3-(4’-maleimidylhenyl) 4-methylcoumarin (CPM), N-(1-pyrenyl) maleimide (NPM). Bovine serum albumin (BSA) was used as a model protein. The molar ratio (CPM and NPM to protein) was set to 3. The maleimide group of CPM and NPM reacts with the thiol group of the proteins. On the linear gradient elution experiments, the elution salt concentrations of the conjugated and non-conjugated proteins were measured to obtain chromatographic parameter of the number of binding sites, B.