Objective

The manufacture of antibody-drug conjugates (ADC) is a complex multi-step process where the antibody is modified post-purification to impart additional functionality, stability and/or efficacy. Product quality and functionality must be monitored at various check-points during the process; particularly during the method development and scale-up manufacture of ADC where the reaction conditions for conjugation may be “non-physiological” and damaging to the product. In this case, it is desirable to monitor the binding of the antibody to its target during the method development phase and subsequently during scale-up manufacture. Normally, cell-death assays are used to test the efficacy of the final product but this method is low throughput, slow, unreliable and too expensive to be used routinely for screening large numbers from a Design of Experiment (DOE) development programme. Therefore, there is a need for tools that allow the rapid development of assay methods to screen ADCs during their development through to large scale manufacture. Here we report preliminary data on the development of an assay for the binding of trastuzumab to its target peptide on Her2 protein. A proprietary OrlaSURF approach was used to fuse a Domain IV epitope from human Her2 protein to an anchoring domain that allows the presentation of the peptide on ELISA plates and biosensor chips with its structure intact and in the correct orientation for maximum accessibility of trastuzumab. The trastuzumab-Her2 binding assay was developed and shown to be sensitive with a LoD of <10 ng/mL trastuzumab and highly reproducible and reliable. The assay was used to test the effect of toxin conjugation on trastuzumab-Her2 interaction and a correlation of binding ability with cell-kill ability was demonstrated. This method provides a rapid, reliable, scalable, high-throughput method for process development of ADC manufacture and will be applicable to any ADC development.