Development of an In Vitro Potency Assay System for Quality Control of Anti- Human Epidermal Growth Factor Receptor 2 Antibody Admixtures

Although the physical/chemical stability and potential interactions of trastuzumab and pertuzumab in a single infusion bag before co-administration have been evaluated preliminarily, it is not easy to clarify which monoclonal antibodies changes when the admixtures were analyzed as a whole, especially for in vitro potency evaluation. In this study, take admixtures of pertuzumab and trastuzumab biosimilar products as samples, an in vitro potency assay system was developed that can monitor the changes of potency of each monoclonal antibodies as well as their admixtures. Development of the assay system included 3 steps, the first step is to develop protein quantification assay for each monoclonal antibodies by specific antigen based enzyme-linked immunosorbent assay, then a specified cell based potency assay that could be used to measure the biological potency of each monoclonal antibodies and their admixtures was developed. After that, the enzyme-linked immunosorbent assay based protein quantification assay and the specified cell based potency assay were qualified for accuracy and precision. Meanwhile, admixtures containing different amount ratios of pertuzumab and trastuzumab biosimilar products were prepared and measured by the well qualified assays. Finally, the potency test data generated from admixtures of different amount ratio were summarized as an analysis table. The analysis table plus protein quantification results were then used as the basic tool for further in vitro potency evaluation of unknown admixtures. Using this system, the change of potency of each monoclonal antibodies in admixtures could be monitored. The in vitro potency assay system was then qualified in evaluating forced degraded samples. This study represents a good example on thorough biological potency evaluation for monoclonal antibodies admixtures.