Antibody-Drug Conjugate Mimic Purification with TOYOPEARL® PPG-600M HIC RESIN for DAR-Separation

Introduction

Antibody-drug conjugates (ADCs) are promising anti- cancer biopharmaceuticals with one of the highest annual growth rates. Four ADCs received market approval to this point. They combine the high selectivity and affinity of an antibody to cancer cells with the toxicity of chemothera- peutics in one molecule.

ADCs consist of a monoclonal antibody, covalently bound via a linker to a highly potent cytotoxic drug. Due to the highly toxic payload, very high safety standards should be implemented during method and process development. ADC-mimic contain a non-toxic payload with similar struc- ture and physicochemical properties as the toxic payload of an ADC. Therefore, they can be used as a model to develop a suitable purification process or analytical method. The ADC-mimic in this work consists of Adalimumab bound to Fluorescein 5-isocyanate (FITC).

The purification process of ADCs is complex due to the heterogeneity of the conjugates. The main challenges are in the isolation of the unconjugated antibody and free drug, and the separation in different Drug-Antibody-Ratio (DAR), which correlates with the potency of the ADC. High DARs are associated with high cytotoxic levels and can cause aggregation, affecting the stability of the ADC. On the other hand, low DARs affect the efficacy of the therapeutics.

The mass spectrometric evaluation shows, that the ADC-mimic developed at Tosoh Bioscience displays a similar drug-to-antibody ratio as real ADCs. Thus, this ADC-mimic is a useful tool for analytical and preparative method development.