How to achieve high-yielding cell lines

30th May 2017

Category: Cell Line Development

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By: Dr Christoph Zehe, Head of Technology Development

The global market for biological products is expected to reach $287bn by the end of 2020. There are many drivers for the continued investment and development of therapeutic protein products, such as: an increase in incidences of cancer and autoimmune diseases, reduction in side effects, advances in technology and patent expiry of blockbuster drugs.

Although the market is growing, the cost of developing a biologic drug remains high, due to the complex process development and manufacturing requirements of biologic drugs.

A key factor in reducing the production costs of biologic drugs is to develop a cell line that produces a high-yield of product.

Evaluation of signal peptides (SP) for enhanced protein expression

The high-titer production of biologic drugs using “Chinese hamster ovary” (CHO) cells is an important pillar of the biopharmaceutical industry. A potential bottleneck for profitable production is the successful secretion of the synthesized proteins through the endoplasmatic reticulum (ER) and the Golgi apparatus into the culture medium. The transport into the ER is directed by the signal peptide (SP), a protein sequence at the N-terminus of the product. (Figure 1). Since natural SP sequences and efficiencies vary between proteins and species, the utilization of different SPs can lead to enhanced protein expression in existing production systems.

Signal Peptide in CHO DG44 CellsFigure 1: Signal peptide recognition and translocation of the protein into the endoplasmatic reticulum (ER) in the secretory pathway of mammalian cells.

Achieving high-yielding CHO cell lines

In a recent development study, Sartorius Stedim Cellca e compared the influence of four different natural SPs on the secreted amount of an IgG4 model antibody using a CHO DG44 host cell line. Employing different pool generation strategies, the best producing pools obtained with each SP and the standard SP were analyzed regarding their fed-batch performance. SP(9) was identified as a promising candidate and was subsequently investigated in a second approach to analyze the influence of this SP on the secretion of four additional antibody products. For this purpose, large and mini pools were generated expressing the respective product with the standard signal peptide as well as with SP(9).Fed-batch experiments were performed for final evaluations.

For the first approach, the results revealed a 2.4-fold increase in average final fed-batch antibody titer of SP(9) when compared to the standard SP approach (standard SP = 0.44 g/L; SP(9) = 1.50 g/L).

In the second approach, an improved performance was observed for all products when comparing SP(9) and the standard SP with an increase in average final fed-batch titers ranging from 27 to 353%. Taken together, with a positive influence on the final concentrations of all products the results contribute to the optimization of the Sartorius Stedim Cellca standard cell line development process. Achieving high-yielding cell lines is a challenging process in the development of biologic drugs. The Cellca CHO Expression Platform has been specifically designed to deliver titers upwards of 3g/l to help biopharmaceutical companies to reduce production costs.

Download our scientific poster, recently presented at ESACT 2017 Conference, for more information and to view the data from this experiment.

 

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