An Underlying Cause and Solution to the Poor Size Exclusion Chromatography Performance of Antibody–Drug Conjugates

Antibody-drug conjugate (ADC) size variants are frequently assessed by size exclusion chromatography (SEC). However, poor chromatography performance is often observed during SEC analysis. Existing studies have primarily focused on qualitatively describing non-specific interactions between ADCs and the column matrix. The purposes of the current study are to introduce an underlying cause from a novel perspective on the protein-protein interaction (PPI) mechanism, characterized by quantifying diffusion interaction parameter (k_D) values, and to provide several strategies to reduce PPI and improve column performance during SEC analysis.

Two kinds of ADCs with varying hydrophobicity properties and their corresponding monoclonal antibodies are used as models. The hydrophobicity of these products was verified using the relative calculated logarithm of the partition coefficient of a substance in n-octanol (oil) and water (rCLogP) and reversed-phase high performance liquid chromatography (RP-HPLC), and the size variants were analyzed using SEC. Finally, the PPI was characterized by k_D values of these four products.

The results of rCLogP and RP-HPLC indicated that ADC-1 is relatively hydrophobic, whereas ADC-2 is relatively hydrophilic. In the SEC analysis of the ADC-1, substituting sodium chloride with L-arginine hydrochloride or adding a specific concentration of acetonitrile as an organic solvent to the mobile phase resulted in reduced PPI and enhanced column performance. Conversely, the impact on ADC-2 was negligible.

This study provides insights into improving the performance of SEC analysis for ADCs through strategies involving alterations in mobile phase composition. The changes in column performance can be quantitatively explained by the PPI mechanism.