Cell line and protein engineering tools for production and characterization of biologics

Abstract: Our increasing understanding of disease mechanisms coupled with technological advances has facilitated the generation of pharmaceutical proteins, which are able to address yet unmet medical needs. Diseases that were fatal in the past can now be treated with novel biological medications improving and prolonging life for many patients. Pharmaceutical protein production is, however, a complex undertaking, which is by no means problem-free. The demand for more complex proteins and the realization of the importance of post-translational modifications have led to an increasing use of mammalian cells for protein expression. Despite improvements in design and production, the costs required for the development of pharmaceutical proteins still are far greater than those for conventional, small molecule drugs. To render such treatments affordable for healthcare suppliers and assist in the implementation of precision medicine, further progress is needed. In five papers this thesis describes strategies and methods that can help to advance the development and manufacturing of pharmaceutical proteins. Two platforms for antibody engineering have been developed and evaluated, one of which allows for efficient screening of antibody libraries whilst the second enables the straightforward generation of bispecific antibodies. Moreover, a method for epitope mapping has been devised and applied to map the therapeutic antibody eculizumab’s epitope on its target protein. In a second step it was shown how this epitope information can be used to stratify patients and, thus, contribute to the realization of precision medicine. The fourth project focuses on the cell line development process during pharmaceutical protein production. A platform is described combining split-GFP and fluorescence-activated droplet sorting, which allows for the efficient selection of highly secreting cells from a heterogeneous cell pool. In an accompanying study, the split-GFP probe was improved to enable shorter assay times and increased sensitivity, desirable characteristics for high-throughput screening of cell pools. In summary, this thesis provides tools to improve design, development and production of future pharmaceutical proteins and as a result, it makes a contribution to the goal of implementing precision medicine through the generation of more cost-effective biopharmaceuticals for well-characterized patient groups.