Selexis CHO Cells in Suspension-1

Technology FAQs

Selexis enables biopharmaceutical companies to produce virtually any recombinant therapeutic protein, because we have the ability to understand and modify our cells to address productivity and expression challenges.

Technology FAQs

  • Does the vector contain an amplification cassette, such as DHFR or the GS system?

    No. The Selexis SUREtechnology Platform™ does not require gene amplification methods, such as MTX/DHFR/MTX and GS/MSX.

  • Can the libraries be licensed for use in house?

    The SURE CHO-Mplus Libraries™ are only available for the generation of RCBs at Selexis’s headquarters in Geneva.

  • What is the method for transfection?


  • Are there cell line stability issues when all auxiliary proteins and genes of interest are incorporated into the cell’s chromosomal DNA?

    No. We have not experienced any compromise in the stability of the expression of a transgene in our RCBs with the use of Selexis SURE CHO-Mplus Libraries™. We have evaluated this issue for over 60 generations. In fact, the presence of Selexis Genetic Elements™ provides the necessary stability at the locus of integration. Similarly, we have demonstrated the stability of the expression of auxiliary proteins throughout the cell line development.

  • Does the expression of a chaperone or other protein create a problem for FDA approval?

    No, it is believed that the expression of chaperones and other proteins from different pathways does not create a problem for FDA approval. These proteins are CHO proteins—naturally expressed by CHO cells but at very low levels, as shown by transcriptomic analysis. In any case, Selexis can fully characterize any research cell bank (RCB) using the Selexis SUREscan® platform, which combines unique bioinformatics with next-generation sequencing (NGS) and demonstrates the location of any given gene.

  • Can the libraries be modified depending on need?

    Yes, libraries can be constructed “à façon” at Selexis. Selexis can analyze any pathway, based on the transcriptome, and build new libraries. The Selexis team can thus evaluate your project to determine how to best apply and adjust them.

  • Can the libraries be used in our company’s cell lines?

    These libraries were designed based on the genomic and transcriptomic analysis of the Selexis SURE CHO-M Cell Line™ and can therefore only be used with this specific line. It is, however, possible to adapt Selexis’s approach to any other cell line by analyzing transcriptomics data of any given mammalian cell line.

  • Does Selexis have experience generating biosimilars?

    Yes. Selexis has successfully worked on numerous biosimilar programs. Several SUREtechnology Platform™-generated RCBs that express biosimilars are in clinical development, and one biosmiliar Mab drug that has been produced with Selexis technologies has been commercially launched. You can read about a case study on a Selexis-generated biosimilar RCB at [].

  • Where are your RCBs manufactured?

    All RCBs are generated per the highest industry standards at Selexis’s headquarters in Geneva, Switzerland.

  • Do you have experience with difficult-to-express proteins?

    Yes. Since our founding in 2001, we have been leading experts in the know-how and innovative technologies for difficult-to-express proteins. Selexis SUREvectors™ bearing Selexis SGE® remain one of the most effective DNA expression vector systems in the field for expressing DTE proteins. By combining the power of its DNA expression vectors with SURE CHO-Mplus Libraries™, Selexis is in a position to express almost any recombinant protein.

  • After the contract is signed, what is the typical wait time to get a project into the company’s production queue?

    Once contractual negotiations are completed, there is no delay—the project starts immediately.

  • Does Selexis have a preferred CMO?

    Selexis does not have a preferred CMO. Selexis-generated RCBs have been successfully scaled up in CMOs worldwide. However, Selexis can work with you to help determine the best choice for your particular project.

  • Does the company have the ability to conduct genomic characterization in support of generating RCBs?

    Yes. Selexis has the most comprehensive genomic characterization platforms in the industry. Selexis SUREscan® technology is based on Selexis’s proprietary bioinformatics tools, which were co-developed with the Swiss Bioinformatics Institute ( This technology allows for the rapid assembly of DNA sequences from next-generation sequencing (NGS) data from Illumina or PacBio technologies. Selexis SUREscan® maps transgene integration sites, determines the integrity of the integrated transgene sequence, and is used to validate the clonality of an RCB. SUREscan® can also be used to mitigate the potential manufacturing risks associated with adventitious agent contaminants, as it can identify viral sequences from NGS. Selexis is able to perform such analyses on any mammalian cells, including CHO-K1, SP2/0, HEK-293, and PER.C6 cells.

  • Does the company also have the capability and know-how to use non-CHO host cell lines for the production of recombinant proteins?

    Yes. Selexis has successfully generated high-producing cell lines in HEK-293 and NS0 cells.

  • Does Selexis have CHO host cell lines that have been adapted or modified to address secretion issues (eg, misfolding) or perform directed post-translational modifications (eg, carbohydrate modifications) available?

    Yes. The SURE CHO-Mplus Libraries™ were designed to address such complex issues. These libraries, based on the SURE CHO-M Transcriptome™ and genome analysis, can help in generating products with various post-translational characteristics and attributes, including glycan modifications. Furthermore, the SURE CHO-Mplus Libraries™ enable complex proteins (such as multimeric proteins and bispecific mAbs) and difficult-to-express (DTE) proteins (such as fusion proteins) to be folded and secreted in the SURE CHO-M Cell Line™ (Selexis’s CHO K1 derivative cell line).

  • What is the estimated time that is necessary to achieve a high-producing and stable research cell bank (RCB) to support Phase I clinical development?

    − From transfection to RCB: 14 weeks before tech transfer to a CMO of choice.
    − Stability studies: 1 month (4 weeks) for 30 generations or 2 months (8 weeks) for 60 generations. Can be run in parallel with the CMO transfer.
    − Tech transfer to CMO of choice: < 1 week. Molecular Biology Activities:
    − 2-3 weeks for gene synthesis of codon-optimized sequences
    − 2-3 weeks for vector construction


    Cell Culture Activities:
    − From transfection to RCB: 14 weeks before tech transfer to a CMO of choice.
    − Stability studies: 1 month (4 weeks) for 30 generations or 2 months (8 weeks) for 60 generations. Can be run in parallel with the CMO transfer.


    Tech Transfer:
    − Tech transfer and shipping arrangements are conducted in parallel to the cell line development activities (no extra time necessary).
    Material transfer to CMO of choice: < 1 week.

  • What is the typical (gram per liter, g/L) cell line productivity for the following molecules using the SUREtechnology Platform™ in serum-free or chemically defined media?

    As of 2Q 2016:
    – MAb: 2.0–> 5 g/L
    – Fusion Protein: 0.3–0.5 g/L with very low aggregate content
    – Bispecific: 1.0–3.0 g/L with > 90% purity of the bispecific species
    – Fab from – > 2 g/L

  • Do you have agreements in place with the media and feed suppliers that could potentially lower the cost of goods?

    No, but the feed and media that are required by the SUREtechnology Platform™ are not specialty items and are cost-effective.

  • Does the SUREtechnology Platform™ use serum-free or chemically defined media and feed from commercial suppliers in large quantities?

    The Selexis CHO-K1 Cell Line™ (CHO-M) has been optimized for chemically defined (CD), animal-compnent-free, off-the-shelf media, as well as CD feeds that are commercially available from multiple suppliers.

    How many SUREtechnology Platform™-generated RCBs have been used for clinical or commercial manufacturing?


    As of 2Q 2016, over 70 RCBs that have been generated with the SUREtechnology Platform™ are now entering clinical development by Selexis clients, and one product (a monoclonal antibody) has reached the market. Selexis is a leader among RCB-manufacturing companies worldwide, based on the number of RCBs in clinical and commercial manufacturing [Cell Line Development Market Analysis, Market Size, Application Analysis, Regional Outlook, Competitive Strategies and Forecasts, 2015 To 2022. Grand View Research].

  • How is the Selexis SUREtechnology Platform™ different from other available technologies for generating high-expressing and stable mammalian research cell banks (RCBs)?

    There are several patented and proprietary technologies that are unique to the Selexis SUREtechnology Platform™. Embedded in our transfection vectors, Selexis SGE® (Selexis Genetic Elements) are patented chromatin modifiers that unwind the DNA at the site of transgene integration, boost transcription, and thus increase recombinant protein expression. Selexis has optimized the DNA sequence of its human SGEs that are integrated into the DNA expression vector to obtain the highest and most reproducible gene expression levels across all recombinant protein types.


    Even with high transcription levels, high-level protein expression can be thwarted by translation and secretion bottlenecks. To address such issues, Selexis has sequenced the transcriptome of its CHO K1 cell line to obtain the expression levels of its CHO proteins. Selexis then developed the SURE CHO-Mplus Libraries™ to repair and improve the pathways that are impaired in its CHO K1 cells. This unique and sophisticated platform is designed to rapidly and simultaneously address several translation and secretion bottlenecks that can occur with difficult-to-express proteins, such as blood coagulation factors, bispecific monoclonal antibodies, and Fc fusion proteins. With the SURE CHO-Mplus Libraries, Selexis has helped clients rescue promising candidates that have now entered clinical trials.


    Selexis announced the launch of the Selexis SUREscan® platform, which uses unique bioinformatics combined with next-generation sequencing (NGS) to fully characterize research cell banks (RCBs). By analyzing whole genomes, Selexis has no bias in characterizing and documenting RCBs and thus can provide the complete map of any genome in a mammalian cell. Selexis SUREscan® maps transgene integration sites, determines the integrity of the integrated transgene sequence, is used to validate the clonality of an RCB, and, finally, is used to mitigate potential manufacturing risks that are associated with contamination by adventitious agents.